Antiarrhythmic drug therapy in survivors of prehospital cardiac arrest: comparison of effects on chronic ventricular arrhythmias and recurrent cardiac arrest

Assessment, significance and mechanism of ventricular electrical instability after myocardial infarction

The mechanism of reentrant tachycardia was established nearly a century ago, but the relationships between myocardial infarction and predisposition to sudden death were not unravelled until much later. In the latter half of the twentieth century many studies sought to ascertain what variables were predictive of death following myocardial infarction. Approximately one half of all deaths during the year following myocardial infarction are sudden and due to ventricular tachycardia (VT) or ventricular fibrillation (VF). We aimed to utilise non-invasive signal-averaging, along with programmed electrical stimulation of the heart, to determine whether one could predict spontaneous ventricular tachycardia and sudden death late after myocardial infarction. The sensitivity of ventricular electrical instablility (inducible ventricular tachycardia or fibrillation) as a predictor of instantaneous death or spontaneous VT was 86%, and the specificity was 83%. When other variables (delayed ventricular activation at signal-averaging, ejection fraction at gated heart pool scan, ventricular ectopic activity at ambulatory monitoring and exercise testing) were taken into account, inducible VT at electrophysiological study was the single best predictor of spontaneous VT and sudden cardiac death after myocardial infarction. The Westmead studies of Uther et al. in the decade or so from 1980 established programmed stimulation as the best predictor of sudden death after myocardial infarction. Subsequent studies by others have demonstrated a survival advantage of defibrillator implantation in patients with low ejection fraction (and inducible ventricular tachycardia) after myocardial infarction.

Drug therapy of sustained ventricular tachyarrhythmias. Is there still a role?

This article provides a review of the risks faced by patients with sustained ventricular tachycardia (VT) or ventricular fibrillation (VF) in the absence of a reversible or transient cause so that the goals of therapy can be clearly defined. The therapeutic approaches that have been proposed to achieve these goals are outlined and evidence comparing these various approaches to therapy is then summarized in order to propose an algorithm for the optimal use of antiarrhythmic drug therapies as primary therapy for selected VT/VF patients. Options for the ancillary uses of antiarrhythmic drug therapies in ICD patients are considered.

General principles of antiarrhythmic therapy for ventricular tachyarrhythmias

Sudden cardiac death due to ventricular arrhythmias is a significant cause of mortality in patients with structural heart disease. Over the past several decades, the introduction of new pharmacologic and nonpharmacologic therapy has expanded the treatment options available. This article will focus on the use of antiarrhythmic medication for the treatment of ventricular arrhythmias and will review the following: (1) treatment goals for various clinical populations, (2) the mechanisms of antiarrhythmic and proarrhythmic actions of antiarrhythmic medications, and (3) empiric versus guided pharmacologic therapy.

Efficacy and safety of procainamide in preventing arrhythmias after coronary artery bypass surgery

Arrhythmias are common after cardiac surgery and are associated with hemodynamic compromise, stroke, and prolonged hospitalization. Beta blockers prevent atrial fibrillation postoperatively, but there are few data regarding the prophylactic use of type 1 antiarrhythmic agents or the prevention of ventricular arrhythmias. Accordingly, we performed a randomized, double-blind, placebo-controlled study of the effects of oral procainamide on 100 patients undergoing elective coronary artery bypass surgery. Procainamide was received for 4 days; the dosage was adjusted for body weight. Patients receiving procainamide had a significant reduction in atrial fibrillation (16 vs 29 patient-days, p < 0.05) and ventricular tachycardia (2% vs 20%, p < 0.01). However, the incidence of atrial fibrillation was not significantly reduced (38% vas 26%). In the group achieving therapeutic serum procainamide levels, there was reduction in all measured postoperative arrhythmias. No serious cardiac or noncardiac adverse events were noted during procainamide therapy, although there was a significant increase in the incidence of nausea. We conclude that procainamide reduces arrhythmias in the early postoperative period after coronary artery bypass surgery, most prominently in patients who achieve therapeutic serum levels. This was associated with no serious cardiac adverse reactions.

An antiarrhythmic drug experience in 941 patients resuscitated from an initial cardiac arrest between 1970 and 1985

Survival rates and antiarrhythmic drug use were determined in 941 consecutive patients resuscitated from prehospital cardiac arrest due to ventricular fibrillation between March 7, 1970, and March 6, 1985. Of these patients, 18.7% were treated for at least a portion of the period with quinidine, 17.5% with procainamide, and 39.4% received no antiarrhythmic agent. Beta blockers were prescribed for 28.3% of the patients. Unadjusted comparisons of survival estimates showed dramatically lower survival rates for patients who received antiarrhythmic drugs independent of beta-blocker therapy and significantly improved survival for patients receiving beta-blocker therapy independent of antiarrhythmic use. Patients for whom antiarrhythmic therapy was prescribed also had more adverse baseline risk factors, whereas patients taking beta blockers had fewer such risk factors. After adjustment for these baseline risk factors, the use of antiarrhythmics was weakly (p less than 0.09) associated with worsened survival; 2-year survival for procainamide-treated patients was 30% and quinidine-treated patients 55% (p = 0.003). Beta-blocker therapy was associated with improved (p less than 0.001) survival. Thus, although neither procainamide nor quinidine appear to have had a benefit on mortality, the effect of procainamide appears to be significantly worse than that of quinidine. The use of antiarrhythmic drug therapy in patients resuscitated from prehospital ventricular fibrillation should be regarded as not only unproved, but potentially hazardous, and should probably be restricted to testing in randomized clinical trials.

The long-term prognosis of patients with out-of-hospital cardiac arrest but no inducible ventricular tachycardia

The long-term prognosis of patients successfully resuscitated from cardiac arrest who do not have acute precipitating factors and in whom ventricular arrhythmias cannot be induced during baseline electrophysiologic testing is controversial. The purpose of this investigation was to evaluate the long-term risk of recurrent sudden death and determine the clinical, angiographic, hemodynamic, and electrophysiologic predictors of recurrent cardiac arrest in such patients. Twenty-six (37%) of 71 consecutive patients with a single episode of aborted sudden death did not have inducible ventricular arrhythmias (less than 7 intraventricular responses) during baseline drug-free electrophysiologic study and they form the basis of this report. Their mean age was 54 +/- 13 (mean +/- SD) years and the left ventricular ejection fraction (LVEF) was 0.47 +/- 0.17. After a mean follow-up period of 16 months, 11 patients (42%) had a recurrent cardiac arrest (fatal in 10 patients). The actuarial incidence of recurrent cardiac arrest was 30 +/- 10% at 1 year and 55 +/- 13% at 3 years. Patients with LVEF less than or equal to 0.40 had a significantly higher occurrence of recurrent cardiac arrest than those with LVEF greater than 0.40 (p = 0.02; 1-year actuarial incidence of 57 +/- 17% versus 13 +/- 19%). Patients with recurrent sudden death had a significantly greater incidence of dilated cardiomyopathy (55% versus 7%; p = 0.02) and baseline frequent premature ventricular contractions (PVCs greater than 10/hr; 64% versus 17%, p = 0.036) or nonsustained ventricular tachycardia (36% versus 0%; p = 0.37) than patients without these characteristics.(ABSTRACT TRUNCATED AT 250 WORDS)

Prolongation of ventricular refractoriness by class Ia antiarrhythmic drugs in the prevention of ventricular tachycardia induction

The effects of class la antiarrhythmic drugs (procainamide, quinidine) on the right ventricular effective refractory period (VERP) and intraventricular conduction time were assessed during serial invasive electrophysiologic studies for sustained monomorphic ventricular tachycardia (VT). In 47 patients with remote myocardial infarction, sustained VT was inducible by up to two extrastimuli after the basic drive at one of two basic cycle lengths at the right ventricular apex. With oral drug administration, sustained VT was no longer inducible (group I) in 27 patients but remained inducible (group II) in 20 with the same protocol. Class la drugs prolonged the VERP in both groups, but there was greater lengthening when drugs were effective (e.g., +32 +/- 14 msec in group I vs +12 +/- 19 msec in group II; p less than 0.005, basic cycle length 600 to 700 msec). Prolongation of the VERP by greater than 30 msec had an 88% positive predictive value for prevention of sustained VT induction. In all except one patient in group I, drugs prolonged the VERP such that the coupling intervals that had resulted in sustained VT induction under control conditions were no longer attainable. In contrast, conduction time through the ventricle (surface QRS duration) in sinus rhythm and during right ventricular pacing was prolonged similarly regardless of efficacy (e.g., +33 +/- 21 msec vs +27 +/- 27 msec at a cycle length of 400 msec). The presence of similar plasma levels of drug did not imply equivalent prolongation of the VERP in the two groups. These results suggest that greater prolongation of the VERP by oral procainamide or quinidine correlates with drug efficacy against VT induction and is a better predictor of drug effect than achievement of a "therapeutic plasma level."

Time-dependent risk of and predictors for cardiac arrest recurrence in survivors of out-of-hospital cardiac arrest with chronic coronary artery disease

One hundred one consecutive patients with chronic coronary artery disease who had survived out-of-hospital cardiac arrest in the absence of acute myocardial infarction underwent electrophysiologic evaluation and were followed prospectively. Ventricular tachyarrhythmias were inducible in 76 patients (75%) in the control state and were suppressed by antiarrhythmic drugs or surgery in 32 of the 76 patients (42%). During a mean follow-up of 27 months, cardiac arrest recurred in 21 patients: in two of the 25 patients in whom ventricular tachyarrhythmias were not inducible in the control state, three of the 32 in whom inducible ventricular tachyarrhythmias were suppressed after treatment, and 16 of the 44 in whom inducible ventricular tachyarrhythmias could not be suppressed after treatment. Actuarial rate of cardiac arrest recurrence was 11.2% during the first 6 months of follow-up ("high-risk early phase") and then decreased to less than 4% in each subsequent 6-month period. Multivariate Cox proportional hazards analysis identified an ejection fraction less than 35% (p = 0.0013) and persistent inducibility of ventricular tachyarrhythmias (p = 0.0025) as independent predictors of cardiac arrest recurrence for the entire follow-up period. Separate analysis of variables within and after the first 6 months showed that an ejection fraction less than 35% was the strongest predictor for early phase recurrence (p = 0.0078) but had only marginally significant predictive value for late phase recurrence (p = 0.0516). Persistent inducibility of ventricular tachyarrhythmias had no significant predictive value for early phase recurrence (p = 0.1382) but was the strongest predictor for late phase recurrence (p = 0.0061). These data suggest that, in patients with chronic coronary artery disease who survive out-of-hospital cardiac arrest, poor ejection fraction and persistent inducibility of ventricular tachyarrhythmias have a different predictive influence on early and late phase recurrence. Time-dependent risk factor analysis may have great clinical relevance in assessing an individual's changing risk over time.

Sudden cardiac death: etiologies, pathogenesis, and management

Sudden death claims an estimated 350,000 lives per year in the United States. When death occurs within 1 hour of the onset of symptoms, 90% are the result of ventricular tachyarrhythmias. The majority of victims are middle-aged men with coronary artery disease, but in approximately 25%, sudden death is the presenting manifestation of their problem. In some populations, the detection of premature ventricular complexes (PVCs) by ambulatory monitoring is predictive of an increased risk of sudden death. However, the arrhythmia that best predicts this risk is unclear, and ambient arrhythmias are only a modest marker of this risk. Therapy to suppress asymptomatic PVCs has not been shown to be effective in preventing sudden death, and in some cases, lethal arrhythmias can be prevented without significant effects on ambient arrhythmias. Other risk markers such as depressed left ventricular function and the presence of low-amplitude, long-duration, late potentials recorded on a signal averaged electrocardiogram are more powerful predictors of risk than are PVCs. These latter findings in particular support the presence of areas of slow electrical conduction (a requirement for reentrant mechanism arrhythmias) and suggest that an abnormal electrical environment or "substrate" is the most important factor in this problem. The management of patients at risk for sudden death is controversial. While postinfarct survivors with arrhythmias constitute a population at increased risk, the absolute risk is only about 5% in the first year and has not been shown to be improved by conventional antiarrhythmic drugs. Small study size, arrhythmia variability, ill-defined end points, and proarrhythmia may partially explain this apparent lack of efficacy. The prophylactic use of antiarrhythmic drugs other than beta-blockers to prevent sudden death in asymptomatic populations at risk is therefore of unproven benefit. By contrast, patients who have survived a life-threatening arrhythmia unrelated to an acute myocardial infarction have an approximately 30% risk of recurrence in the following year. In these patients, the use of ambulatory monitoring to guide therapy is limited by the high incidence of false-negative responses (lethal arrhythmia recurrence despite ambient arrhythmia suppression) and the lack of frequent spontaneous arrhythmias in many patients. In this patient population, electrophysiological testing can be used to prognosticate recurrence and gain insight into arrhythmia mechanism, stability, and hemodynamic tolerance. The technique is also useful in guiding both pharmacological and nonpharmacological therapy.(ABSTRACT TRUNCATED AT 400 WORDS)

Procainamide N-acetyltransferase: modulation by clofibrate and a microsomal form

1. Detoxification of procainamide by N-acetyltransferase which occurs primarily in the cytoplasmic fraction of the rat liver can be modulated by clofibrate treatment. 2. When the concentration of one of the substrates, procainamide, is 100 microM while the other, acetyl CoA, is 10 or 100 microM, the specific activity is reduced following clofibrate treatment. However, total activity is unchanged because of a 44% increase in cytoplasmic protein. 3. At more physiological levels of the two substrates (10 microM), total enzyme activity is increased from 9.5 +/- 1.5 to 14.0 +/- 1.8 pmol/mg/min, P less than 0.05. 4. A microsomal form of N-acetyltransferase activity is reported which is unaffected by the concentration of acetyl CoA in contrast to the cytoplasmic form.

Atenolol, but not mexiletine, protects against stimulus-induced ventricular tachycardia in a chronic canine model

1. In a placebo-controlled study of the antiarrhythmic and electrophysiological properties of atenolol and mexiletine, programmed electrical stimulation (PES) was performed in three groups of six conscious greyhounds, 7-30 days after coronary artery ligation. 2. In the placebo group, repeated PES challenge resulted in the consistent induction of ventricular tachycardias (VT) in 4/6 dogs and ventricular fibrillation in 2/6. Atenolol prevented arrhythmia induction in 4/6 dogs, one continued to demonstrate a VT and one died (P less than 0.05 compared with placebo). In the mexiletine group 5/6 dogs continued to demonstrate a VT and one died. 3. Electrocardiographic parameters were not affected by any treatment. There was no change in blood pressure in any group but when compared with placebo, heart rate fell (P less than 0.05) after atenolol (256 micrograms kg-1) and increased (P less than 0.05) after mexiletine (16 mg kg-1). Effective (ERP) and functional (FRP) refractory periods did not change after mexiletine, but ERP was prolonged (P less than 0.05) after atenolol. 4. The results indicate that atenolol but not mexiletine is effective in preventing re-entrant arrhythmias in this conscious canine model. Antiarrhythmic efficacy may be related to a fall in heart rate and/or a prolongation of refractoriness.

The premise, promise, and perils of the prevention of lethal ventricular tachyarrhythmias

Sudden cardiac death caused by ventricular tachyarrhythmias claims about 360,000 lives a year in the United States. The premature ventricular complex (PVC) hypothesis has been the cornerstone for understanding this problem, but it is now recognized as an incomplete explanation for this catastrophy. The recognition of the importance of structural heart disease in this process has led to the development of the Substrate Hypothesis as an alternative explanation. In this construct, PVCs may trigger lethal arrhythmias but only if an abnormal electrophysiologic substrate is present. This hypothesis more completely describes the pathophysiology of the process, provides the basis for understanding the value and limitations of the techniques used for risk assessment and management, and helps clarify the potential endpoints and potential adverse effects of therapy to prevent arrhythmias. Since no single diagnostic technique is ideal and no therapeutic modality is universally effective, an approach to the management of this problem must be multidimensional and based on a firm understanding of the actual risk of a life threatening arrhythmia, the potential but unproven benefits and uncertain endpoints of drug therapy, the cost, and the potential for arrhythmia exacerbation or significant side effect.

Comparative bioequivalence and efficacy of two sustained-release procainamide formulations in patients with cardiac arrhythmias

This investigation evaluated the bioequivalence and efficacy of two sustained-release procainamide products. Ten patients with cardiac arrhythmias were randomized to product A (Procan-SR) or product B (Pronestyl-SR). After nine doses of study medication, plasma procainamide and N-acetylprocainamide concentrations were obtained to determine the area under the concentration versus time curve at steady state (AUCSS), mean plasma concentration (CSSav), the observed peak plasma concentration (CSSmax), the observed trough plasma concentration (CSSmin), and the apparent time to achieve CSSmax (tmax). The products were compared on a milligram-equivalent (adjusted) basis. Following completion of blood sampling, patients were crossed-over to the alternate product. There was no washout between treatments. After nine doses of the alternate test medications, blood sampling was repeated. Differences in AUCSS, CSSav, CSSmax, tmax, and intradose peak/trough ratios were not statistically significant. Within-group variability in AUCSS, CSSav CSSmax, and tmax was greater with product B, but this trend did not reach statistical significance. Antiarrhythmic efficacy was not significantly different between the two treatments. Although the greater bioequivalence, lesser variability, and the greater number of tablet dosage sizes would favor product A, patients stabilized on a particular brand of sustained-release procainamide should not be switched to another product without careful monitoring. One patient in this study developed nonsustained ventricular tachycardia with low procainamide plasma concentrations after being switched from product A to product B.

Ventricular fibrillation survivors in whom tachyarrhythmia cannot be induced: outcome related to selected therapy

Eight-five patients were studied to determine the prognosis of the ventricular tachyarrhythmias at the time of electrophysiologic study. Twenty-five patients (29%) were not inducible when we used a stimulation protocol consisting of up to four extrastimuli delivered at two right ventricular sites. Patients with no inducible arrhythmias were younger (53 vs 59 yrs; p = .06) and had higher ejection fractions (.49 vs .34; p less than .04) than the inducible ventricular fibrillation survivors. Sex, cardiac diagnosis, time from event to electrophysiologic study, and antiarrhythmic therapy at the time of event did not discriminate between those with and those without inducible ventricular tachyarrhythmias. Survival free of recurrent sudden death or ventricular tachycardia was .86 +/- .05 and .95 +/- .05 for patients with and without inducible tachyarrhythmias, respectively (p = .22). Nine of 25 (36%) patients with no inducible arrhythmias developed inducible ventricular tachyarrhythmias when testing was repeated with an antiarrhythmic drug. Ventricular fibrillation survivors not inducible at the time of programmed ventricular stimulation (using a stimulation protocol consisting of four extrastimuli delivered at two right ventricular sites) seem to have a good prognosis. Many "noninducible" patients develop inducible tachyarrhythmias when placed on antiarrhythmic therapy. Because it is possible that these drugs are proarrhythmic, empiric antiarrhythmic therapy should be avoided in these patients.

Efficacy and tolerance of tocainide during long-term treatment of malignant ventricular arrhythmias

A group of 51 patients with malignant ventricular arrhythmias refractory to standard oral antiarrhythmic agents were treated with oral tocainide. Antiarrhythmic efficacy was defined as total abolition of occurrences of ventricular tachycardia (VT) or ventricular fibrillation (VF) as assessed by hospital admissions for arrhythmias and the occurrence of sudden cardiac death (SCD). Of the 51 patients, 32 (63%) initially tolerated tocainide and were discharged from the hospital. Of the 19 patients not initially responding to tocainide, 6 (12%) had arrhythmia recurrence and 13 (25%) developed intolerable central nervous system or gastrointestinal side effects. Of these 19 short-term nonresponders, 8 (42%) patients suffered SCD over an average follow-up of 24 months (annual SCD rate of 21%). Two patients suffered SCD during the first week of tocainide therapy. Discounting the 2 patients with SCD on tocainide therapy, 6 of 17 (35%) patients initially withdrawn from tocainide suffered SCD (annual SCD rate of 18%). Twenty-four of the 32 short-term responders did not have arrhythmia recurrence over a mean follow-up of 38 months resulting in an overall long-term efficacy of 47% (24/51). Over an average follow-up of 38 months for these 24 short-term responders, 12 patients expired from nonarrhythmic causes, 3 patients were withdrawn for non-drug-related causes, and 9 patients remain on tocainide therapy. Of the 8 long-term nonresponders, 3 patients had arrhythmia recurrence and died suddenly while 5 patients developed intolerable side effects. The annual SCD rate in short-term responders was 3%. Eighteen of the 51 patients (35%) were withdrawn from the study because of adverse effects.(ABSTRACT TRUNCATED AT 250 WORDS)

Comparison of the characteristics of nonsustained ventricular tachycardia on Holter monitoring and sustained ventricular tachycardia observed spontaneously or induced by programmed stimulation

The characteristics of nonsustained ventricular tachycardias (VT) on Holter monitor recordings were compared with the characteristics of sustained VT noted spontaneously or induced by programmed stimulation in 50 patients with a history of spontaneous sustained VT. At baseline before antiarrhythmic therapy, all patients had nonsustained VT (triplets or longer) on Holter recordings and sustained VT inducible by programmed stimulation. The mean rate of the fastest nonsustained VT on Holter monitoring (150 +/- 52 beats/min) was significantly slower that that of induced sustained VT (246 +/- 56 beats/min) (p less than 0.001). Compared with nonsustained VT on Holter monitoring, sustained VT by programmed stimulation were faster in 45 of 50 patients, similar in 2 and slower in 3. There was a poor correlation between the rates of nonsustained VT and sustained VT (r = 0.2195). The duration of the longest nonsustained VT was fewer than 6 beats in 24 patients and 6 beats or more in 26. The mean rates of induced sustained VT were not significantly different between patients with shorter (fewer than 6 beats) and longer (6 or more beats) nonsustained VT. In 12 patients, the rate of spontaneous sustained VT was available. The rate of spontaneous sustained VT (217 +/- 59 beats/min) was similar to that of sustained VT by programmed stimulation (277 +/- 60 beats/min). There was a close correlation (r = 0.8036) between the rates of spontaneous and induced sustained VT. However, the rate of nonsustained VT on Holter monitoring (151 +/- 76 beats/min) was significantly slower than the rate of spontaneous sustained VT (p = 0.002).(ABSTRACT TRUNCATED AT 250 WORDS)

Ventricular arrhythmia: management strategy

The management of ventricular arrhythmia continues to be one of the most difficult therapeutic problems in medicine today. Both invasive and noninvasive techniques have demonstrated success in management of patients at high risk for sudden cardiac death. High-risk subgroups include patients who have experienced sudden cardiac death and have been resuscitated successfully, patients with high-grade ventricular ectopy associated with left ventricular dysfunction, and patients who have had recent myocardial infarction. Traditional and experimental antiarrhythmic agents are available to the clinician, and in some patients combination therapy may prove more useful than application of a single agent alone. In individuals in whom pharmacologic intervention fails, map-guided surgical excision may be beneficial. The application of the automatic implantable defibrillator appears to have promise in truly refractory situations.

Comparison of sustained-release quinidines given twice daily to patients with ventricular ectopy

To compare the steady-state kinetic profiles and ectopy-suppression rates of two sustained-release forms of quinidine with those of a conventional quinidine preparation, 18 patients with ventricular ectopy were studied in randomized crossover fashion. The drugs were conventional quinidine sulfate 300 mg q6h, sustained-release quinidine sulfate 600 mg q12h, and sustained-release quinidine gluconate 648 mg q12h. Following baseline electrocardiographic ambulatory monitoring, each drug was given for three days, with repeat ambulatory monitoring and serial plasma drug level determinations performed on the third day. There were no washout periods between treatments. Plasma quinidine levels were assayed by both enzyme multiplied immunoassay technique (EMIT) and quinidine-specific high-performance liquid chromatography (HPLC) methods. Using actual steady-state HPLC values, there were no differences in the area under the plasma concentration-time curve (AUC) among the three treatments; the dose-corrected AUC was greater for quinidine gluconate than for the other two preparations. Using EMIT values, mean plasma quinidine levels from the conventional quinidine sulfate regimen were greater during the last five hours of the 12-hour study interval. A consistently strong inverse relationship between EMIT plasma quinidine levels and hourly ectopy rates was present in only one of eight (13%) responders. Diurnal variation of quinidine kinetics was observed after two days of each treatment; trough values at midnight were slightly lower than trough values at noon. Among patients demonstrating at least 70% suppression of premature ventricular contractions (PVCs), there were no differences in ectopy rates or ectopy-suppression rates among treatments. Dosing sustained-release quinidine sulfate 600 mg or quinidine gluconate 648 mg q12h was clinically acceptable in the small number of responders studied.

Clinical electrophysiology, efficacy and safety of chronic oral cibenzoline therapy in refractory ventricular tachycardia

The electrocardiographic (ECG) and electrophysiologic (EP) effects, clinical efficacy and safety of oral cibenzoline therapy were evaluated using a twice-daily dosing regimen in patients with refractory ventricular tachycardia (VT). Twenty patients underwent EP studies in the control (drug-free) state and after cibenzoline therapy using an incremental dose-titration protocol. Oral cibenzoline (2.4 to 5.8 mg/kg/day) was administered in doses of 130, 160 or 190 mg at 12-hour intervals. ECG and EP variables, 24-hour ambulatory ECG monitoring and programmed electrical stimulation studies were obtained in the control state and after 11 +/- 4 days of cibenzoline therapy. Cibenzoline therapy prolonged the mean PR interval (from 179 +/- 29 to 201 +/- 36 ms, p less than 0.001), the mean QRS duration (from 107 +/- 21 to 130 +/- 25 ms, p less than 0.001), and the mean QTc interval (from 422 +/- 25 to 460 +/- 42 ms, p less than 0.001). It increased the mean HV interval (from 50 +/- 17 to 65 +/- 20 ms, p less than 0.01) and mean right ventricular effective refractory period (from 245 +/- 24 to 266 +/- 27 ms, p less than 0.01). After cibenzoline therapy, 5 patients (25%) had suppression of inducible sustained VT during programmed electrical stimulation. High-degree atrioventricular block occurred in 2 patients. Chronic cibenzoline therapy (mean follow-up 24 +/- 3 months) remained effective in long-term suppression of VT in 4 patients. Two patients had to discontinue therapy because of gastrointestinal intolerance. Cibenzoline is effective in suppression of refractory VT in selected patients using a twice-daily dosing schedule.

Long-term therapy with disopyramide phosphate: side effects and effectiveness

In this study, the safety and efficacy of long-term therapy with disopyramide phosphate were evaluated in 40 patients with documented, recurrent, symptomatic tachyarrhythmias. Twenty-one (53%) of the patients had organic heart disease, and nine of these patients had compensated congestive heart failure. The tachyarrhythmias which were treated were paroxysmal supraventricular tachycardia (21 patients), paroxysmal atrial fibrillation (six patients), and paroxysmal ventricular tachycardia (13 patients). In each patient there was evidence, from continuous ECG monitoring or electrophysiologic testing, that disopyramide would be effective therapy, and each patient was able to tolerate disopyramide (no side effects or tolerable side effects) during an initial trial period of 1 to 2 weeks. Dosages of disopyramide were 400 to 1600 mg/day (994 +/- 320 mm/day). During long-term therapy, side effects were reported by 28 (70%) of the patients. The side effects were usually anticholinergic, and were usually a continuation of side effects noted during the initial trial period. None of the patients had idiosyncratic reactions to disopyramide. Most of the patients found side effects to be tolerable; however, in seven patients it was necessary to discontinue disopyramide after 1 to 8 (6 +/- 3) months. Actuarial incidence of intolerable side effects was 21 +/- 7% at 12 months. Nine (22%) of the 40 patients had symptomatic recurrences of tachyarrhythmia after 3 to 32 (15 +/- 9) months of therapy. Actuarial incidence of drug ineffectiveness was 32 +/- 10% at 24 months. Disopyramide was both effective and tolerated in 24 (60%) of the patients, who were followed for 2 to 64 (23 +/- 16) months.(ABSTRACT TRUNCATED AT 250 WORDS)

Utility of ambulatory electrocardiographic monitoring for predicting recurrence of sustained ventricular tachyarrhythmias in patients receiving amiodarone

The prognostic implications of changes in ventricular ectopic activity on serial 24 hour ambulatory electrocardiographic (Holter) recordings were prospectively evaluated in 107 patients with a history of sustained ventricular tachyarrhythmias treated with amiodarone for at least 30 days. Twenty-seven patients (25%) had insufficient ventricular ectopic activity (less than 10 ventricular premature complexes/h and no repetitive forms) on baseline Holter recordings for serial statistical analysis. In 53 (66%) of the remaining 80 patients, serial 24 hour Holter monitor recordings showed efficacy of treatment, defined as a 75% decrease in ventricular premature complexes, a 95% decrease in ventricular couplets and absence of ventricular tachycardia. During a mean follow-up period of 14.2 +/- 9.9 months, 34 (32%) of the 107 patients had recurrence of a sustained ventricular tachyarrhythmia. Holter recording correctly predicted nine recurrences and correctly identified 37 patients who did not experience a recurrence. Holter efficacy failed to predict recurrence of a sustained ventricular tachyarrhythmia in 16 patients, and 18 patients remained free of recurrence despite failure to achieve Holter efficacy. The positive predictive value of Holter monitoring efficacy was 33% and the negative predictive value was 70%; however, these differences were not statistically significant by chi-square analysis. Similar results were obtained using Holter recordings performed relatively early in therapy (6 weeks and 4 months). Of the 27 patients without significant ventricular ectopic activity on the baseline Holter recording, 9 had an arrhythmia recurrence despite continued infrequent ventricular premature complexes and no repetitive forms on subsequent recordings. The recurrence rate in this group (33%) was similar to the overall recurrence rate.(ABSTRACT TRUNCATED AT 250 WORDS)

Comparison of propafenone and disopyramide for treatment of chronic ventricular arrhythmias: placebo-controlled, double-blind, randomized crossover study

In a double blind, placebo-controlled study, the efficacy of propafenone, a new antiarrhythmic drug was compared to that of disopyramide. Sixteen patients with frequent and complex premature ventricular contractions (PVCs) were studied by serial 24-hour ambulatory monitoring, while they were receiving propafenone, 300 mg, and disopyramide, 200 mg, both every 8 hours. A reduction in the mean frequency of PVCs per hour, in comparison to the placebo period, from 574 +/- 535 to 100 +/- 130, was observed after propafenone (p less than 0.005) and from 629 +/- 455 to 231 +/- 280 after disopyramide (p less than 0.008). A greater than 70% reduction in PVCs in comparison to placebo was observed in 11 of 14 after propafenone and 9 of 15 after disopyramide (NS). A greater than or equal to 90% reduction in PVCs was observed in 9 of 16 with propafenone and in 4 of 15 with disopyramide (p less than 0.05). The suppression of complex PVCs (repetitive, polymorphic, or more than 5/min with bigeminism) was observed in 11 of 14 after propafenone and in 9 of 14 after disopyramide. The abolition of nonsustained ventricular tachycardia was observed in 6 of 6 and 3 of 5, respectively, after propafenone and disopyramide (p less than 0.05). A lower incidence of side effects, 4 of 16 vs 8 of 16, was observed during propafenone than during disopyramide treatment. We conclude that propafenone, in a dose of 900 mg daily, is more effective than disopyramide, in a dose of 600 mg daily, in the treatment of frequent and complex PVCs and nonsustained ventricular tachycardias. Propafenone also showed a lower incidence of side effects.

Ventricular arrhythmias in severe heart failure: incidence, significance, and effectiveness of antiarrhythmic therapy

Forty-three patients receiving maximal medical therapy for severe chronic heart failure from dilated cardiomyopathies (28 ischemic, 15 idiopathic) and ventricular premature beats (VPBs) on the 12-lead ECG had baseline 24-hour ambulatory ECG monitoring. Complex VPBs (multiform, repetitive--couplets, R on T phenomenon) and asymptomatic, nonsustained ventricular tachycardia were present in 38 patients (88%) and 22 patients (51%), respectively. Twenty-three patients (group I) were placed on long-term antiarrhythmic therapy (20 patients received procainamide and the remaining quinidine). Twenty patients (group II) did not receive antiarrhythmic therapy. At baseline, no significant differences between the two groups were noted for age, functional class, type of cardiomyopathy, medical therapy for heart failure, cardiothoracic ratio, radionuclide ejection fraction, or rate and complexity of the ventricular arrhythmias on the 24-hour ambulatory ECG tracings. At a mean follow-up period of 16 months (range 1 to 37), there were 16 deaths, 10 (62%) of which were sudden and unexpected. No significant differences in the incidence of sudden death and overall mortality were noted between the two groups. Among patients with nonsustained ventricular tachycardia, those who died suddenly had a lower mean left ventricular ejection fraction (0.15 +/- 0.01) when compared to the survivors (0.23 +/- 0.02; p less than 0.01). It is concluded that patients with severe heart failure have a high mortality from both sudden and nonsudden cardiac death, incidence of complex VPBs is very high, sudden death is more common when the left ventricular function is severely compromised, and apparently, therapeutic plasma levels of conventional antiarrhythmic drugs do not protect this group of patients from dying.

Value of Holter monitoring in identifying risk for sustained ventricular arrhythmia recurrence on amiodarone

Seventy-four patients with sustained ventricular tachyarrhythmias had 22 +/- 3 hours of Holter monitoring before and after 11 +/- 6 days of amiodarone treatment. On control Holter recordings, 55 patients (group I) had frequent (more than 10 extrasystoles per hour) and/or complex (at least couplets) ventricular ectopic activity (VEA), and 19 patients (group II) had infrequent and simple VEA. A positive Holter monitor response to amiodarone was defined as a decrease in VEA by more than 85% and abolition of all complex VEA. In group I, 34 patients (62%) had a positive Holter monitor response. In group II, 16 patients (84%) had persistent, infrequent and simple VEA and 3 had frequent and/or complex VEA. During a mean follow-up of 13 +/- 12 months, 22 patients (30%) had ventricular tachycardia (VT) or sudden death. In group I, VT or sudden death occurred in 6 of 34 (18%) patients with a positive Holter monitor response and 11 of 21 (52%) with a negative Holter monitor response (p less than 0.01), and in group II, VT or sudden death occurred in 5 of 16 patients (31%) with persistent, infrequent and simple VEA. All episodes of VT or sudden death occurred after at least 2 weeks of amiodarone therapy (mean 5 +/- 6 months). The predictive accuracy of a positive Holter monitor response as an indicator for subsequent prevention of sustained ventricular tachyarrhythmias and sudden cardiac death was 82% and for a negative Holter monitor response as an indicator of tachyarrhythmia or sudden death recurrence on therapy it was 52%.(ABSTRACT TRUNCATED AT 250 WORDS)

The utility of aprindine blood levels in the management of ventricular arrhythmias

Sixty-four patients with a history of ventricular tachycardia and ventricular fibrillation refractory to conventional therapy received aprindine to abolish recurrent episodes of symptomatic ventricular tachycardia. Fifty-six patients became asymptomatic and were followed up for a mean period of 23 months. Aprindine dose was adjusted to minimize adverse reactions but still control arrhythmia. Survival analysis was performed for the group with aprindine levels greater than 1.5 micrograms/ml and the group with levels of 1.5 micrograms/ml or less. At the end of the study, 65% of the patients with a high level were alive and asymptomatic as compared with only 35% of the patients with a low level (p less than 0.036). In patients at risk of recurrent sudden cardiac death, high aprindine levels maintained after abolition of symptomatic ventricular tachycardia were associated with improved survival.

The role of Holter monitoring in patients with recurrent sustained ventricular tachycardia: an electrophysiologic correlation

The significance of spontaneous ventricular premature depolarization (VPD) frequency and severity in patients with sustained ventricular tachycardia undergoing serial electrophysiologic studies (EPS) are unknown. Nineteen patients with sustained ventricular tachycardia were studied with 24-hour Holter recordings prior to control EPS and prior to each drug trial. Successful drug or surgical treatment (with the exception of amiodarone) was based upon noninducibility of ventricular tachycardia in the laboratory. Among the eight noninducible and nonamiodarone medically treated patients, two (25%) had significant VPD reduction and/or Lown class improvement. The remaining six (75%) had no change or worsening of Holter findings, despite noninducibility of sustained VT. Among the six amiodarone-treated patients, five of whom were persistently inducible prior to discharge, four (66%) had improved and two (33%) had worsened Holter findings compared to control. None of the five (100%) surgically managed patients were inducible postoperatively, and three of the five (60%) had no change or worsening of Holter findings. We conclude that (1) EPS are superior to Holter findings in assessing successful management; and (2) Holter findings may be concordant or discordant during EPS serial drug trials or following surgery and therefore cannot predict the success or failure of the intervention.

Propafenone for refractory ventricular arrhythmias: correlation with drug plasma levels during long-term treatment

The efficacy of propafenone, a new antiarrhythmic drug, was studied in 21 patients with ventricular arrhythmias refractory to previous antiarrhythmic medications. Group A included 10 patients with chronic ventricular premature complexes (VPCs), 6 of whom had nonsustained ventricular tachycardia (VT) and 4 of whom had recurrent, sustained VT; all received propafenone, 900 mg/day. Group B included 11 patients, all with chronic VPCs, 9 of whom had nonsustained VT and 5 of whom had sustained VT; all received propafenone, 450 mg/day. Drug efficacy was evaluated as a 70% or greater reduction in VPC frequency with complex VPC abolition in ambulatory monitoring and suppression of nonsustained VT and sustained VT during a follow-up period up to 154 +/- 58 days in group A and 96 +/- 42 days in group B. Drug plasma levels were measured during chronic therapy in pharmacologic steady state. In group A, propafenone reduced the frequency of chronic VPCs in 9 patients and abolished nonsustained VT in 4 of 6 and sustained VT in 3 of 4; in group B, propafenone reduced the frequency of chronic VPCs in 6 patients and abolished nonsustained VT in 6 of 9 and sustained VT in 3 of 5. Two patients with recurrences of sustained VT in this group were later successfully treated with propafenone, 900 mg/day; overall, 8 of 9 patients with recurrences of sustained VT were successfully treated with 900 mg/day.(ABSTRACT TRUNCATED AT 250 WORDS)

Long-term survival after prehospital cardiac arrest: analysis of outcome during an 8 year study

We analyzed long-term follow-up data accumulated during an 8 year study of survivors of prehospital cardiac arrest. All patients included in this study were primary entrants via community-based rescue systems; patients who were tertiary referrals (survivors of cardiac arrest from other hospitals) were not included in this analysis. In the group of 61 patients entering our study between 1975 and 1980, with a follow-up to 1983, there have been a total of 24 deaths (39%). Sixteen of the 24 deaths were the result of recurrent cardiac arrest; eight were nonsudden cardiac deaths or noncardiac deaths. The mean duration from entry to death in the nonsurvivors was 27.5 +/- 19.7 months, and the time from the index event to last follow-up in the long-term survivors was 59.9 +/- 19.4 months. Life table analysis demonstrated a 10% rate of recurrence of cardiac arrest in the first year, with a 5% per year rate in each of the subsequent 3 years. Left ventricular ejection fractions at entry were not significantly different between survivors (mean = 45.3 +/- 13.6%) and nonsurvivors (mean = 37.6 +/- 12.6%), and the severity of ejection fraction abnormality at entry did not correlate with time to death in the nonsurvivors. However, ejection fraction was significantly lower in patients who died from causes other than recurrent cardiac arrest than in those who died of cardiac arrest (24.5 +/- 9.1% vs 42.7 +/- 9.2%; p less than .002).(ABSTRACT TRUNCATED AT 250 WORDS)

Value of serial electropharmacological testing in managing patients resuscitated from cardiac arrest

Electrophysiologic studies were performed in 11 patients (9 men, 2 women; mean age: 59.9 yrs) who had survived an episode of cardiac arrest due to ventricular tachycardia (VT) or ventricular fibrillation. The purpose of the studies was to evaluate the usefulness of serial acute drug testing in selecting an effective chronic antiarrhythmic regimen. Ten of the patients were suffering from chronic ischemic heart disease with one or more previous myocardial infarctions while one had no evidence of structural heart disease. A ventricular aneurysm was present in four of them. During control electrophysiologic study, a sustained VT was induced by ventricular stimulation (single and double extrastimuli at various paced ventricular cycle lengths plus bursts of rapid ventricular pacing) in nine of the ten patients (90%) who were studied while not receiving antiarrhythmic drugs; a non-sustained VT was induced in one of them (10%). In three patients (30%) VT could be initiated only by right ventricular stimulation at a side different from the apex (outflow tract). No arrhythmia was observed in the only patient who was studied while taking amiodarone orally (400 mg/day for more than three months). During serial acute drug testing a totally effective drug regimen (successful in preventing the induction of any ventricular arrhythmia) was found in seven of the ten patients (70%) who underwent this procedure and a partially effective drug regimen (a sustained VT was no longer inducible; it was easier to interrupt and it was considerably slower) was found in two patients (20%). None of the nine patients who received chronic antiarrhythmic therapy based on the results of serial acute drug testing died suddenly during a mean follow-up of 14 months (range: 3-28) and only one had a recurrence of cardiac arrest. The latter, however, was taking antiarrhythmic drugs at a dosage less than that proved to be effective during electropharmacological testing. The only patient who refused serial acute drug testing and received an empiric antiarrhythmic therapy died suddenly at the 21st month of follow-up. These results indicate that serial electropharmacological testing is useful in selecting an effective long-term drug regimen in survivors of cardiac arrest.

Evaluation of the patient with sudden cardiac death

Sudden cardiac death is defined as death from natural causes that occurs within one hour of the patient's collapse. Public education programs and the proliferation of rapidly deployable community life-support teams have resulted in the ability to deliver emergency medical care to many patients who suffer a cardiac arrest and who otherwise would have died suddenly. This article reviews the diagnostic evaluation and therapeutic management of the patient who has survived a cardiac arrest.

Lorcainide for high-frequency ventricular arrhythmia: preliminary results of a short-term double-blind and placebo-controlled crossover study and long-term follow-up

Lorcainide, 100 mg twice daily was compared with placebo in 39 patients with frequent ventricular arrhythmias in a randomized double-blind crossover trial. A mean frequency of ventricular premature beats (VPBs) of at least 30 VPBs/hour was required during a drug-free period of 48 hours. Holter monitoring and a maximal symptom-limited exercise test were performed at the end of each of the 2-week double-blind treatment phase. The group averaged 350 +/- 361 (standard deviation) VPBs/hour. Lorcainide decreased the mean VPB frequency of the group by 46% (p less than 0.01), with VPB reduction beyond the expected variation in 22 of 39 patients. In 13 patients VPBs were unchanged and in 4 they increased. Eight additional patients responded during drug titration, for an overall response rate of 77% (30 of 39). Lorcainide did not significantly reduce the exercise-related VPB frequency. At 6 months 61% of patients had significant VPB suppression. Thus, lorcainide was effective in reducing the frequency and grade of spontaneous ventricular arrhythmias during short- and long-term evaluation.

Long-term survival after prehospital sudden cardiac death

One hundred thirty-nine survivors of prehospital sudden cardiac death were followed after their hospital discharge. Eighty patients were studied with coronary angiography and cardiac catheterization; 34 of these underwent coronary bypass surgery. After a maximum follow-up of 105 months, 89 patients were still alive. The probability of survival at 6 months, 1 year, 2 years, 3 years, 4 years, and 5 years was 88%, 86%, 78%, 70%, 63%, and 59%, respectively. Of the 43 cardiac deaths, 37 (86%) were secondary to documented recurrent ventricular fibrillation or occurred suddenly. Twelve percent of the total population had recurrent ventricular fibrillation in the first year following the initial cardiac arrest, 16% within 2 years, and 22% within 3 years. Of the 37 survivors dying from recurrent ventricular fibrillation, 32% died within the first 3 months following hospital discharge, 46% in the first year, 64% within 2 years, and 78% within the first 3 years. Most survivors were capable of resuming normal activities after hospital discharge. Only 7% demonstrated permanent neurologic impairment. Sixty-eight percent of the patients who were employed at the time of their prehospital sudden cardiac arrest returned to full-time employment. In the subset of 34 surgically treated patients, there have been six (18%) cardiac deaths. Four of these deaths were related to recurrent ventricular fibrillation, with one of these deaths occurring in the immediate postoperative period. The other three deaths related to recurrent ventricular fibrillation occurred 36 months (two deaths) and 49 months following the initial prehospital cardiac arrest.

Suppression of high-grade ventricular ectopic activity by antiarrhythmic drug treatment as a marker for survival in patients with chronic coronary artery disease

In order to investigate the relationship between the ease of suppression of complex (frequent multiform, repetitive, and early) ventricular premature beats (VPBs) and subsequent survival, 50 consecutive patients with chronic coronary artery disease (CAD) were followed retrospectively during a mean observation period of 16 months. A total of 124 drug trials were performed using single or combined class I, II, and III antiarrhythmic drugs. Thirty-nine patients were considered "responders" (elimination of Lown classes greater than or equal to IVa and reduction of greater than 30 multiform VPBs to occasional unifocal VPBs during Holter monitoring), whereas in 11 patients VPBs could not be adequately suppressed ("nonresponders"). There were no significant differences in age and congestive heart failure in the two groups. There were three deaths (one sudden) in the 39 "responders" but five deaths (three sudden) in the 11 "nonresponders" (p less than 0.01 for all deaths, p less than 0.05 for sudden deaths). Cumulative probability of survival at 12 months was 0.93 for "responders" and 0.64 for "nonresponders" (p less than 0.005). Significant side effects necessitated drug withdrawal in four patients. Our data suggest that survival in patients with CAD is better when complex VPBs can be suppressed.

Abnormal quinidine binding in survivors of prehospital cardiac arrest

Quinidine binding was studied in 15 survivors of prehospital cardiac arrest and was compared to 18 normal individuals and 20 patients with coronary artery disease. The unbound quinidine fraction was 6.3 +/- 2.8% in the survivors of prehospital cardiac arrest, a value significantly lower than normal individuals (unbound quinidine fraction = 9.9 +/- 3.0%, p less than 0.005). Furthermore, unbound quinidine fraction correlated with interdose quinidine half-life in the six survivors of prehospital cardiac arrest where this could be measured (r = 0.79, p less than 0.05). The resultant quinidine interdose half-life was significantly prolonged (10 +/- 3 hours) when compared to normal (6 +/- 2 hours, p less than 0.02). The reduction in free drug fraction in cardiac arrest survivors was a nonspecific finding in that free drug fraction was also reduced in the patients with coronary artery disease (unbound quinidine fraction = 7.4 +/- 3%) and was independent of the alpha-1-glycoprotein concentration. Therefore survivors of prehospital cardiac arrest have a mean 40% reduction in free quinidine drug fraction which results in less free drug at any given total drug concentration and may relate to quinidine pharmacokinetics and pharmacodynamics in this patient group.

Efficacy of amiodarone during long-term treatment of potentially dangerous ventricular arrhythmias in patients with chronic stable ischemic heart disease

Amiodarone was administered orally to 30 patients with chronic stable coronary artery disease and severe ventricular arrhythmias. Control studies revealed frequent (more than 30/hr) ventricular premature beats (VPBs) (27 patients), bigeminy (21 patients), couples (29 patients), R-on-T phenomenon (14 patients), ventricular tachycardia (16 patients), and ventricular fibrillation (1 patient). Two 24-hour Holter recordings and stress tests were performed before treatment, and an average of 3.6 per patient were done during treatment. Amiodarone caused suppression of all ventricular arrhythmias in 13 (43%) of the 30 patients and suppression of all complex forms and greater than 90% reduction of VPB number in 14 patients (47%) during a follow-up of 12.4 months. The mean dose was 590 mg/day in the 27 responders and 300 mg/day in the three nonresponders. A similar antiarrhythmic response was observed during stress testing. One of the 30 patients died due to massive pulmonary embolism and no arrhythmias were detected. In addition, amiodarone suppressed the occurrence of anginal pain and effort-induced ST changes in 9 of 10 patients and in 11 of 13 patients, respectively. The rate-pressure product and peak heart rate were significantly reduced in all patients. Our results suggest that amiodarone may be ideally suited for treatment of ventricular arrhythmias and for possible prevention of sudden death in patients with ischemic heart disease.

Sudden cardiac death. Helping those at risk survive

Sudden cardiac death continues to pose a major public health problem in the United States. The underlying cause in the vast majority of patients is arteriosclerotic heart disease, and the pathophysiologic mechanisms are ventricular tachycardia and ventricular fibrillation. In patients identified to be at great risk for sudden cardiac death, both noninvasive and invasive techniques are available to help guide antiarrhythmic therapy. When arrhythmias occur frequently, noninvasive techniques may be adequate to allow sequential pharmacologic testing until an effective regimen can be defined. However, in patients whose frequency of arrhythmia at rest is low, provocative techniques are required. In patients for whom a successful pharmacologic regimen is defined, the outlook is good and the chance of sudden cardiac death is considerably decreased.

Effect of moricizine hydrochloride in reducing chronic high-frequency ventricular arrhythmia: results of a prospective, controlled trial

The antiarrhythmic efficacy of moracizin HCl (Ethmozine), a new oral phenothiazine derivative, was evaluated in 20 patients with chronic high-frequency ventricular arrhythmia confirmed by multiple ambulatory electrocardiographic recordings. Comparison with 72 +/- 24 hours (+/- standard deviation) of ambulatory recordings on moracizin treatment (average dose 295 +/- 58 mg 3 times daily or 9.8 +/- 1.0 mg/kg/day) was made. Maximal treadmill exercise provocation of arrhythmia and echocardiographic studies to detect effects on left ventricular function were also compared. The group had an average of 378 +/- 97 ventricular premature beats (VPBs) per hour while receiving placebo, with a mean VPB grade of 3.4 +/- 1.1 (modified Lown). When the patients received moracizin HCl, VPB frequency was reduced 53% (p less than 0.01), to a mean VPB grade of 2.2 +/- 1.4 (p less than 0.05). Seventy percent of the patients (14 of 20) showed a reduction in VPB frequency that exceeded the maximal expected variation; in 3 the frequency did not change and in 3 it increased with moracizin HCl. Resting electrocardiographic changes consisted of modest prolongations of PR interval (0.03 second) and QRS duration (0.02 second); however, QT prolongation was not observed. Heart rate and blood pressure at rest and peak exercise, exercise-related arrhythmia, exercise durations and echocardiographic measures of left ventricular function were unchanged by moracizin HCl compared with placebo. Side effects of moracizin++ HCl at these dosages were minimal (diarrhea in 1 patient, dizziness in 1 and diaphoresis in 1), although 2 patients tested at higher dosages had sustained ventricular tachycardia that may have been related to moracizin HCl.(ABSTRACT TRUNCATED AT 250 WORDS)

Prognosis after sudden cardiac death without associated myocardial infarction: one year follow-up of empiric therapy with amiodarone

Thirty-three consecutively referred patients with cardiac arrest from ventricular arrhythmias unassociated with a new acute myocardial infarction (AMI) were commenced on amiodarone therapy and followed for a minimum of 12 months. The dose of amiodarone was adjusted to maximum tolerance and not according to the incidence of asymptomatic ventricular premature complex activity. Eight patients died including five sudden deaths. Five out of the eight deaths occurred either within 3 months of therapy or when the dose of amiodarone was less than 400 mg/day. The majority of patients were found to have corneal microdeposits or either thyroid or liver function abnormalities, although none had any clinical manifestation. Ten patients had neurologic side effects. In summary, although the overall cardiac mortality seemed to be reduced by amiodarone therapy and the drug appears to be well tolerated by patients, its role in the prophylaxis against recurrent ventricular fibrillation may be enhanced by a regimen of higher loading and maintenance doses.