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Background: Some evidence-based therapies are underused in patients with a poor prognosis despite the fact that the survival gains would be highest among such patient subgroups. The extent to which this applies for acute, life-saving therapies is unknown. The impact of prognostic characteristics and pre-existing conditions on the use of reperfusion therapy among eligible patients with acute ST segment elevation myocardial infarction is examined., Methods: Of 2829 acute myocardial infarction patients prospectively identified in 53 acute care hospitals across Ontario, 987 presented with ST segment elevation within 12 h of symptom onset and without any absolute contraindications to reperfusion therapy. The baseline prognosis for each patient was derived from a validated risk-adjustment model of 30-day mortality. Multiple logistical regression was used to examine the relationships among reperfusion therapy, prognosis and the number of pre-existing chronic conditions after adjusting for factors such as age, sex, time since symptom onset and socioeconomic status., Results: Of the 987 appropriate candidates, 725 (73.5%) received reperfusion therapy (70.8% fibrinolysis, 2.6% primary angioplasty). The adjusted odds ratio of reperfusion therapy fell 4% with each 1% increase in baseline risk of death (adjusted OR 0.96, 95% CI 0.92 to 1.00, P=0.04) and fell 18% with each additional pre-existing condition (adjusted OR 0.82, 95% CI 0.76 to 0.90, P<0.001). The number rather than the type of pre-existing conditions inversely correlated with the use of reperfusion therapy. While the impact of baseline risk and pre-existing conditions was additive, pre-existing conditions exerted a greater impact on the nonuse of reperfusion therapy than did baseline risk., Conclusions: A treatment-risk paradox is demonstrable even within a cohort of lower risk patients with ST segment elevation myocardial infarction. These findings are consistent with the view that these clinical decisions are more likely to be attributable to concerns about patient frailty or side effects than to a misunderstanding of treatment benefits.

Background: Gradients that link socioeconomic status and cardiovascular mortality have been observed in many populations, including those of countries that provide publicly funded comprehensive medical coverage. The intermediary causes of such gradients remain poorly elucidated., Objective: To examine the relationships among socioeconomic status, other health factors, and 2-year mortality rates after acute myocardial infarction (MI)., Design: Prospective cohort study., Setting: Ontario, Canada., Patients: 3407 patients who were hospitalized for acute MI in 53 large-volume hospitals in Canada from December 1999 to February 2003., Measurements: The authors obtained self-reported measures of income and education and developed profiles of the patients' prehospitalization cardiac risks and comorbid conditions. To create these profiles, the authors used the patients' self-reports and retrospectively linked no less than 12 years' worth of previous hospitalization data. Mortality rates 2 years after acute MI were examined with and without sequential risk adjustment for age, sex, ethnicity, social support, cardiovascular history and risk, comorbid conditions, and selected in-hospital process factors., Results: Income was strongly and inversely correlated with 2-year mortality rate (crude hazard ratio for high-income vs. low-income tertile, 0.45 [95% CI, 0.35 to 0.57]; P < 0.001). However, after adjustment for age and preexisting cardiovascular events or conventional vascular risk factors, the effect of income was greatly attenuated (adjusted hazard ratio for high-income vs. low-income tertile, 0.77 [CI, 0.54 to 1.10]; P = 0.150). Noncardiovascular comorbid conditions and in-hospital process factors had negligible explanatory effect., Limitations: Previous cardiovascular risks were ascertained through self-report or retrospectively through the longitudinal tracking of the hospitals' administrative databases. The study began with a cohort of patients who had an index cardiac event rather than with asymptomatic individuals., Conclusions: Age, past cardiovascular events, and current vascular risk factors accounted for most of the income-mortality gradient after acute MI. This observation suggests that the "wealth-health gradient" in cardiovascular mortality may be partially ameliorated by more rigorous management of known risk factors among less affluent persons. *For a list of members of the SESAMI Study Group, see the Appendix.

Context: Hospital report cards usually are based on administrative discharge abstracts. However, cardiac severity and comorbidities generally are under-reported in administrative data., Objective: We sought to determine how undercoding of cardiac severity and comorbidities affects the determination that some hospitals are high-mortality outliers., Design: Simulations using retrospective data on 18,795 patients admitted with an acute myocardial infarction (AMI) to 109 acute care hospitals in Ontario., Main Outcome Measure: Change in the number of hospitals that remained high-mortality outliers after adjusting for potentially increased prevalence of as many as 9 separate measures of cardiac severity and comorbid conditions, individually or together., Results: For most measures of cardiac severity and comorbidities, increasing the prevalence of each factor to the highest observed hospital-specific prevalence seldom altered the status of high-mortality outlier hospitals. Increases in the prevalence of cardiogenic shock or acute renal failure to even the median level led to reclassification of up to 4 of the 12 high-mortality outlier hospitals to nonoutlier status. Most high-mortality outlier hospitals were reclassified if the maximum prevalence was imputed for these 2 factors. Simultaneously increasing the prevalence of all comorbidities to the median level typically converted the status of about half the outlier hospitals. Not until the prevalence of all measures of cardiac severity and comorbidities were simultaneously increased to the maximum observed hospital-specific prevalence, did all hospitals initially classified as high-mortality outliers revert to nonoutlier status., Conclusions: Undercoding of severity and comorbidities in administrative data in itself is very unlikely to account for the outlier status of most hospitals. However, some potential for misclassification of individual institutions exists if influential factors are variably coded.

Background: Survival after acute myocardial infarction (AMI) varies with socioeconomic status. It is unknown whether these differences can be attributed, in part, to variations in the prevalence of atherogenic risk factors preceding the index AMI event., Objectives: To examine how cardiovascular risk factors varied according to person-level indicators of income and education among a cohort of younger patients (younger than 65 years of age) hospitalized with AMI in Ontario., Methods: The Socio-Economic and Acute Myocardial Infarction study (SESAMI) prospectively assembled a cohort of 3335 patients hospitalized with AMI who consented to participate (75% consent rate) from 53 of 57 large-volume institutions (100 AMI cases per year or more) throughout Ontario between December 1, 1999, and June 1, 2002. Given the known challenges inherent in characterizing the socioeconomic status in elderly patients and the ubiquity of atherosclerosis in elderly persons, the study focused on 1635 nonelderly participants. The relationship between income or education and cardiovascular risk factors, after adjustment for age, sex, ethnoracial factors and geography (urban-rural status) was examined., Results: The prevalence of diabetes, hypertension, smoking and pre-existing heart disease was higher among poorer, less educated patients, as were the total number of cardiovascular risk factors. After adjusting for baseline factors, both income (adjusted OR 0.50, 95% CI 0.31 to 0.82, P=0.006) and education (adjusted OR 0.52, 95% CI 0.31 to 0.87, P=0.01) were independently associated with cardiovascular risk factors or pre-existing heart disease. There were no significant interactions between income, education and baseline cardiovascular risk., Conclusions: Outcome differences across socioeconomic strata following AMI may reflect major income- and education-related differences in atherogenic risk profile.

Background: In a previous substudy of the GUSTO-I trial, we observed better functional and quality-of-life outcomes among patients in the United States (US patients) compared with patients in Canada. Rates of invasive therapy were significantly higher in the United States and were associated with a small mortality benefit (0.4%, adjusted P=0.02). We sought to determine whether Canadian-US differences in practice patterns in GUSTO-I had an impact on 5-year mortality., Methods and Results: Mortality data for 23,105 US and 2898 Canadian patients enrolled in GUSTO-I were obtained from national mortality databases. Median follow-up was 5.46 years in the US and 5.33 years in the Canadian cohort. Five-year mortality rate was 19.6% among US and 21.4% among Canadian patients (P=0.02). After baseline adjustment, enrollment in Canada was associated with a higher hazard of death (1.17; 95% confidence interval, 1.07 to 1.28, P=0.001). Revascularization rates during the index hospitalization in the United States were almost 3 times those in Canada: 30.5% versus 11.4% for angioplasty and 13.1% versus 4.0% for bypass surgery (P<0.01 for both). After accounting for revascularization status as a time-dependent covariate, country was no longer a significant predictor of long-term mortality. These results were confirmed in a propensity-matched analysis., Conclusions: Our results suggest, for the first time, that the more conservative pattern of care with regard to early revascularization in Canada for ST-segment elevation acute myocardial infarction may have a detrimental effect on long-term survival. Our results have important policy implications for cardiac care in countries and healthcare systems wherein use of invasive procedures is similarly conservative.

Context: Some have argued that Canada's uniquely restrictive approach to private health insurance keeps the socioeconomic elite inside the public system so that their demands and influence elevate the standard of service for all Canadian citizens. The extent to which this theory is a valid representation of Canadian health care is unknown., Objectives: To explore how patients with acute myocardial infarction from different socioeconomic backgrounds perceive their care in Canada's universal health care system and to correlate patients' backgrounds and perceptions with actual care received., Design, Setting, and Patients: Prospective observational cohort study with follow-up telephone interviews of 2256 patients 30 days following acute myocardial infarction discharged from 53 hospitals across Ontario, Canada, between December 1999 and June 2002., Main Outcome Measures: Postdischarge use of cardiac specialty services; satisfaction with care; willingness to pay directly for faster service or more choice; and mortality according to income and education, adjusted for age, sex, ethnicity, clinical factors, onsite angiography capacity at the admitting hospital, and rural-urban residence., Results: Compared with patients in lower socioeconomic strata, more affluent or better educated patients were more likely to undergo coronary angiography (67.8% vs 52.8%; P<.001), receive cardiac rehabilitation (43.9% vs 25.6%; P<.001), or be followed up by a cardiologist (56.7% vs 47.8%; P<.001). Socioeconomic differences in cardiac care persisted after adjustment for confounders. Despite receiving more specialized services, patients with higher socioeconomic status were more likely to be dissatisfied with their access to specialty care (adjusted RR, 2.02; 95% confidence interval, 1.20-3.32) and to favor out-of-pocket payments for quicker access to a wider selection of treatment options (30% vs 15% for patients with household incomes of Can 60 000 dollars or higher vs less than Can 30 000 dollars, respectively; P<.001). After adjusting for baseline characteristics, socioeconomic status was not significantly associated with mortality at 1 year following hospitalization for myocardial infarction., Conclusions: Compared with those with lower incomes or less education, upper middle-class Canadians gain preferential access to services within the publicly funded health care system yet remain more likely to favor supplemental coverage or direct purchase of services.

Objectives: This study was designed to determine whether admission to a Canadian hospital with on-site revascularization (invasive hospital) affected revascularization choice, timing, and outcome compared with community (non-invasive) hospitals., Background: Health care systems in Canada are characterized by relative restraint in diffusion of tertiary cardiovascular services, with capacity for revascularization procedures concentrated in large regional referral centers., Methods: We used linked administrative data and a clinical registry to follow-up 15,166 Ontario patients who underwent revascularization within the year after their index acute myocardial infarction (MI). Outcomes included recurrent urgent cardiac hospitalization, hospital bed-days, and death within the same year after the index admission. We adjusted for age, gender, socioeconomic status, illness severity, attending physician specialty, and academic hospital affiliation., Results: After adjusting for baseline factors, patients admitted to invasive hospitals were more likely to receive angioplasty than bypass surgery (adjusted odd ratio: 1.85; 95% confidence interval: 1.68 to 2.04, p < 0.001). The converse pattern was seen for patients admitted to community hospitals. Median revascularization waiting times were significantly shorter at invasive hospitals (12 vs. 48 days, p < 0.001). Patients admitted to invasive hospitals had fewer cardiac re-admissions (41.5 vs. 68.9 events per 100 patients, p < 0.001) before their first revascularization and consumed fewer hospital bed-days (379 vs. 517 per 100 patients, p < 0.001). There were no differences in outcomes beyond revascularization., Conclusions: Outcome advantages associated with timely post-MI revascularization highlight the importance of organizing revascularization referral networks and facilitating access to revascularization for patients with acute coronary syndromes admitted to community hospitals in Canada.

Background: Socioeconomic status appears to be an important predictor of coronary angiography use after acute myocardial infarction. One potential explanation for this is that patients with lower socioeconomic status live in neighbourhoods near nonteaching hospitals that have no catheterization capacity, few specialists and lower volumes of patients with acute myocardial infarction. This study was conducted to determine whether the impact of socioeconomic status on angiography use would be lessened by considering variations in the supply of services., Methods: We examined payment claims for physician services, hospital discharge abstracts and vital status data for 47 036 patients with acute myocardial infarction admitted to hospitals in Ontario between April 1994 and March 1997. Neighbourhood income of each patient was obtained from Canada's 1996 census. Using multivariate hierarchical logistic regression and adjusting for baseline patient and physician factors, we examined the interaction among hospital and regional characteristics, socioeconomic status and angiography use in the first 90 days after admission to hospital for acute myocardial infarction., Results: Within each hospital and geographic subgroup, crude rates of angiography rose progressively with increases in neighbourhood income. After adjusting for sociodemographic, clinical and physician characteristics, hospitals with on-site angiography capacity (adjusted odds ratio [OR] 1.88, 95% confidence interval [CI] 1.52-2.33), those with university affiliations (adjusted OR 1.60, 95% CI 1.27-2.01) and those closest to tertiary institutions (adjusted OR 1.57, 95% CI 1.32-1.87) were all associated with higher 90-day angiography use after acute myocardial infarction. However, the relative impact of socioeconomic status on 90-day angiography use was similar whether or not hospitals had on-site procedural capacity (interaction term p = 0.68), had university affiliations (interaction term p = 0.99), were near tertiary facilities (interaction term p = 0.67) or were in rural or urban regions (interaction term p = 0.90)., Interpretation: Socioeconomic status was as important a predictor of angiography use in hospitals with ready access to cardiac catheterization facilities as it was in those without. The socioeconomic gradient in the use of angiography after acute myocardial infarction cannot be explained by the distribution of specialists or tertiary hospitals.

Background: Data on non-Q myocardial infarctions (MI) are derived primarily from prethrombolytic era studies. Previous trials demonstrated different development rates and none reported on clinical outcomes., Methods: Our goal was to determine the incidence and prognosis of non-Q-wave MI among patients with ST-segment elevation receiving thrombolysis. A retrospective analysis of 5 randomized controlled trials was made. The main outcome measures included rates of (1) transformation of ST-segment elevation to Q- and non-Q-wave MI and (2) inhospital and 1-year mortality and reinfarction among patients who subsequently develop a Q or non-Q MI postthrombolysis as compared to controls., Results: Non-Q wave development was greater among patients receiving thrombolysis versus placebo/control (3.1% absolute difference, 95% CI 1.2%-5.0%). Among patients receiving thrombolysis, those who developed a non-Q MI experienced significantly lower inhospital and 1-year mortality (absolute differences -3.8% [95% CI -5.2% to -2.4%] and -6.4% [95% CI -9.9% to -3.0%], respectively) and reinfarction (absolute differences -2.9% [95% CI -4.3% to -1.6%] and -3.5% [95% CI -6.1% to -0.9%], respectively) rates, compared with those who evolved a Q MI. Inhospital and 1-year mortality was also significantly lower when compared to placebo/control patients who developed a non-Q MI (absolute differences 4.6% [95% CI -8.2% to -1.1%] and -7.5% [95% CI -12.5% to -2.5%], respectively)., Conclusions: Patients receiving thrombolysis more often develop a non-Q-wave MI and have a better prognosis than either those who develop a Q MI postthrombolysis or a non-Q MI after standard medical therapy.

Objectives: The goal of our study was to examine how age and gender affect the use of coronary angiography and the intensity of cardiac follow-up care within the first year after acute myocardial infarction (AMI). Another objective was to evaluate the association of age, gender and treatment intensity with five-year survival after AMI., Background: Utilization rates of specialized cardiac services inversely correlate with age. Gender-specific practice patterns may also vary with age in a manner similar to known age-gender survival differences after AMI., Methods: Using linked population-based administrative data, we examined the association of age and gender with treatment intensity and long-term survival among 25,697 patients hospitalized with AMI in Ontario between April 1, 1992, and December 31, 1993. A Cox proportional hazards model was used to adjust for socioeconomic status, illness severity, attending physician specialty and admitting hospital characteristics., Results: After adjusting for baseline differences, the relative rates of angiography and follow-up specialist care for women relative to men, respectively, fell 17.5% (95% confidence interval [CI], 13.6 to 21.3, p < 0.001) and 10.2% (95% CI, 7.1 to 13.2, p < 0.001) for every 10-year increase in age. Conversely, long-term AMI survival rates in women relative to men improved with increasing age, such that the relative survival in women rose 14.2% (95% CI, 10.1 to 17.5, p < 0.001) for every 10-year age increase., Conclusions: Gender differences in the intensity of invasive testing and follow-up care are strongly age-specific. While care becomes progressively less aggressive among older women relative to men, survival advantages track in the opposite direction, with older women clearly favored. These findings suggest that biology is likely to remain the main determinant of long-term survival after AMI for women.

Background: Critics of "scorecard medicine" often highlight the incompleteness of risk-adjustment methods used when accounting for baseline patient differences. Although socioeconomic status is a highly important determinant of adverse outcome for patients admitted to the hospital with acute myocardial infarction, it has not been used in most risk-adjustment models for cardiovascular report cards., Objectives: To determine the incremental impact of socioeconomic status adjustments on age, sex, and illness severity for hospital-specific 30-day mortality rates after acute myocardial infarction., Methods: The authors compared the absolute and relative hospital-specific 30-day acute myocardial infarction mortality rates in 169 hospitals throughout Ontario between April 1, 1994 and March 31, 1997. Patient socioeconomic status was characterized by median neighborhood income using postal codes and 1996 Canadian census data. They examined two risk-adjustment models: the first adjusted for age, sex, and illness severity (standard), whereas the second adjusted for age, sex, illness severity, and median neighborhood income level (socioeconomic status)., Results: There was an extremely strong correlation between 'standard' and 'socioeconomic status' risk-adjusted mortality rates (r = 0.99). Absolute differences in 30-day risk-adjusted mortality rates between the socioeconomic status and standard risk-adjustment models were small (median, 0.1%; 25th-75th percentile, 0.1-0.2). The agreement in the quintile rankings of hospitals between the socioeconomic status and standard risk-adjustment models was high (weighted kappa = 0.93)., Conclusion: Despite its importance as a determinant of patient outcomes, the effect of socioeconomic status on hospital-specific mortality rates over and above standard risk-adjustment methods for acute myocardial infarction hospital profiling in Ontario was negligible.

Context: Many studies have found that patients with acute myocardial infarction (AMI) who are admitted to hospitals with on-site revascularization facilities have higher rates of invasive cardiac procedures and better outcomes than patients in hospitals without such facilities. Whether such differences are due to invasive procedure rates alone or to other patient, physician, and hospital characteristics is unknown., Objective: To determine whether invasive procedural rate variations alone account for outcome differences in patients with AMI admitted to hospitals with or without on-site revascularization facilities., Design: Retrospective, observational cohort study using linked population-based administrative data from a universal health insurance system., Setting: One hundred ninety acute care hospitals in Ontario, 9 of which offered invasive procedures., Patients: A total of 25 697 patients hospitalized with AMI between April 1, 1992, and December 31, 1993, of whom 2832 (11%) were in invasive hospitals., Main Outcome Measures: Mortality, recurrent cardiac hospitalizations, and emergency department visits in the 5 years following the index admission, adjusted for patient age, sex, socioeconomic status, illness severity, and index revascularization procedures; attending physician specialty; and hospital volume, teaching status, and geographical proximity to invasive-procedure centers and compared by hospital type., Results: Patients admitted to invasive-procedure hospitals were much more likely to undergo revascularization (11.4% vs 3.2% at other hospitals; P<.001). However, many other clinical and process-related factors differed between the 2 groups. Although mortality rates were similar between the 2 institution types, the nonfatal composite 5-year event rate (ie, recurrent cardiac hospitalization and emergency department visits) was lower for patients initially admitted to invasive-procedure hospitals (71.3% vs 80.4%; unadjusted odds ratio [OR], 0.65; 95% confidence interval [CI], 0.52-0.82; P<.001). This advantage persisted after adjustment for sociodemographic and clinical factors and procedure utilization (adjusted OR, 0.68; 95% CI, 0.53-0.89; P<.001). However, the nonfatal outcome advantages of invasive-procedure hospitals were explained by their teaching status (adjusted OR, 0.98; 95% CI, 0.73-1.30; P =.87)., Conclusions: In this sample of patients admitted with AMI, the differing outcomes of apparently similar patients treated in 2 different practice settings were explained by multiple competing factors. Researchers conducting observational studies should be cautious about attributing patient outcome differences to any single factor.

The objective of this study was to compare the classification of hospitals as outcomes outliers using a commonly implemented frequentist statistical approach vs. an implementation of Bayesian hierarchical statistical models, using 30-day hospital-level mortality rates for a cohort of acute myocardial infarction patients as a test case. For the frequentist approach, a logistic regression model was constructed to predict mortality. For each hospital, a risk-adj usted mortality rate was computed. Those hospitals whose 95% confidence interval, around the risk-adjusted mortality rate, excludes the mean mortality rate were classified as outliers. With the Bayesian hierarchical models, three factors could vary: the profile of the typical patient (low, medium or high risk), the extent to which the mortality rate for the typical patient departed from average, and the probability that the mortality rate was indeed different by the specified amount. The agreement between the two methods was compared for different patient profiles, threshold differences from the average and probabilities. Only marginal agreement was shown between the Bayesian and frequentist approaches. In only five of the 27 comparisons was the kappa statistic at least 0.40. The remaining 22 comparisons demonstrated only marginal agreement between the two methods. Within the Bayesian framework, hospital classification clearly depended on patient profile, threshold and probability of exceeding the threshold. These inconsistencies raise questions about the validity of current methods for classifying hospital performance, and suggest a need for urgent research into which methods are most meaningful to clinicians, managers and the general public.

Background: Many older people do not receive beta-blocker therapy after myocardial infarction or receive doses lower than those tested in trials, perhaps because physicians fear that beta-blockers may precipitate heart failure. We examined the relation between use of beta-blockers, the dose used, and hospital admission for heart failure and 1-year survival in a cohort of all older patients surviving myocardial infarction in Ontario, Canada., Methods: We collected data on a cohort of 13,623 patients aged 66 years or older who were discharged from hospital after a myocardial infarction and who did not receive beta-blocker therapy or received low, standard, or high doses. We used Cox's proportional-hazards models to study the association of dose with admission for heart failure and survival with adjustment for factors including age, sex, and comorbidity., Findings: Among 8232 patients with no previous history of heart failure, dispensing of beta-blocker therapy was associated with a 43% reduction in subsequent admission for heart failure (adjusted risk ratio 0.57 [95% CI 0.48-0.69]) compared with patients not dispensed this therapy. Among the 4681 patients prescribed beta-blockers, the risk of admission was greater in the high-dose than in the low-dose group (1.53 [1.01-2.31]). Among all 13,623 patients in the cohort, 2326 (17.1%) died by 1 year. Compared with those not dispensed beta-blocker therapy, the adjusted risk ratio for mortality was lower for all three doses (low 0.40 [0.34-0.47], standard 0.36 [0.31-0.42], high 0.43 [0.33-0.56])., Interpretation: Compared with high-dose beta-blocker therapy, low-dose treatment is associated with a lower rate of hospital admission for heart failure and has a similar 1-year survival benefit. Our findings support the need for a randomised controlled trial comparing doses of beta-blocker therapy in elderly patients.

Background: The objective of this study was to determine how subgroup analyses are performed in large randomized trials of cardiovascular pharmacotherapy., Methods and Results: We reviewed 67 randomized, double-blind, controlled trials involving pharmacotherapy in at least 1000 patients with unstable angina, myocardial infarction, left ventricular dysfunction, or heart failure with clinical outcomes as primary end points, published between 1980 and 1997. Nine had no subgroup analyses but 43 reported on 5 or more subgroups and 31 reported subgroups without formal statistical tests for treatment-subgroup interactions. In most trials, a rationale for subgroup selection was missing. All but 6 focused on single-factor subgroups., Conclusions: Trial subgroups should ideally be defined a priori on 2 bases: single-factor subgroups with a strong rationale for biological response modification and multifactorial prognostic subgroups defined from baseline risks. However, single-factor subgroup analyses are often reported without a supporting rationale or formal statistical tests for interactions. We suggest that clinicians should interpret published subgroup-specific variations in treatment effects skeptically unless there is a prespecified rationale and a significant treatment-subgroup interaction.

Background: Deaths among patients awaiting coronary artery bypass grafting (CABG) are a source of private grief and public concern in Canada. However, some deaths are expected over time among patients with coronary artery disease. Methods of benchmarking the burden of delayed care may be useful in understanding and managing waiting lists for CABG and other health services. The authors therefore determined the vital risk among people waiting for CABG in Ontario and compared it with the risk in the general population and among people living with coronary artery disease., Methods: Patients registered to undergo CABG in Ontario between 1991 and 1995 were followed to ascertain numbers and dates of preoperative deaths or completed operations. Linking hospital discharge abstract data to vital statistics for 1991 to 1994, the authors defined a cohort of people who had survived 6 months after an acute myocardial infarction (AMI) and followed them for an additional 6 months to determine numbers and dates of deaths. They matched patients by age and sex and then calculated the standardized mortality ratio for each cohort (i.e., the ratio of observed deaths to those expected based on age- and sex-specific daily probabilities of death for the provincial population)., Results: Among 21,220 patients awaiting CABG, there were 82 preoperative deaths over a median follow-up of 18 days; the standardized mortality ratio was 2.92 (95% confidence limit [CL] 2.29-3.55). Among 21,220 matched 6-month survivors of an AMI, there were 663 deaths over a median follow up of 185 days; the standardized mortality ratio was 3.84 (95% CI 3.54-4.14)., Interpretation: Patients awaiting CABG in Ontario are at a much greater risk of death than the general population. However, when compared with thousands of other patients living with coronary artery disease, they are at similar or decreased vital risk.

Background: There is relatively little information available on recent population-based trends in the outcomes of patients who have had an acute myocardial infarction (AMI). We, therefore, conducted a study of temporal trends in the outcomes of AMI patients in Ontario, Canada, between the 1992 and 1996 fiscal years., Methods: 114,618 AMI patients were discharged from hospitals in Ontario between Apr. 1, 1992, and Mar. 31, 1997. After specific exclusion criteria were applied the final sample of 89,456 patients was divided into 5 cohorts according to the fiscal year of discharge. As part of the Ontario Myocardial Infarction Database project the linked administrative data pertaining to these patients were used to examine cohort characteristics, cardiac procedures used and mortality rates for each of the 5 cohorts over time., Results: There was a significant increase in the percentage of patients in Ontario receiving coronary angiography, percutaneous transluminal coronary angioplasty and coronary artery bypass grafting surgery (p < 0.001) after an AMI between 1992 and 1996. In addition, the overall 30-day risk-adjusted mortality rate declined from 15.5% in 1992 to 14.0% in 1996 (p = 0.001) and the 1-year risk-adjusted mortality rate declined from 23.7% in 1992 to 22.3% in 1996 (p = 0.017). Virtually all of the improvement occurred within 30 days of admission. The absolute decline in 1-year mortality rates was significant for patients under the age of 65 (2.3%, 95% confidence interval [CI] 1.4% to 3.2%) and for males (1.2%, 95% CI 0.2% to 2.2%); absolute declines were not significant for patients 65 years of age or older (0.7%, 95% CI -0.6% to 2.0%) and for female patients (-0.1%, 95% CI -1.7% to 1.5%). Interestingly, post-infarction coronary angiography and coronary artery bypass grafting rates were consistently lower in the older and the female patients throughout the study period., Interpretation: There was a modest improvement in the short- and long-term survival of patients in Ontario after an AMI between 1992 and 1996. The Ontario experience suggests that recent advances in AMI management have been of more benefit to younger and male AMI patients.

Background: Universal health care systems seek to ensure access to care on the basis of need rather than income and to improve the health status of all citizens. We examined the performance of the Canadian health system with respect to these goals in the province of Ontario by assessing the effects of neighborhood income on access to invasive cardiac procedures and on mortality one year after acute myocardial infarction., Methods: We linked claims for payment for physicians' services, hospital-discharge abstracts, and vital-status data for all patients with acute myocardial infarction who were admitted to hospitals in Ontario between April 1994 and March 1997. Patients' income levels were imputed from the median incomes of their residential neighborhoods as determined in Canada's 1996 census. We determined rates of use and waiting times for coronary angiography and revascularization procedures after the index admission for acute myocardial infarction and determined death rates at one year. In multivariate analyses, we controlled for the patient's age, sex, and severity of disease; the specialty of the attending physician; the volume of cases, teaching status, and on-site facilities for cardiac procedures at the admitting hospital; and the geographic proximity of the admitting hospital to tertiary care centers., Results: The study cohort consisted of 51,591 patients. With respect to coronary angiography, increases in neighborhood income from the lowest to the highest quintile were associated with a 23 percent increase in rates of use and a 45 percent decrease in waiting times. There was a strong inverse relation between income and mortality at one year (P<0.001). Each $10,000 increase in the neighborhood median income was associated with a 10 percent reduction in the risk of death within one year (adjusted hazard ratio, 0.90; 95 percent confidence interval, 0.86 to 0.94)., Conclusions: In the province of Ontario, despite Canada's universal health care system, socioeconomic status had pronounced effects on access to specialized cardiac services as well as on mortality one year after acute myocardial infarction.

Objectives: We assessed the use and effects of acute intravenous and later oral atenolol treatment in a prospectively planned post hoc analysis of the GUSTO-I dataset., Background: Early intravenous beta blockade is generally recommended after myocardial infarction, especially for patients with tachycardia and/or hypertension and those without heart failure., Methods: Besides one of four thrombolytic strategies, patients without hypotension, bradycardia or signs of heart failure were to receive atenolol 5 mg intravenously as soon as possible, another 5 mg intravenously 10 min later and 50 to 100 mg orally daily during hospitalization. We compared the 30-day mortality of patients given no atenolol (n=10,073), any atenolol (n=30,771), any intravenous atenolol (n=18,200), only oral atenolol (n=12,545) and both intravenous and oral drug (n=16,406), after controlling for baseline differences and for early deaths (before oral atenolol could be given)., Results: Patients given any atenolol had a lower baseline risk than those not given atenolol. Adjusted 30-day mortality was significantly lower in atenolol-treated patients, but patients treated with intravenous and oral atenolol treatment vs. oral treatment alone were more likely to die (odds ratio, 1.3; 95% confidence interval, 1.0 to 1.5; p=0.02). Subgroups had similar rates of stroke, intracranial hemorrhage and reinfarction, but intravenous atenolol use was associated with more heart failure, shock, recurrent ischemia and pacemaker use than oral atenolol use., Conclusions: Although atenolol appears to improve outcomes after thrombolysis for myocardial infarction, early intravenous atenolol seems of limited value. The best approach for most patients may be to begin oral atenolol once stable.

Background: Acute myocardial infarction is a leading cause of morbidity and mortality in the United States and Canada. We performed a population-based study to compare the use of cardiac procedures and outcomes after acute myocardial infarction in elderly patients in the two countries., Methods: We compared the use of invasive cardiac procedures and the mortality rates among 224,258 elderly Medicare beneficiaries in the United States and 9444 elderly patients in Ontario, Canada, each of whom had a new acute myocardial infarction in 1991., Results: The U.S. patients were significantly more likely than the Canadian patients to undergo coronary angiography (34.9 percent vs. 6.7 percent, P< 0.001), percutaneous transluminal coronary angioplasty (11.7 percent vs. 1.5 percent, P<0.001), and coronary-artery bypass surgery (10.6 percent vs. 1.4 percent, P<0.001) during the first 30 days after the index infarction. These differences in the use of cardiac procedures narrowed but persisted through 180 days of follow-up. The 30-day mortality rates were slightly but significantly lower for the U.S. patients than for the Canadian patients (21.4 percent vs. 22.3 percent, P=0.03). However, the one-year mortality rates were virtually identical (34.3 percent in the United States vs. 34.4 percent in Ontario, P= 0.94)., Conclusions: Short-term mortality after an acute myocardial infarction was slightly lower in the United States than in Ontario, but these differences did not persist through one year of follow-up. The strikingly higher rates of use of cardiac procedures in the United States, as compared with Canada, do not appear to result in better long-term survival rates for elderly U.S. patients with acute myocardial infarction.

Objective: To pilot-test a simple checklist designed to improve coding of acute myocardial infarction (AMI) in hospital discharge abstracts., Background: Health records technologists review hospital charts to code discharge diagnoses according to the International Classification of Diseases, 9th revision (ICD-9). Many studies have suggested that there is a high false positive rate in coding AMI, ie, ICD-9 410, on hospital discharge abstracts., Patients and Methods: The checklist required either at least two of suggestive symptoms, diagnostic electrocardiographic changes, or diagnostic rise in serum cardiac enzymes; or confirmation by autopsy. First case of use was confirmed-typical time to complete the checklist was 3 to 4 mins. Then 16 Ontario community hospitals were recruited to apply the checklist on a blinded basis to 1000 randomly drawn in-patient records-10% were audited for another study to confirm AMI; and 90% were originally coded with 'most responsible diagnosis' (MRD) of AMI, other cardiovascular diagnoses and various noncardiac conditions. Percentage agreement (95% CI) between the checklist and the confirmed or coded diagnosis was analyzed; coding of AMI as a secondary diagnosis was examined in further analyses., Results: One hospital withdrew for logistical reasons; the final useable sample from 15 hospitals was 943 records. The checklist correctly identified 100% of AMIs independently confirmed for another study; usual coding identified 89.7% of cases (70 of 78; 95% CI 80.8 to 95.5). For cases not confirmed, but where the physician had nonetheless diagnosed AMI, six of 11 charts were miscoded as AMI in hospital records; none were miscoded by the checklist. For records with AMI as MRD, 11.6% (44 of 380; 95% CI 8.5 to 15.2) were classified as false positives by the checklist. Where an AMI was coded as a secondary diagnosis, 52.9% (36 of 68; 95% CI 40.5 to 65.2) met the checklist criteria for AMI. Finally, among records where the MRD was other than AMI, 6.8% (38 of 563; 95% CI 4.8 to 9.2) met checklist criteria for AMI during admission, but 94.7% had an ICD-9410 code as a secondary diagnosis., Conclusion: A simple checklist can be very easily applied, has extremely high sensitivity for confirming the presence of AMI, and identifies a clinically significant proportion of charts with false positive codes for AMI. Conversely, these findings support the high sensitivity (low false negative rates) of conventional coding practices for AMI in Canadian hospital records, be it as a primary or secondary diagnosis (eg, 95% detection rate). Usual coding, combined with the checklist for tentative ICD-9 410 diagnoses, would improve the accuracy of Canadian hospital records.

Objective: The Warm Heart Investigators Trial randomized isolated coronary bypass patients to cold or warm cardioplegia, and demonstrated that warm cardioplegia significantly reduced the prevalence of low output syndrome and myocardial infarction (as defined by CKMB enzyme release). This study was designed prospectively as a subanalysis of the original trial, to determine the effect of warm heart surgery on high risk patients, who were anticipated to derive the major benefit from warm cardioplegia., Methods: The prespecified endpoint for this study was a composite outcome of morbidity and mortality (death and/or low output syndrome and/or enzymatic myocardial infarction). Only patients with complete data for all outcomes were included, totalling 1374 patients (692 warm cardioplegia, 682 cold cardioplegia) who were randomized in the Warm Heart Investigators Trial. High medium and low risk patients were identified by a multivariate model of predicted risk for the study outcome., Results: Analysis of the independent and interactive influence of cardioplegia technique and predicted risk demonstrated that warm cardioplegia significantly reduced the overall prevalence of morbidity and mortality (warm: 15.9 versus cold: 25.2%, P < 0.01). However, no significant differences in warm-cold effects were detected among risk terciles. Cardioplegia technique had a similar differential influence on mortality and morbidity in low risk patients (warm: 7.3, cold: 17.4%) as it did in high risk patients (warm: 31.1, cold: 39.9%)., Conclusions: Although our analysis confirms the overall benefits of warm cardioplegia, our unanticipated finding in high risk subjects may be explained by the fact that morbidity and mortality in that patient subgroup is caused not only by poor myocardial protection, but by other clinical and technical factors. Further studies are necessary to identify those patients who might benefit most from improved myocardial protection techniques.

Objectives: To characterize the extent of delay in administration of thrombolytic therapy to patients with acute myocardial infarction (AMI) in Canada, to examine patient-specific predictors of such delay and to measure the effect of delay on short-term nonfatal cardiac outcomes., Design: Secondary cohort analysis of data from the first international Global Utilization of Streptokinase and tPA for Occluded Coronary Arteries (GUSTO-I) trial., Setting: Sixty-three acute care hospitals across Canada., Subjects: All 2898 Canadian patients with an AMI enrolled in GUSTO-I., Main Outcomes: Time before arrival at a hospital ("symptom-to-door" time) and time from arrival to administration of therapy ("door-to-needle" time) for patients who had an AMI outside of a hospital, in clinically relevant categories; proportions of patients with nonfatal, serious cardiac events, including shock, sustained ventricular tachycardia, ventricular fibrillation and asystole., Results: Of the total number of patients enrolled, records were complete for 2708; 2542 of these patients (93.9%) had an AMI outside of a hospital. These 2542 patients presented a median 81 (interquartile range 50 to 130) minutes after the onset of symptoms, and the median time to treatment in hospital was 85 (interquartile range 61 to 115) minutes. Whereas a greater proportion of Canadian patients than of patients enrolled in GUSTO-I in other countries reached hospital within 2 hours of symptom onset (71.5% v. 61.2%, p < 0.001), a greater proportion of Canadian patients experienced in-hospital treatment delays of more than 1 hour (75.3% v. 57.1%, p < 0.001). In an analysis of all 2708 patients with complete records, both the unadjusted and adjusted odds of nonfatal cardiac events for those treated 4 to 6 hours after symptom onset were significantly higher than for those treated within 2 hours (odds ratio 1.60, 95% confidence interval 1.09 to 2.37)., Conclusion: After arrival at a hospital, Canadian patients enrolled in GUSTO-I received thrombolytic therapy more slowly than trial enrollees in other countries. Such delays are already known to decrease the rate of short-term survival after AMI. The findings further show that long time to treatment also increases the odds of nonfatal, serious cardiac events. Hospitals and physicians caring for patients with AMI should routinely assess whether and how they can improve door-to-needle times.

Objectives: This study was done to compare characteristics and outcomes of patients with acute myocardial infarction participating in two thrombolysis trials with those of nontrial patients at study hospitals and external hospitals., Background: Preferential recruitment of lower risk patients into randomized trials of thrombolysis has been suggested by earlier studies. However, to date there has not been a definitive population-based comparison of characteristics and outcomes for thrombolysis trial participants and nonparticipants., Methods: Population-based data on hospital admissions and mortality from acute myocardial infarction for all hospitals in Ontario from 1989 to 1992 were linked to data on trial participants in two distinct thrombolysis studies (GUSTO I and LATE). Included were 1,304 patients entered into GUSTO, 12,657 nonparticipants at GUSTO hospitals, 249 patients entered into LATE, 5,997 nonparticipants at LATE hospitals and 12,299 patients at external hospitals. The main outcomes were differences in age, gender, comorbidity scores, coronary revascularization and survival to hospital discharge., Results: Patients in both GUSTO and LATE were significantly more likely to be <70 years old (odds ratio [OR] 2.8 and 3.2, respectively), to be male (OR 2.0 and 2.1, respectively), to have low comorbidity scores (OR 2.0 and 2.3, respectively) and, for GUSTO alone, to undergo coronary revascularization (OR 2.4). Nontrial patients were similar between trial hospitals and external hospitals. In-hospital mortality rates for GUSTO and LATE patients were lower (6.9% and 6.6%, respectively) than for nonparticipants at study hospitals (16.8% and 19.7%, respectively; p<0.001 for both comparisons). Survival to hospital discharge remained higher among GUSTO (OR 1.9) and LATE patients (OR 2.0) than nonparticipants at study hospitals even after adjustment for age, gender, revascularization and comorbidity scores., Conclusions: Compared with nontrial patients, thrombolysis trial participants are younger, more often male, undergo more revascularization and have less comorbid disease. Even after adjustment for these factors, participants have a survival advantage over nonparticipants that is larger than expected from thrombolysis alone. These findings are not attributable to inferior care or skewed populations at hospitals that did not join these major trials. Further study of these selection biases may guide future trial design and deepen our understanding of why thrombolytics have been underused for high risk patients in routine practice.

Objective: To determine whether regional differences exist within Ontario in the use and timing of coronary artery bypass grafting (CABG) and percutaneous transluminal coronary angioplasty (PTCA) among patients who have recently suffered an acute myocardial infarction (AMI)., Background: Regional variations have been documented in the use of CABG in Canada, but previous findings do not fully account for either an alternative procedure (PTCA) or the impact of geographic variations in disease incidence or severity. By following persons after AMI, one can address both issues simultaneously in a subpopulation of patients where substitution of PTCA for CABG may be occurring., Patients and Methods: Hospital discharge abstracts were used to define an inception cohort of 6565 patients with a primary diagnosis of AMI in the first six months of fiscal 1990. Subjects were tracked longitudinally for subsequent CABG or PTCA over the remainder of the fiscal year. Procedures were attributed by site of patient residence to one of five major Ontario referral regions. Proportions of patients undergoing revascularization and time in days from AMI to intervention were compared by chi 2 tests and nonparametric analysis of variance, respectively., Results: Overall, 9.7% of patients underwent revascularization, with regional rates ranging from 7.2 to 13.6% (P < 0.0001). Elapsed time to revascularization also varied by region (P < 0.01). Use of CABG and PTCA varied separately by region (both P < 0.0001). Two regions with significantly elevated CABG rates were statistically similar to the provincial mean for overall revascularization owing to proportionately lower use of PTCA., Conclusions: Regional variations in use and timing of coronary revascularization were evident in this post-AMI cohort. Longitudinal tracking for substitutable procedures in a defined inception cohort may yield perspectives that complement conventional small area analyses.

Background: Patients with acute myocardial infarction who were treated with accelerated tissue plasminogen activator (t-PA) (given over a period of 1 1/2 hours rather than the conventional 3 hours, and with two thirds of the dose given in the first 30 minutes) had a 30-day mortality that was 15 percent lower than that of patients treated with streptokinase in the Global Utilization of Streptokinase and Tissue Plasminogen Activator for Occluded Coronary Arteries (GUSTO) study. This was equivalent to an absolute decrease of 1 percent in 30-day mortality. We sought to assess whether the use of t-PA, as compared with streptokinase, is cost effective., Methods: Our primary, or base-case, analysis of cost effectiveness used data from the GUSTO study and life expectancy projected on the basis of the records of survivors of myocardial infarction in the Duke Cardiovascular Disease Database. In the primary analysis, we assumed that there were no additional treatment costs due to the use of t-PA after the first year and that the comparative survival benefit of t-PA was still evident one year after enrollment., Results: One year after enrollment, patients who received t-PA had both higher costs ($2,845) and a higher survival rate (an increase of 1.1 percent, or 11 per 1000 patients treated) than streptokinase-treated patients. On the basis of the projected life expectancy of each treatment group, the incremental cost-effectiveness ratio--with both future costs and benefits discounted at 5 percent per year--was $32,678 per year of life saved. The use of t-PA was least cost effective in younger patients and most cost effective in older patients. At all ages, the use of t-PA in patients with anterior infarctions yielded more favorable cost-effectiveness values. In our secondary analyses, the cost-effectiveness values were most sensitive to a lowering of the projected long-term survival benefits of t-PA and to moderate or greater increases in the projected medical costs for patients in the t-PA group after the first year. In contrast, our results were not sensitive to even very unfavorable assumptions about the additional costs associated with the higher rate of disabling stroke that was noted in patients treated with t-PA in the GUSTO study., Conclusions: The cost effectiveness of treatment with accelerated t-PA rather than streptokinase compares favorably with that of other therapies whose added medical benefit for dollars spent is judged by society to be worthwhile.

Objective: To investigate the influence of hospital teaching status and service availability on rates of revascularization following myocardial infarction., Design: Retrospective cohort study based on province-wide hospital discharge abstracts., Setting: All acute care hospitals in Ontario, Canada's most populous province (9.7 million)., Patients: Patients admitted to hospital between April 1, 1991, and September 30, 1991, with a principal diagnosis of acute myocardial infarction., Measurements: The odds of a patient's having been referred for revascularization (angioplasty or bypass surgery) within six months of a myocardial infarction were calculated based on the type of hospital to which he or she had initially presented, defined as "teaching" or "nonteaching" or as having or not having interventional facilities on-site (cardiac catheterization and/or revascularization). Odds ratios were adjusted for potential confounding variables, and for possible joint effects of teaching status and on-site interventional capabilities., Results: The patients were more likely to have had revascularization (OR 1.79; 95% CI 1.47-2.14, p = 0.0001) when they had been admitted to a teaching hospital, and independently were more likely to have been referred for revascularization (OR 1.34; 95% CI 1.09-1.66, p = 0.0067) when they had been admitted to a hospital with on-site interventional facilities. There was no interaction between teaching status and service availability regarding referral for revascularization., Conclusion: Teaching status is an important determinant of revascularization following acute myocardial infarction and is independent of service availability, which also influences revascularization rates.

Objectives: This study attempted to determine population-based trends in in-hospital patient fatality from acute myocardial infarction., Background: The in-hospital prognosis for patients with acute myocardial infarction should be improving as a result of adoption of treatments proved in randomized trials (e.g., thrombolytic, beta-adrenergic blocking and anticoagulant agents and aspirin). However, all trials are subject to selection biases, eligibility is limited for some therapies, and proved therapies may be underused even among eligible patients., Methods: Using administrative data from all general hospitals in Ontario, Canada, we analyzed 17,489, 17,839, 18,393, 18,794, 18,716 and 19,748 records of patients with a primary discharge diagnosis of myocardial infarction for fiscal years 1981, 1983, 1985, 1987, 1989 and 1991, respectively., Results: After age and gender adjustment, the overall relative reduction in in-hospital case fatality rates for the 10-year period was 26.9% (99% confidence interval [CI] 26.8% to 26.9%), corresponding to an absolute reduction of 6% (99% CI 5.6% to 6.4%). Age- and gender-standardized case fatality rate decreased from 22.3% in 1981 to 21.4% in 1985, followed by a highly significant decline to 16.3% in 1991. On the basis of the relation of comparative mortality to days of hospital stay, declining mortality was not an artifact of decreasing length of stay., Conclusions: There have been encouraging improvements in survival after acute myocardial infarction over the past 6 years. Further improvements may require development of new therapies that can be more widely applied to this patient population.

Background: Much attention has been directed to the use of medical resources and to patients' outcomes in Canada as compared with the United States. We compared U.S. and Canadian patients with respect to their use of medical resources and their quality of life during the year after acute myocardial infarction., Methods: A total of 2600 U.S. and 400 Canadian patients were randomly selected from the Global Utilization of Streptokinase and t-PA for Occluded Coronary Arteries (GUSTO) trial. Base-line data from their initial hospitalizations were analyzed, and the patients were then interviewed by telephone 30 days, 6 months, and 1 year after myocardial infarction to determine their use of medical care and quality of life., Results: The Canadian patients typically stayed in the hospital one day longer (P = 0.009) than the U.S. patients but had a much lower rate of cardiac catheterization (25 percent vs. 72 percent, P < 0.001), coronary angioplasty (11 percent vs. 29 percent, P < 0.001), and coronary bypass surgery (3 percent vs. 14 percent, P < 0.001). At one year 24 percent of the Canadian and 53 percent of the U.S. patients had undergone angioplasty or bypass surgery at least once (P < 0.001). The Canadian had more visits to physicians during the follow-up year (P < 0.001), but fewer visits to specialists (P < 0.001). At 30 days, functional status was equivalent in the patients from the two countries. However, after one year the U.S. patients had substantially more improvement than the Canadian patients (P < 0.001). The prevalence of chest pain and dyspnea at one year was higher among the Canadian patients (34 percent vs. 21 percent and 45 percent vs. 29 percent, respectively; P < 0.001)., Conclusions: The Canadian patients had more cardiac symptoms and worse functional status one year after acute myocardial infarction than the U.S. patients. The Canadian patients also underwent fewer invasive cardiac procedures and had fewer visits to specialist physicians. These results suggest, but do not prove, that the more aggressive pattern of care in the United States may have been responsible for the better quality of life.

Background: Thrombolytic therapy reduces mortality after acute myocardial infarction, even when treatment is initiated relatively late after onset of symptoms. The mechanism underlying this survival benefit is incompletely understood., Methods and Results: In a prospectively designed ancillary study of a randomized, placebo-controlled trial of late thrombolytic therapy (LATE), the signal-averaged (SA) ECG was recorded before hospital discharge in an effort to assess the effect of thrombolytic therapy on arrhythmia substrate. Three hundred ten patients were enrolled at 23 participating sites; 160 patients received placebo, and 150 patients received recombinant tissue-type plasminogen activator (rTPA) therapy 6 to 24 hours after onset of symptoms. Compared with placebo, rTPA tended to reduce the frequency of SAECG abnormality (filtered QRS duration > 120 milliseconds) by 37% (95% CI, -64%, +6%; P = .087) and the filtered QRS duration (105.7 +/- 13.8 versus 108.8 +/- 14.6 milliseconds, P = .05). In the prespecified subgroup of 185 patients with ST elevation on the qualifying ECG, rTPA resulted in a 52% reduction (95% CI, 4% to 77%, P = .011) of SAECG abnormality and a shorter filtered QRS duration (105.7 +/- 10.9 versus 110.7 +/- 15.9 milliseconds, P = .01). No benefit was seen in patients without ST elevation on ECG., Conclusions: Late thrombolytic therapy produced a more stable electrical substrate, which probably represents an important mechanism of mortality benefit.

Unexplained variation in length of stay (LOS) following acute myocardial infarction (AMI) has been observed among American hospitals. We explored this phenomenon in the universal hospital care system of Ontario, Canada's largest province, analyzing general hospital discharge abstracts for all patients with a primary diagnosis of AMI. Case homogeneity was increased by excluding inter-hospital transfers, in-hospital deaths, patients with revascularization during the index admission and patients with severe comorbid conditions. This left 11,411 records of patients in 187 hospitals from April 1, 1990 to March 31, 1991. The mean length of stay was 9.9 days with standard deviation of 3.8. Available patient and hospital characteristics explained only 12% of the individual variation in LOS. Interinstitutional variation remained highly significant after controlling for patients' characteristics within the 87 hospitals admitting more than 50 cases per annum; these hospitals accounted for 84% of the eligible provincial admissions. The grand mean length of stay for 87 hospitals was 10 days, ranging from 6.6 to 12.9 days. Stepwise multiple linear regression analyses showed that lower caseload was associated with an increased length of hospitalization. Thus, despite Ontario's uniform system of hospital funding and medical insurance, a large amount of unexplained variation in length of stay exists for patients hospitalized with AMI, affecting thousands of bed-days per annum.

Objective: To determine whether sex differences exist in the use of coronary angiography, coronary artery bypass surgery (CABS) or percutaneous transluminal coronary angioplasty (PTCA) among persons recently diagnosed with an acute myocardial infarction (AMI) in Canada., Background: A growing body of literature suggests that coronary artery disease in males is treated differently from females. Specifically, recent studies have indicated that sex may influence decisions about the use of invasive diagnostic and therapeutic coronary procedures in patients with suspected or proven coronary artery disease., Patients and Methods: The study design is a population-based inception cohort study. The data source is hospital discharges from all acute care hospitals in Ontario. The study population consisted of 6949 men and women discharged with a principal diagnosis of AMI between April 1 and September 30, 1990, and followed through record linkage until March 31, 1991 to determine whether any invasive coronary procedures were performed after their AMI. Odds ratio estimates (OR) and 95% confidence intervals (95% CI) for use of coronary angiography, CABS and PTCA in men were compared with those in women., Results: The adjusted OR for coronary angiography was 1.4 (95% CI 1.2 to 1.6), indicating that males were more likely to undergo angiography than females. A similar finding was seen for CABS (OR = 1.6, 95% CI 1.2 to 2.1), but for PTCA, the sex difference was less pronounced (OR = 1.3, 95% CI 1.0 to 1.7). Cox proportional hazards regression also was used to test the hypothesis and showed similar results., Conclusions: Women suffering AMI undergo coronary angiography and CABS at a significantly lower rate than men in Ontario, with similar trends evident in use of PTCA.

Objective: An economic evaluation of the potential incremental benefits of intravenous tissue plasminogen activator (tPA) versus streptokinase (SK) for treatment of acute myocardial infarction., Design: Cost effectiveness analysis from a third-party payer perspective (Ontario Ministry of Health). ECONOMIC INPUTS: Fully allocated costs for cardiovascular procedures and hospitalization for myocardial infarction were obtained anonymously for four Ontario teaching hospitals and converted to 1988 Canadian dollars. Professional charges were taken from the provincial health insurance fee schedule and drug costs obtained from the manufacturers. CLINICAL INPUTS: The baseline analysis was for nonelderly patients with uncomplicated myocardial infarctions; sensitivity analyses allowed extrapolation to higher risk subgroups. Short and longer term mortality and short term invasive procedure rates were estimated using data from clinical trials., Main Results: If tPA achieves a 1% short term mortality advantage over SK with no advantages for other survivors, cost per life-year gained can be comparable to other cardiovascular interventions at $58,600. In the absence of immediate survival advantages, but assuming greater left ventricular preservation, the constant annual hazard rate advantage must be about 0.5% per year for competitive cost effectiveness ratios., Conclusions: A full range of projections is presented to help guide the policy decisions that will arise in the wake of the Global Utilization of SK and tPA for Occluded Coronary Arteries (GUSTO) trial. The analysis also illustrates the general importance of considering longer term effects of in-hospital therapies for acute myocardial infarction.

A meta-analysis of randomized clinical trials of fibrinolysis was performed, examining the interaction between aspirin and fibrinolysis in treating patients with acute myocardial infarction. Reductions in the odds of death up to 35 days were assessed for patients receiving tissue plasminogen activator or streptokinase up to 6 hours after the onset of symptoms. No significant difference in effectiveness between tissue plasminogen activator and streptokinase was demonstrated. The overall reduction in odds of death due to fibrinolytic therapy was 28%. However, there was a significant difference between the odds reduction of 24% when fibrinolysis is compared to placebo, and 40% when fibrinolysis and aspirin combined are compared to aspirin alone (p = 0.02). This difference indicates that there exists a synergistic interaction between coronary fibrinolysis and aspirin rather than independence of their beneficial effects, as is generally believed. These results illustrate the perils of assessing drug efficacy, even in an overview of all relevant trials, without consideration of identifiable sources of heterogeneity such as the interaction between the treatment of interest and co-interventions. They also demonstrate the potential application of logistic regression diagnostic techniques to meta-analyses.

Hospital medical records staff enter diagnostic codes on charts using the International Classification of Diseases (Clinically Modified), Ninth Revision (ICD-9-CM). In a downtown Toronto tertiary hospital, 209 consecutive charts coded for acute myocardial infarction as the primary diagnosis in 1987-88 were reviewed. Criteria for documentation of acute myocardial infarction included symptomatic, electrocardiographic and enzymatic elements. Forty-three (21%) false-positives, ie, charts coded acute myocardial infarction where criteria were not fulfilled, were found (95% confidence interval 15 to 26%). Physician diagnosis of acute myocardial infarction appeared on the face sheet of 30 of the false-positive cases. Common reasons for false-positive face sheet entries and chart coding were acute myocardial infarction within the previous eight weeks with transfer or readmission for coronary angiography and other procedures; and presumed acute myocardial infarction on admission subsequently unproven or disproved. The false-positive proportion was similar to a Canadian study drawing on charts from hospitals of various sizes in 1977, lower than in recent reports from various American tertiary teaching hospitals (P less than 0.0001), and higher than in five Boston area community hospitals (P = 0.0005) where procedure-related transfers or readmissions of previous acute myocardial infarction patients were less likely. This audit lends credence to arguments that changes are needed in ICD-9-CM codes for acute myocardial infarction and in the assignation of reasons for hospitalization.

Evidence of the potential impact of intravenous thrombolytic therapy on short-term revascularization rates among patients with acute myocardial infarction was sought. Because nonrandomized comparisons with conventional treatment would be subject to various confounders, a meta-analysis of randomized controlled trials was performed. Seven trials were included, applying standard doses of either tissue plasminogen activator or streptokinase without an aggressive revascularization protocol. Follow-up ranged from 14 to 30 days. The revascularization rates among treated patients in all trials were lower than in the conservative arm of the Thrombolysis in Myocardial Infarction Phase II trial, which established the current procedural benchmarks for postthrombolysis management. However, the aggregate volume of bypass surgery and angioplasty in patients treated with tissue plasminogen activator was more than double that of controls (odds ratio, 2.25; 95% confidence interval, 1.31 to 3.94), with a smaller but still significant increase for streptokinase-treated patients (odds ratio, 1.66; 95% confidence interval, 1.08 to 2.59). Combining all trials, the increase in mechanical revascularization was 80% (95% confidence interval, 33% to 144%). Thus, for patterns of practice currently accepted in North America, intravenous thrombolysis for myocardial infarction leads to a significant short-term increase in clinical and angiographic indications for revascularization as compared with conventional treatment.

The Ontario Medical Association (OMA) guidelines for intravenous thrombolysis in acute myocardial infarction were released in March 1988 and contributed to a government decision against special per-case funding to assist hospitals using tissue-type plasminogen activator (tPA). In October 1988, 1512 cardiologists, internists and physician-administrators who were OMA members were mailed a questionnaire seeking their views on the OMA guidelines and related issues. Of the 419 questionnaires (28%) that were returned, 392 contained usable responses. Among the respondents 268 (68%) had used thrombolytic drugs in the preceding 12 months; the mean number of cases was 10.6 (standard deviation 12.9). A strong or a mild preference for tPA over streptokinase was registered by 64% of the respondents; 28% had no preference. However, the self-reported ratio of actual streptokinase:tPA use was about 3:1, and 73% indicated that the government's funding policy had limited the availability of tPA in their hospital. The respondents were almost equally divided as to whether the policy should be changed. The guidelines were deemed helpful by 85% of the noncardiologists, as opposed to 52% of the cardiologists (p less than 0.005). OMA involvement in developing and circulating such guidelines was supported by 74% of the respondents and opposed by 18%; opposition was more likely to come from those who found the guidelines unhelpful (p less than 0.001). Support for involvement by the College of Physicians and Surgeons of Ontario was much weaker (supported by 32%, opposed by 62%). Overwhelming opposition to government involvement was evident.

A simple model was developed to project the potential effect of intravenous thrombolytic therapy on the caseloads of revascularization early after acute myocardial infarction. Published data were used to estimate the proportion of infarct patients eligible for thrombolytic treatment and their subsequent rates of percutaneous transluminal coronary angioplasty (PTCA) or coronary artery bypass surgery (CABS) within 2 weeks and up to 6 to 12 weeks after treatment. Toronto regional caseload data were obtained from registries and hospital discharge records. Our primary projections, based only on coronary angiography for evidence of spontaneous or exercise-induced ischemia, suggest a 165% increase in the post-thrombolysis use of PTCA within 2 weeks of infarction and even greater increases 6 to 12 weeks after infarction. Adding in selective use of salvage PTCA for some patients with persisting pain despite thrombolysis increases the overall PTCA caseload within 2 weeks by 242%. Data on the current caseload of post-thrombolysis CABS are unavailable. However, our projected caseload for the 30% of infarct patients treated with thrombolytic drugs equals or exceeds the current number of CABS procedures performed on all infarct patients within a month of the event. All these projections are conservative, in that they consider neither procedures 3 to 12 months after infarction nor restenosis after PTCA. This analysis illustrates that current approaches to revascularization after thrombolytic therapy could have a substantial effect on PTCA and CABS caseloads. Further studies with improved caseload data are needed to validate these preliminary projections.

A consensus group convened under the auspices of the Ontario Medical Association produced guidelines for the use of intravenous thrombolytic agents in acute myocardial infarction. The guidelines, updated to December 1988, include the following points. 1) Any hospital that routinely accepts the responsibility for looking after patients with acute myocardial infarction could offer thrombolytic therapy if monitoring facilities are available and if the staff are experienced in the treatment of cardiac rhythm disturbances. 2) Before treatment, all patients must be carefully screened for factors predisposing to hemorrhagic complications. 3) A physician should be clearly designated as responsible for the care of the patient receiving an infusion and be available in the event of problems. 4) For the two approved agents the usual dosages are as follows: streptokinase, 1.5 million units given over 1 hour; and tissue-type plasminogen activator (tPA), 100 mg over 3 hours, delivered as 60 mg in the first hour (of which 6 to 7 mg should be given as a bolus in the first 1 to 2 minutes) and then an infusion of 20 mg/h over the next 2 hours. 5) Intravenous thrombolytics should be considered for any patient with presumed acute myocardial infarction, as suggested by prolonged chest pain or other appropriate symptoms and typical electrocardiographic changes. Expeditious treatment is critical, since myocardial necrosis occurs within hours. 6) Emergency angiography is indicated for patients with hemodynamic compromise and no apparent response to streptokinase or tPA and in those with recurrent chest pain suggestive of acute myocardial infarction despite an apparent response to intravenous thrombolysis. Angiography before discharge is recommended for patients with postinfarction angina or evidence from noninvasive testing of significant residual ischemic risk. 7) There is insufficient evidence to choose between streptokinase and tPA on the basis of the two most important outcome measures: patient survival and myocardial preservation. More conclusive evidence comparing tPA, streptokinase and another promising agent, acylated plasminogen-streptokinase activator complex, will be available in 1989-90.