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Background/Introduction Obesity and atrial fibrillation (AF) coexist and share multiple cardiovascular risk factors. Lifestyle modifications can reduce AF burden in obese patients. However, the time invested in pursing lifestyle changes may delay AF ablation, which could negate the procedural benefit. Purpose To examine the effects of lifestyle modifications and the timing of catheter ablation on morbidly obese patients with AF. Methods This retrospective study included 217 consecutive AF patients with a body mass index (BMI) ≥35 kg/m2 undergoing AF ablation at a tertiary care center from 2012 to 2019. Modifiable risks were examined, including the time from AF diagnosis to ablation, fluctuation of BMI >5% or an increase in BMI >3% prior to ablation, mean systolic blood pressure >130 mmHg or diastolic blood pressure >80 mmHg, obstructive sleep apnea with CPAP noncompliance, hyperlipidemia without statin therapy, tobacco use, excessive alcohol use, and diabetes mellitus with hemoglobin A1c (HbA1c) ≥6.5%. The primary outcome was a composite of recurrent atrial arrhythmias and cardiovascular (CV) hospitalizations following AF ablation. A multivariate analysis adjusting for age, gender and modifiable risks was performed. Results The mean age was 61±9 years old, 58% were female and 45% had persistent AF. A substantial portion of the study patients had modifiable risk factors, ranging from 2.7% with excessive alcohol use to 67.3% experiencing delayed AF ablation, Figure 1. The median time from diagnosed AF to ablation was 1.3 years. During a mean follow-up of 2.9 years after AF ablation, 136 (62.7%) patients met the primary outcome. Only HbA1c ≥6.5% was an independent risk factor with adjusted hazard ratio of 1.57, 95% confidence interval 1.02–2.36, P=0.0412, Figure 2A. Delayed AF ablation did not alter the outcome, Figure 2B. There was no interaction between time of ablation and HbA1c ≥6.5% (P=0.67). Conclusion Substantial portions of morbidly obese patients undergoing AF ablation have potentially modifiable risk factors. Poor glycemic control with HbA1c ≥6.5% predicts an increased risk of recurrent atrial arrhythmias and CV hospitalizations, while delayed AF ablation does not. This finding underscores an importance of optimizing HbA1c in morbidly obese patients with AF to reduce adverse outcomes after ablation. Funding Acknowledgement Type of funding sources: None.

Funding Acknowledgements Type of funding sources: None. Introduction Obesity and extreme obesity increase risk of recurrent atrial fibrillation (AF) and perioperative complications following AF ablation. However, long-term outcomes following AF ablation among obese patients is unknown. Purpose To examine long-term cardiovascular (CV) mortality and hospitalization among obese patients undergoing AF ablation Methods This retrospective study included 830 consecutive patients undergoing AF ablation from January 2013 to June 2019 at a tertiary referral medical center. Patients with obesity defined as body mass index (BMI) ≥30-39.9 kg/m2 and a subgroup of patients with extreme obesity with BMI ≥40 kg/m2 were identified. Patients were monitored for mortality and hospitalization during a median follow-up time of 819 days. Multivariate model adjusting for CHA2DS2-VASc score and history of obstructive sleep apnea (OSA) was performed. Results Mean age was 62 ± 10 years and 67.5% were male. Obese patients (n = 493, 59%) had a higher CHA2DS2-VASc score, and greater prevalence of OSA. These patients tended to have higher all-cause mortality and hospitalization (adjusted HR, 1.21 95% CI 0.98 to 1.51; P = 0.078), as well as greater non-CV outcomes (adjusted HR 1.45, 95% CI 1.02 to 2.08; P = 0.04). However, CV death and admission were comparable among patients with and without obesity (adjusted HR 1.14, 95% CI 0.90 to 1.45; P = 0.28). A subgroup of 111 (13.4%) extremely obese patients were identified. In comparison with obese patients with BMI ≥30-39.9 kg/m2, patients with extreme obesity with BMI ≥40 kg/m2 had similar CV (adjusted HR 1.07, 95% CI 0.75 to 1.50; P = 0.70) and non-CV adverse outcomes (adjusted HR 1.11, 95% CI 0.69 to 1.72; P = 0.65), Figure. Conclusions Obesity is not associated with increased CV mortality or admission following AF ablation. Non-CV events are the major cause of adverse outcomes among obese patients. Identification and reversal, where possible, of non-CV comorbidity may result in improved long-term outcomes following AF ablation. In addition, extremely obese patients with BMI≥40 kg/m2 pose a similar risk of having adverse outcomes to obese patients with BMI≥30-39.9 kg/m2. Thus, patients with extreme obesity should not be excluded from catheter ablation as a management option of AF based solely on their BMI. Abstract Figure. Cumulative-Incidence Curves

Background In the era of precision medicine, it is critical for health communication efforts to prioritize personal health record (PHR) adoption. Objective The objective of this study was to describe the characteristics of patients with heart disease that choose to adopt a PHR. Methods A total of 79 patients with chronic cardiovascular disease participated in this study: 48 PHR users and 31 nonusers. They completed 5 surveys related to their choice to use or not use the PHR: demographics, patient activation, medication adherence, health literacy, and computer self-efficacy (CSE). Results There was a significant difference between users and nonusers in the sociodemographic measure education (P=.04). There was no significant difference between users and nonusers in other sociodemographic measures: age (P=.20), sex (P=.35), ethnicity (P=.43), race (P=.42), and employment (P=.63). There was a significant difference between PHR users and PHR nonusers in CSE (P=.006). Conclusions In this study, we demonstrate that sociodemographic characteristics were not an important factor in patients’ use of their PHR, except for education. This study had a small sample size and may not have been large enough to detect differences between groups. Our results did demonstrate that there is a difference between PHR users and nonusers related to their CSE. This work suggests that incorporating CSE into the design of PHRs is critical. The design of patient-facing tools must take into account patients’ preferences and abilities when developing effective user-friendly health information technologies.

Objective. The purpose of this study was to determine the type of arrhythmias induced with therapeutic versus diagnostic transthoracic low-frequency ultrasound (TLFUS) transducers in the presence of intravenous microbubbles. Methods. Intravenous perfluorocarbon-exposed sonicated dextrose albumin (PESDA) microbubbles were infused or given as a bolus injection while TLFUS was applied in the standard parasternal and apical views with either a 1-MHz therapeutic ultrasound transducer or high-mechanical-index diagnostic ultrasound (1.7 MHz). Results. Significantly more ectopy was produced by the therapeutic transducer, especially at higher-intensity settings in the continuous wave mode after bolus injections of PESDA (P

Ultrafiltration (UF) is used to treat patients with diuretic-resistant acute decompensated heart failure. The aim of this study was to identify predictors and the effect of worsening renal failure (WRF) on mortality in patients treated with UF.Based on changes in serum creatinine, 99 patients treated with UF were divided into WRF and control groups. Overall creatinine increased from 1.9 ± 9.7 to 2.2 ± 2.0 mg/dL (P.001), and WRF developed in 41% of the subjects. The peak UF rate was higher in the WRF group in univariate analysis (174 ± 45 vs 144 ± 42 mL/h; P = .03). Based on multivariate analysis, aldosterone antagonist treatment (odds ratio [OR] 3.38, 95% confidence interval [CI] 1.17-13.46, P = .04), heart rate ≤65 beats/min (OR 6.03, 95% CI 1.48-48.42; P = .03), and E/E' ≥15 (OR 3.78, 95% CI 1.26-17.55; P = .04) at hospital admission were associated with WRF. Patients with baseline glomerular filtration rate (GFR) ≤60 mg/dL who developed WRF during UF had a 75% 1-year mortality rate.WRF occurred frequently during UF. Increased LV filling pressures, lower heart rate, and treatment with aldosterone antagonist at hospital admission can identify patients at increased risk for WRF. Patients with baseline GFR ≤60 mg/dL and WRF during UF have an extremely high 1-year mortality rate.

Cardiac transplantation has become the standard modality of treatment for selected patients with end-stage heart disease who are not candidates for alternative surgical procedure and who remain symptomatic in spite of maximal medical treatment. The majority of patients undergo cardiac transplantation because of refractory heart failure. Patients considered for cardiac transplantation typically have New York Heart Association (NYHA) functional Class IV congestive heart failure and an anticipated survival of less than 1 year without cardiac transplantation.1,2 While life-threatening ventricular arrhythmias are present in the majority of patients with end-stage cardiac disease and may contribute to their poor prognosis,3–5 arrhythmias are rarely the sole reason for transplantation. The exact number of patients who have undergone cardiac transplantation with the primary indication for the procedure being refractory ventricular arrhythmias is unknown. No data have been collected in this regard by either the Registry of the International Society for Heart and Lung Transplantation or by the United Network for Organ Sharing (UNOS). It has, however, been estimated by UNOS that less than 1% of the total cardiac transplants in adult recipients may have been performed because of refractory ventricular arrhythmias.6 In our own experience (over a 13-year period with almost 400 cardiac transplants) only three patients have been transplanted because of inability to control life-threatening arrhythmias in the absence of end-stage heart failure. According to the guidelines established at the Bethesda Conference on Cardiac Transplantation,1 which have been adopted by UNOS,6 patients with refractory ventricular arrhythmias and no symptoms of congestive heart failure should be considered for cardiac transplantation only in the event of either

In programming the implantable cardioverter defibrillator (ICD), the ventricular tachycardia (VT) detection cycle length (CL) is based on the CL of the documented tachycardia but the ventricular fibrillation (VF) detection CL is set arbitrarily. Appropriate programming of VF detection may not only reduce the incidence of inappropriate ICD shocks for non-VF rhythms but can also avoid the fatal underdetection of VF. The mean VFCL may provide a useful parameter for optimal ICD programming for VF detection if it is reproducible. This study examined the intrapatient reproducibility and interpatient variation of the mean VFCL in 30 ICD patients (25 men and 5 women, mean age 63 +/- 13 years). A total of 210 VF episodes (7 +/- 4 per patient, range 3-17) induced by T-wave shocks (166) or AC (44) at the ICD implant (30 patients) and the predischarge test (12 of 30 patients) were analyzed. The mean VFCL was calculated from the stored V-V intervals in the ICDs. Although the mean VFCL varied significantly from 171 +/- 6 to 263 +/- 11 ms (P0.01) among different patients, it was reproducible among different VF episodes in an individual patient (maximal variation 4-50 ms, P0.05). The mean VFCL was not significantly different between patients with and without antiarrhythmic drugs (210 +/- 32 vs 210 +/- 23 ms, P0.05) and was correlated with the ventricular effective refractory period (r = 0.5, P0.05). The mean VFCL varies greatly among different patients but remains reproducible in an individual patient, suggesting that the mean VFCL may serve as a reference for ICD programming of VF detection.

AF is the most common sustained cardiac arrhythmia. Recognition and appropriate management of AF is important to optimize care of concurrent medical problems and prevent long-term consequences. DC cardioversion under sedation should be performed in patients with pulmonary edema, angina, or hypotension. Ventricular rate control is the first choice in stable patients with rapid ventricular rate. Anticoagulation should be considered in all patients with AF duration48 hours, except for those under 65 years old and having no other risk factors of stroke. Recent data imply that early attempts at cardioversion may increase success rates and decrease AF recurrence rates. Thus, transesophageal echocardiogram-guided early cardioversion may become more widely used.

Coronary artery disease is the underlying etiology of left ventricular dysfunction and arrhythmias in most patients who receive implantable cardioverter defibrillators (ICDs). The aim of this study was to assess the safety and feasibility of dobutamine stress echocardiography (DSE) in patients with an ICD. DSE (dobutamine up to 50 μg/kg/min, atropine up to 2 mg) was performed in 87 patients with an ICD and known or suspected coronary artery disease. The ICD was inactivated before the stress test and reactivated after the study; no serious complications occured. DSE is a safe and feasible method for evaluating myocardial ischemia in patients with an ICD.

With the increasing flexibility allowed by implantable cardioverter defibrillators that use tiered therapy, it is important to match the therapy with the arrhythmia. In this article we present scatter diagram analysis, a new computationally efficient two-channel algorithm for distinguishing monomorphic ventricular tachycardia (VT) from polymorphic ventricular tachycardia and ventricular fibrillation (VF). Scatter diagram analysis plots the amplitude from one channel versus the amplitude from another channel on a graph with a 15 x 15 grid. The fraction (percentage) of the 225 grid blocks occupied by at least one sample point is then determined. We found that monomorphic VT traces nearly the same path in space and occupies a smaller percentage of the graph than a nonregular rhythm such as polymorphic VT or VF. Scatter diagram analysis was tested on 27 patients undergoing intraoperative implantable cardioverter defibrillator testing. Passages of 4.096 seconds were obtained from rate (bipolar epicardial) and morphology (patch) leads, and digitized at 125 Hz. Scatter diagram analysis distinguished 13 episodes of monomorphic VT (28.6% +/- 4.0%) from 27 episodes of polymorphic VT or VF (48.0% +/- 8.2%) with P < 0.0005. There was overlap in only one monomorphic VT episode and one polymorphic VT or VF episode.

Vasovagal syncope is the most common cause of syncope, but its risk for driving remains uncertain. We analyzed the clinical characteristics of patients who had syncope during driving and subsequently underwent the head-up tilt test (HUTT). Of the 245 consecutive patients undergoing HUTT, 23 (9%) hador =1 episode of syncope during driving. HUTT was positive in 19 (group A) and negative in 4 (group B) patients. No patient had structural heart disease. In group A, the driving incident occurred on the first syncope in 3 patients, and the other 16 patients had 1 to 4 episodes of prior syncope not associated with driving. In group B, the driving incident occurred on the first syncope in 1 patient, and the other 3 patients had prior syncope (3 episodes in each) not associated with driving. Seven group A and 1 group B patients had 2 syncope-related driving incidents, and the remaining patients had only 1 syncope-related driving incident. The syncope-related driving incidents caused personal injury in 7 group A and 2 group B patients. One incident in 1 group A patient caused the death of another driver. After HUTT, all but 1 patient in group A received medical treatment and only 1 patient in group B received empirical beta-blocker therapy. During the follow-up of 51+/-26 months, 1 patient died and another was lost to follow-up. Of the remaining patients, 4 patients had recurrence of syncope and 2 patients had presyncope in group A. One of these patients had another syncope-related driving incident. No group B patient had syncope recurrence. A second etiology of syncope was never found in any patient. We conclude that vasovagal syncope during driving is not uncommon in patients referred for syncope evaluation. Early medical attention to patients with vasovagal syncope may help reduce syncope-related driving incidents.

We compared signal-averaged electrocardiography with invasive electrophysiological study in patients after surgical repair of congenital heart disease to determine if potentially useful correlations exist between the two methods for assessment of risk for ventricular tachycardia. Thirty-one patients (age, 1-49 years; mean, 10.6 years) with congenital heart disease repaired with right ventriculotomy or postrepair right bundle branch block (77% postoperative tetralogy of Fallot) who had electrophysiological study were studied with signal-averaged electrocardiography. Patients were classified by electrophysiological study results as having no inducible ventricular tachycardia, nonsustained ventricular tachycardia, or sustained ventricular tachycardia. Signal-averaged electrocardiograms were examined for the duration of low-amplitude (less than or equal to 40 microV) QRS signal, duration of total QRS, and root-mean-square voltage of the terminal 40 msec of the QRS. Low-amplitude terminal root-mean-square voltage of 100 microV or less had 91% sensitivity and 70% specificity for ventricular tachycardia inducible by electrophysiological study. Similar sensitivity but less specificity were seen using the criterion of 20 msec or more total low-amplitude QRS signal (initial plus terminal) or using total QRS duration of 128 msec or more. There was a weaker association between terminal low-amplitude QRS signal of 15 msec or more and inducible ventricular tachycardia.(ABSTRACT TRUNCATED AT 250 WORDS)

Infection and implantable cardioverter-defibrillator shocks are important contributing factors to discontinuation of cardioverter-defibrillator therapy in non-terminally ill patients. These patients are at a high risk of sudden cardiac death despite continued antiarrhythmic drug therapy.

Background: We conducted a study of chronic therapy with flecainide versus placebo in a small group of LQT-3 patients with the ΔKPQ deletion to evaluate the safety and efficacy of flecainide in this genetic disorder. In vitro studies have shown that flecainide provides correction of the impaired inactivation associated with the ΔKPQ deletion. Methods: A randomized, double-blind, placebo-controlled clinical trial was conducted with flecainide and placebo in six male LQT-3 subjects with the ΔKPQ deletion. Results: The lowest possible dose of flecainide associated with at least a 40 ms reduction in the QTc interval was determined in an initial open-label, dose-ranging investigation using one-fourth or half of the recommended maximal antiarrhythmic flecainide dose. QTc reduction was achieved with a flecainide dose of 1.5 mg/kg per day in 4 subjects and with 3.0 mg/kg per day in 2 subjects. Subjects were randomized to four 6-month alternating periods of flecainide and placebo therapy based on the open-label dose findings. Average QTc values during placebo and flecainide therapies were 534 ms and 503 ms, respectively, with an adjusted reduction in QTc of −27.1 ms (95% confidence interval: −36.8 ms to −17.4 ms; P < 0.001) at a mean flecainide blood level of 0.11 ±0.05 μg/ml. Minimal prolongation in QRS occurred (mean: +2.5 ms), and there were no major adverse cardiac effects. Conclusions: Chronic low-dose flecainide significantly shortens the QTc interval in LQT-3 subjects with the ΔKPQ mutation. No major adverse drug effects were observed with flecainide during this trial, but the sample size is not large enough to evaluate the safety of flecainide therapy in patients with this mutation.

In conclusion, this study demonstrates a very high diagnostic sensitivity of troponin T versus CK in the detection of minor myocardial injury after PTCA.

Background: The Long QT Syndrome (LQTS) is a genetic channelopathy with life-threatening implications. The LQT3 form of this disease is caused by mutations of the SCN5A sodium-channel gene. A specific mutation, SCN5A:ΔKPQ, is associated with repetitive reopenings of the sodium channel and prolonged inward current. This dominant inward current is manifest on the electrocardiogram as QT prolongation. Flecainide is a potent blocker of the open sodium channel. Methods and Results: The effect of flecainide on the duration of the QT-interval and the T-wave morphology was systematically evaluated in five male patients age 2–64 years having the SCN5A:ΔKPQ mutation. After baseline electrocardiograms were obtained, low-dose oral flecainide was administered for 48 hours. Serial electrocardiograms and blood flecainide levels were obtained during flecainide therapy. The QTc interval decreased on average by 104 ms, from a baseline value of 565 ± 60 ms to 461 ± 23 ms (P < 0.04) at a mean flecainide level of 0.28 ± 0.08 mg/L, with shortening of the QTonset interval (P < 0.003) and normalization of T-wave morphology. The effects of flecainide were compared with oral mexiletine in two patients, with flecainide showing greater QTc shortening and more complete normalization of repolarization. No adverse side effects or proarrhythmia were observed with flecainide in this study. Conclusion: Low-dose, oral flecainide consistently shortened the QTc interval and normalized the repolarization T-wave pattern in five LQT3 patients with SCN5A:ΔKPQ mutation. This preliminary study indicates that low-dose flecainide is a promising therapeutic agent for LQTS patients with the SCN5A:ΔKPQ sodium channel mutation. A.N.E. 2001;6(2):153–158

We repeated direct-current cardioversion of atrial fibrillation after ibutilide injection in patients who failed conventional cardioversion. Eleven of 12 patients (92%) had successful cardioversion and avoided the need for internal cardioversion.

We report a case of a patient who presented with sudden cardiac death secondary to a subtotal occlusion of a small non-dominant right coronary system. Catheterization several weeks following the initial episode revealed persistent severe right ventricular dysfunction with moderate hemodynamic compensation. Continued unstable arrhythmogenic potential at this point led to placement of an AICD device. The case highlights the potential hazard and often complacency involved in dealing with benign appearing lesions as this one. © 1995 Wiley-Liss, Inc.

The desired defibrillation threshold (DFT) obtained during intraoperative testing of an implantable cardioverter defibrillator (ICD) should be 10 J lower than the maximal energy delivered by the ICD generator. Of the 206 patients undergoing ICD implantation since December 1986, 8 (3.9%) have had initial DFTs with less than the 10-J safety margin using the standard large patch-large patch configuration. Patches were implanted by left thoracotomy in 6 and sternotomy in 1, and 1 had implantation of a transvenous defibrillation lead and subcutaneous patch. Of note, 6 (75%) of the 8 patients with high DFTs had prior open heart operations, half were on a regimen of long-term amiodarone therapy, and the mean left ventricular mass index was quite large but not significantly greater than that of patients with low DFTs. Multiple techniques was tried to improve the DFTs in this group. Satisfactory DFTs were eventually obtained in 7 (88%); the threshold was lowered from a mean of 41.4 +/- 3.8 J to 26.9 +/- 8.8 J (p = 0.002). The most effective techniques were addition of a superior vena cava lead attached by a Y connector to one of the large patch leads in some patients and conversion to a biphasic-waveform generator in 2 others. Adding a third epicardial lead did not lower the DFTs. There were no major postoperative complications or deaths attributable to these supplemental procedures. Using these techniques, satisfactory DFTs were obtained in almost all patients with an ICD.(ABSTRACT TRUNCATED AT 250 WORDS)

Background: The treatment of life-threatening arrhythmias with amiodarone or an implantable cardioverter/ defibrillator prolongs patient survival but with significant comorbidity. Previous studies have shown diminished health status and increased psychologic distress and inferred a diminished quality of life; however, a multidimensional analysis of quality of life, including patient perception, has not been performed. Methods: One hundred four consecutive patients were surveyed regarding patient demographics, health status, psychologic distress, and patient-perceived quality of life. The patients were treated with amiodarone (n=30) with an implantable cardioverter/defibrillator (n=45) and the remainder were reference patients (n=29). Results: This study confirms that patients who survive life-threatening arrhythmias have diminished health status and increased psychologic distress; however, patient-perceived quality of life is preserved. These patients report a better perceived quality of life (as measured by the Quality of Life Index) than the reference group (22.3±4.0 vs 20.5±4.4,P Conclusions: Patient-perceived quality of life is maintained in patients who survive life-threatening arrhythmias despite their diminished health status and increased psychologic distress. Measured quality of life is independent of treatment modality. Thus, caution must be exercised in assuming a diminished quality of life in patients who have survived a life-threatening cardiac event. (Arch Intern Med. 1995;155:2086-2091)

Signal-averaged electrocardiograms (X, Y and Z leads) were acquired from 24 patients with coronary artery disease and recurrent ventricular tachycardia, 24 control patients with coronary artery disease and 23 normal subjects to assess the discriminant value of fast Fourier transformation of the entire late potential period of the QRS complex. Analysis of the vector magnitude in the temporal domain (25 to 250 Hz bandpass filters) measured high frequency QRS duration, the duration of terminal signals less than 40 microV and the root mean square voltage of the last 40 ms. Late potentials were defined as terminal signals greater than 25 Hz that were less than 40 microV. Analysis in the frequency domain used a 120 ms window that encompassed (had onset with) all of the late potential, but the mean value was first subtracted to eliminate a direct current component. High frequency spectral areas (60 to 120 Hz) and the percent high frequency (100 x [60 to 120 Hz/0 to 120 Hz]) were calculated. Results in both temporal and frequency domains were similar in control patients with coronary artery disease and normal subjects. Patients with ventricular tachycardia had a longer high frequency QRS complex (p less than 0.0001) and longer high frequency terminal signals less than 40 microV (p less than 0.0004), but not significantly lower voltage in the last 40 ms. The most useful temporal domain measurement was high frequency QRS duration (if greater than or equal to 120 ms, odds ratio = 8.2). Patients with ventricular tachycardia had increased high frequency spectral areas (p less than 0.0002) in the late potential, and the percent high frequency was especially increased (p = 0.0000; if percent high frequency greater than 3.1%, odds ratio = 18.4). The odds ratio and the area under the receiver operating characteristic curve were both greater for percent high frequency than for high frequency QRS duration (p less than 0.03). All patients with ventricular tachycardia had a high frequency QRS complex greater than or equal to 107 ms or percent high frequency greater than or equal to 3.1% (sensitivity 100%). For a high frequency QRS complex greater than or equal to 107 ms and percent high frequency greater than or equal to 3.1%, specificity was 96%. Therefore, high frequencies in late potentials, not their duration or reduced voltage, most usefully identify patients with coronary artery disease who are prone to ventricular tachycardia.

ObjectivesWe sought to assess the relation between myocardial ischemia during stress echocardiography and major events in patients with implantable cardioverter-defibrillator (ICD).BackgroundThe association of myocardial ischemia with subsequent ICD therapy and mortality is unknown.MethodsWe studied 90 patients (age 65 ± 13 years, 27 women) with history of coronary heart disease who received ICD for primary (53 patients) or secondary (37 patients) prevention of sudden cardiac death. Sixty-five (72%) patients had a previous coronary artery bypass surgery. Patients underwent exercise treadmill or dobutamine stress echocardiography. Ischemia was defined as new or worsening wall motion abnormalities. End points were death and appropriate ICD therapy.ResultsMean ejection fraction was 34 ± 12%. During a mean follow-up of 2.8 ± 1.5 years, 5 patients died and 19 patients had ICD therapy. Ischemia was detected in 20 of 24 patients with subsequent events and in 24 of 66 patients without (83% vs. 36%, p < 0.001). Events occurred in 17 of the 32 patients (53%) with both ischemia and inducible ventricular tachycardia (VT) on electrophysiologic (EP) studies. None of the 16 patients without ischemia or inducible VT on EP studies had events. In a Cox multivariate analysis model, independent predictors of events were a history of spontaneous sustained VT (hazard ratio [HR] 1.9, 95% confidence interval [CI] 1.3 to 3.8), inducible VT on EP studies (HR 1.7, 95% CI 1.2 to 4.5), and ischemia (HR 2.1, 95% CI 1.2 to 3.5).ConclusionsIschemia during stress echocardiography is an independent predictor of death and ICD therapy in patients with coronary heart disease at high risk of arrhythmic death. Patients without inducible ischemia or VT on a previous EP study have a very low risk of events. A combination of ischemia and a positive EP study is associated with a very high risk of events.

The effects of amiodarone on the pharmacokinetic and electrophysiologic properties of procainamide were examined in eight patients treated for recurrent ventricular arrhythmias who received intravenous procainamide, 6 to 15 mg/kg, at control and after 1 to 2 weeks of oral amiodarone treatment. Compared with control, procainamide plasma clearance decreased from 0.43 +/- 0.12 L/kg-hr to 0.33 +/- 0.12 L/kg-hr (P less than 0.01), plasma elimination half-life increased from 3.77 +/- 0.64 hours to 5.21 +/- 0.42 hours (P less than 0.01), and volume of distribution was unchanged from 2.31 +/- 0.74 L/kg to 2.47 +/- 0.90 L/kg during amiodarone treatment. As single agents, intravenous procainamide and oral amiodarone produced equivalent increases in QRS duration, rate-corrected QT interval, right ventricular effective refractory period, and cycle length of induced ventricular tachycardia. After the addition of intravenous procainamide to amiodarone the QRS duration, rate-corrected QT interval, and, in six of eight patients, ventricular tachycardia cycle length were significantly increased compared with control or either drug alone, suggesting additive electrophysiologic effect. However, acceleration of induced ventricular tachycardia occurred in one patient with combined treatment, suggesting a potential for adverse electrophysiologic interactions. These findings indicate that amiodarone has pharmacokinetic and electrophysiologic interactions with procainamide and suggest that the intravenous dose of procainamide be reduced by 20% to 30% during concurrent drug administration.

The signal-averaged QRS complex that is prolonged because of low amplitude late potentials predicts ventricular tachycardia. This study investigated if signal-averaged low amplitude atrial potentials predict atrial fibrillation or flutter (AFF). Low amplitude potentials were considered to be high-frequency, high amplitude P (HiFP) duration recorded between 50 and 250 Hz at 1.0 mm/microV amplitude minus unfiltered P (UnFP) duration at 0.1 mm/microV. In nine normals, HiFP averaged 115.6 msec +/- 9.8 SD. HiFP were wider in 26 control patients (133.5 msec +/- 15.7, p less than 0.005) but HiFP-UnFP (11.2 msec +/- 8.5) and signals less than 10 microV terminating HiFP inscription (21.7 msec +/- 23.4) were similar to normal values. Seventeen patients with paroxysmal or recently cardioverted AFF did not have significantly longer intervals than controls (HiFP averaged 138.8 msec +/- 23.0, HiFP-UnFP 13.2 msec +/- 9.3, and signals less than 10 microV 32.4 msec +/- 19.5). Therefore, signal-averaged P waves do not identify patients with AFF.

M-mode echocardiography in a 3-year-old patient with suspected pericardial effusion was negative for the presence of an effusion. A subsequent 2-dimensional echocardiogram demonstrated a large effusion lateral to the right atrium and right ventricle. The reasons for the false-negative M-mode echocardiogram and a discussion of the literature are presented.