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To determine it Holter monitoring can predict cardiac risk in patients when the exercise test is nondiagnostic, a total of 90 eligible patients were monitored for 24 hours after their exercise test without alterations in baseline medications. Prospective follow-up was obtained and events were confirmed by investigators unaware of subjects' clinical data. Nineteen patients (21%) had a total of 71 episodes of ST depression, all of which were asymptomatic. During a mean follow-up of 719 days, there were 10 patients with adverse events: 3 with cardiac deaths, 3 with nonfatal myocardial infarctions, and 4 with admissions for unstable angina. Of the 10 adverse events, 9 occurred in the group of 19 with ST depression detected by Holter (relative risk 34, 95% confidence interval 10 to 114). The sensitivity of ST depression was 90%, the specificity 88%, the predictive positive value 47%, and the predictive negative value 99%. In a multivariate Cox proportional-hazards model that controlled for prior history of coronary artery disease, hypercholesterolemia, and all exercise test variables, the presence of ST depression detected by Holter was the only independent predictor of outcome. In patients with nondiagnostic exercise tests, ST depression detected by Holter monitoring identified those with an increased risk of adverse cardiac events. The absence of ST depression detected by Holter was a useful predictor of low risk. (Am J Cardiol 1993;72:889-893)

One hundred thirty-four patients with redistribution on a thallium-201 exercise test who did not experience angina (group 1) were compared with 134 patients also having redistribution who had angina during the test (group 2). The groups were matched by age, sex, and peak exercise heart rate. Although patients in both groups achieved an equivalent exercise level, patients in group 1 had less frequent (53 vs 71%, p

The maximal P-wave duration in all time-aligned leads, and the maximal P-wave amplitude in leads [V.sub.5] and [V.sub.6] were measured on a 12-lead, signal-averaged electrocardiogram during the recovery period of an exercise stress test (EST). The study group consisted of 75 patients with coronary artery disease. (CAD) documented by [is greater than or equal to] 50% diameter stenosis in 1 or more arteries and a control group of 7 subjects, 15 of them young volunteers and 32 with no or minimal coronary antherosclerosis and normal left ventricular function. All subjects underwent a symptom limited EST, with use of the Ellstad protocol. Signal-averaged P waves recorded before exercise, and for the first 6 minutes in recovery were measured using a 5X magnifier. The mean P duration before exercise in the control group was 107 [+ or -] 16 ms ([+ or -] 1 standard deviation) and 111 [+ or -] 15 ms at the third minute of recovery, (p

There has been a considerable increase of interest in exercise and physical training, even for those with cardiovascular disease. The response to exercise is complex, however, and many physiological details must be considered; among these is the level of potassium in the blood, an important determinant of heart function. Since many patients with cardiovascular disease are likely to be taking beta blocker drugs, which block the beta receptors for adrenalin, the effects of exercise and training in combination with beta blockers were studied in 40 healthy volunteers. After a two-week drug-free period to establish baseline measurements, the subjects were given atenolol, propranolol, or placebo. The subjects performed maximal treadmill tests in combination with oxygen consumption measurement. The results indicated that the subjects treated with either atenolol or propranolol experienced significantly higher levels of potassium in their blood after maximal exercise than did the subjects who received only placebo. One week after the discontinuation of the drugs, the treated group returned to normal levels of postexercise potassium. The results suggest that exercise should be carefully considered for patients taking beta blocking drugs. Those with low values of serum potassium may benefit, while patients with kidney problems and a tendency towards hyperkalemia (excessive potassium) may not. The level of potassium in the bloodstream is important because relatively small changes in the potassium of body fluids outside of cells results in a large change in the voltage potential across the membrane of the cells. The effect of a small potassium change on an excitable cell like a heart muscle cell may be very serious. (Consumer Summary produced by Reliance Medical Information, Inc.)

The ability to predict who will survive an acute myocardial infarction (heart attack, AMI) is important for decision-making during treatment. Cycle length variability (CLV) measures changes in the cycles, or recurrent patterns, of a patient's electrocardiogram over a 24-hour period. In combination with results from exercise tests, CLV has been a good predictor of survival after an AMI. A decreased CLV, that is, a more uniform cycle length, is associated with increased mortality. One problem with this measure, however, is that CLV may only reflect the activity level of the patient, indicating less variability for more inactive, sicker patients. As such, it would not be a truly independent measure of physiological function. Nor is it known whether CLV alone, without the inclusion of exercise scores, can reliably predict mortality. To address these issues, electrocardiographic readings were obtained from over 800 AMI patients just before discharge from the hospital. Results from treadmill tests were also available. The patients were then followed for an average of 31 months to determine mortality. For patients who did not take the exercise test, death was much more frequent in the low-CLV patient group (54 percent) than the high-CLV group (3.5 percent). These differences could not be attributed to variation in activity level. For patients with all levels of exercise scores, CLV alone proved a good predictor of mortality. This measure may even be a better predictor than exercise alone, since it is independent of the level of training a patient might have reached. As such, CLV is a true measure of a physiological characteristic. Understanding the nature of that characteristic is necessary for the most appropriate application of CLV in treating AMI. (Consumer Summary produced by Reliance Medical Information, Inc.)

Results From [is greater than] 6,000 Consecutive Referred Male Patients Objective: To report the prevalence of abnormal treadmill test responses and their association with mortality in a large consecutive series [...]

Study objective: To assess the long-term prognostic value of dobutamine stress echocardiography (DSE) for cardiac events (cardiac death, myocardial infarction, and late revascularization) in patients with atrial fibrillation (AF). Methods: [...]