Suppression of the repetitive ventricular response: an index of long-term antiarrhythmic effectiveness of aprindine for ventricular tachycardia in man

Reduction in sudden death and total mortality by antiarrhythmic therapy evaluated by electrophysiologic drug testing: criteria of efficacy in patients with sustained ventricular tachyarrhythmia

Reports of the results of electrophysiologic testing of antiarrhythmic regimens have concentrated on inducibility of ventricular tachycardias during drug treatment. Many drug regimens, however, affect the tachycardia but fail to prevent its initiation. In this study, 258 patients who underwent serial electrophysiologic studies were followed up. The patients were divided into three groups on the basis of the results of electrophysiologic testing. Group 1 included patients in whom the initiation of ventricular tachycardia was prevented by the drug regimen. In groups 2 and 3 the ventricular tachycardia was still inducible with the discharge drug regimen. In group 2, the drug regimen demonstrated a beneficial response (that is, the tachycardia cycle length increased by greater than 100 ms and the tachycardia did not produce severe symptoms). In group 3, the regimen did not produce a beneficial response. During follow-up, recurrence of sustained ventricular tachycardia occurred in 7 (7%) of 103 group 1 patients but in 20 (39%) of 51 and 52 (50%) of 104 group 2 and 3 patients, respectively. However, the total mortality and sudden death mortality rates were substantially reduced in group 2 (12 and 4%, respectively) compared with group 3 (39 and 34%). In fact, the total mortality and sudden death mortality in groups 1 and 2 were not significantly different. Thus, under certain circumstances, a drug regimen that produces a beneficial response may be an acceptable clinical alternative, particularly when no regimen prevents induction of ventricular tachycardia.

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.

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.

Treatment of life-threatening ventricular arrhythmias by a combination of antiarrhythmic drugs and right ventricular pacing

Thirteen patients with intractable ventricular arrhythmias were studied; they underwent long-term treatment by a combination of antiarrhythmic drugs and ventricular pacing. Eleven patients had a history of tachycardia and two had torsade de pointes; eleven of thirteen had had cardioversion and/or defibrillation. Prior to permanent pacemaker implantation, temporary pacing in the VVI mode was used in combination with one or more of the following drugs: amiodarone, aprindine, digitalis, metoprolol, mexiletine, procainamide, pindolol, propranolol, or quinidine. Various pacing rates were tried; when permanent pacing was instituted, a unipolar system which was at least rate-programmable was used. Right ventricular VVI pacing, combined with drug therapy, was successful in ten of thirteen patients. Five of the ten patients are alive and free of arrhythmias after 78, 72, 72, 54, and 11 months, respectively. Although five patients died (after 60, 48, 30, 24, and 9 months, respectively), none of the deaths were related to arrhythmias. We suggest that in patients with ventricular arrhythmias refractory to conventional treatment, a therapeutic trial of right ventricular VVI pacing in combination with a drug regimen be used.

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)

Prevalence and clinical significance of the repetitive ventricular response during sinus rhythm in coronary disease patients

The prevalence of the repetitive ventricular response (RVR) after single and double premature stimulation during sinus rhythm or a paced supraventricular rhythm at a rate of 85 bpm was assessed in 343 patients (group 1: 237 patients studied prospectively who were referred for coronary arteriography and ventriculography; group 2: 44 patients after recent acute myocardial infarction; group 3: 61 patients with documented ventricular tachycardia and/or fibrillation). In group 1 patients, RVR testing was performed from both the right ventricular apex (n = 237) and outflow tract (n = 190), whereas in the remaining patients only the apex was stimulated. In group 1, RVR after a single premature stimulus occurred in 21.9% and after two stimuli in 63.2%. In patients with normal left ventricular (LV) function (n = 63) the prevalence of RVR after a single stimulus was significantly less (9.5%) than in those with LV dysfunction (n = 174;26.4%,p less than 0.01). However, after double stimulation, there was no longer any difference. In group 2, the prevalence of RVR was 25% after one and 34.1% after two premature stimuli. In group 3 patients, RVR was observed in only 14.8% after one and in 41% of patients after two premature stimuli. Ventricular tachycardia (greater than or equal to 10 QRS) was induced in nine patients during a supraventricular rhythm. Two hundred thirty-seven patients of group 1, who were prospectively studied in order to assess the prognostic significance of the RVR, were followed for a mean period of 27.2 +/- 10.7 months.(ABSTRACT TRUNCATED AT 250 WORDS)

The repetitive ventricular response: relationship to ventricular fibrillation threshold in dogs

The experiments investigated the hypothesis that the occurrence of repetitive ventricular responses elicited by the ventricular extrasystole (VES) technique are an indicator of ventricular vulnerability to fibrillation. A comparison was made between the incidence of repetitive responses elicited by the VES technique and the minimum electrical energy (VFT technique) necessary to elicit repetitive responses and ventricular fibrillation in normal dogs, dogs with acute infarction, and dogs with chronic infarction. The VES technique produced repetitive responses in 14 of 46 sites. Responses were of at least three types: (1) bundle branch re-entry; (2) activation at the pacing site, and (3) activation at the infarct zone. In contrast repetitive responses and the onset of fibrillation produced by the VFT technique appeared to be a single type with earliest activation at the pacing site. There were no differences in the ventricular fibrillation thresholds between dogs with and without repetitive responses produced by the VES technique. Thus the incidence of VES technique-induced repetitive responses is not a reasonable predictor of ventricular vulnerability to fibrillation. However, in 2 dogs with lower ventricular fibrillation thresholds, repetitive responses originating at the infarct zone were induced by the VES technique. Occurrence of these repetitive responses may be indicative of ventricular vulnerability to fibrillation.

Role of electrophysiologic techniques in the selection of antiarrhythmic drug regimens for ventricular arrhythmias

Programmed electrical stimulation of the heart provides a useful new technique for guiding the selection of antiarrhythmic drug regimens in selected patients with ventricular tachycardia (VT) or ventricular fibrillation. The technique of programmed electrical stimulation has been applied successfully in patients with recurrent sustained VT, out-of-hospital ventricular fibrillation and unexplained syncope in the presence of structural heart disease. The complete suppression of VT induced by programmed electrical stimulation by a drug regimen is highly predictive of freedom from both recurrent VT and sudden death. In addition, this technique may hold promise as a means of assessing the arrhythmogenic effects of antiarrhythmic drugs in selected patients.

Ventricular ectopy: etiology, evaluation, and therapy

Ventricular ectopy occurs commonly. Its significance is related to the degree of complexity and the associated cardiac substrate. Coronary artery disease is the most frequent underlying cause, followed by cardiomyopathy and valvular disease. Symptomatic ventricular arrhythmias require treatment, whereas benign simple ventricular ectopy does not; however, the treatment of asymptomatic high-grade ventricular ectopy remains controversial. Therapy first must be directed toward the cardiac disease. Evaluation of the patient includes Holter monitoring, echocardiography, radionuclide studies, exercise testing, cardiac catheterization, and electrophysiologic testing. Programmed stimulation is useful in the diagnosis and prognosis of ventricular tachycardia, as well as in the evaluation of drug regimen efficacy. After treatment of ischemia and/or failure, specific antiarrhythmic agents, conventional and investigational, alone or in combination, are systematically selected. Should medical therapy alone be insufficient, consideration is given to surgical procedures such as subendocardial resection or ventriculotomy, often in combination with bypass grafting, aneurysmectomy, or valvular replacement. Electronic devices, including pacemakers or automatic internal defibrillators, may also be useful in certain selected cases. Suggested guidelines are proposed for a standardized approach, although therapy for each patient must still be individualized.

Response to programmed ventricular stimulation: sensitivity, specificity and relation to heart disease

This prospective study of 100 patients evaluated the sensitivity and specificity of the repetitive ventricular response and ventricular tachycardia induced by programmed electrical stimulation for identifying patients with spontaneous ventricular tachyarrhythmias. The influence of underlying heart disease on such sensitivity and specificity was also evaluated. The repetitive ventricular response was sensitive (92 percent) for detecting patients with prior spontaneous ventricular tachyarrhythmias, but lacked specificity (57 percent); the rate of false positive responses was 43 percent. Inducible ventricular tachycardia was less sensitive (65 percent) but more specific (98 percent); the rate of false positive responses was only 3 percent. Among the 100 patients, 71 had heart disease, 29 did not. The presence of underlying heart disease had no significant effect on the sensitivity and specificity of repetitive ventricular responses or ventricular tachycardia induced by programmed stimulation; it did not increase the rate of false positive responses. It is concluded that (1) ventricular tachycardia induced with programmed ventricular stimulation is an excellent basis for guiding the management of clinically significant ventricular tachyarrhythmias, regardless of underlying heart disease; and (2) the repetitive ventricular response is not useful for this purpose because of its high rate of false positive responses among patients with or without significant heart disease.

The electropharmacology of acute drug testing using pacemakers

Acute drug testing in patients is useful to select prophylactic treatment for life-threatening or intractable tachycardias. This is generally done by induction of tachycardias with pacing. Acute studies that depend on temporary insertion of pacing electrodes do not determine efficacy in the same sense as longer term clinical drug trials because of the biased population referred for testing with pacemakers. However, the pharmacologic activity of compounds can be tested in terms of electrical functions such as conductivity and refractoriness not merely of the heart in general, but also of the arrhythmogenic focus. Such data can be directly applied to patients with similar arrhythmias, obviating the confusion often caused by interspecies and disease differences.

Treatment of frequent ventricular arrhythmia with encainide: assessment using serial ambulatory electrocardiograms, intracardiac electrophysiologic studies, treadmill exercise tests, and radionuclide cineangiographic studies

The effects of encainide on ventricular arrhythmia and left ventricular function were studied in 21 patients with chronic, high-grade ventricular arrhythmia using a prospective, 3-month, placebo-controlled, single-blind trial design. Encainide caused a 96% decrease in the average hourly frequency of ventricular premature complexes (VPCs) and comparable reductions in salvos of nonsustained ventricular tachycardia (VT) and episodes of sustained VT. Intracardiac electrophysiologic testing showed prolonged intraatrial and intraventricular conduction times and increased atrial, atrioventricular nodal, and ventricular refractory periods with both i.v. and oral encainide without His-Purkinje block, despite marked prolongation of HV and QRS intervals. Induced repetitive ventricular beating after ventricular extrastimuli in 15 patients showed persistent repetitive ventricular beating with chronic oral encainide in seven patients, four of whom had sustained VT within 2 months of treatment on encainide. Encainide did not reduce exercise capacity or left ventricular ejection fraction at rest or during supine exercise. Minor adverse effects of encainide in 11 of 21 patients included dose-related visual disturbances, dizziness and sinus pauses (less than 3 seconds). Major adverse effects included the new appearance of sustained VT in three of 20 patients (15%). Oral encainide effectively reduces the frequency and grade of VPCs, prolongs intracardiac conduction times, and does not impair left ventricular performance. However, it is associated with frequent minor side effects and uncommon but potentially severe major side effects (sustained VT), both of which apparently have a direct relationship to the size of the dose.

Aprindine-induced polymorphous ventricular tachycardia

Five cases of aprindine-induced polymorphous ventricular tachycardia (torsade de pointes) are presented. In four cases, polymorphous ventricular tachycardia appeared after the oral administration of 400 mg of aprindine. One patient had mild hypokalemia at the time of polymorphous ventricular tachycardia so that a direct cause and effect relation between the drug and the tachycardia cannot be established. All five patients manifested Q-T prolongation and recurrent syncope due to polymorphous ventricular tachycardia. In all five, polymorphous ventricular tachycardia subsided once administration of aprindine was discontinued.

Repetitive responses to single ventricular extrastimuli in patients with serious ventricular arrhythmias: incidence and clinical significance

Electrophysiologic studies were carried out in 85 patients with serious ventricular arrhythmias: 44 with recurrent sustained ventricular tachycardia (group A), 16 with recurrent nonsustained ventricular tachycardia (group B), and 25 with recent prehospital ventricular fibrillation not associated with acute myocardial infarction (group C). Programmed ventricular stimulation from the right ventricular apex included premature stimulation during normal sinus rhythm, atrial pacing, and ventricular pacing, as well as brief bursts of rapid ventricular pacing (RVP). A repetitive ventricular response (RVR) was defined as one or more non-stimulated premature ventricular depolarizations in response to a single paced premature ventricular depolarization during normal sinus rhythm or atrial pacing. RVRs were observed in seven of 44 (16%) group A patients, one of 16 (6%) group B patients, and three of 25 (12%) group C patients. In contrast, single and double premature ventricular stimuli during ventricular pacing and/or bursts of RVP resulted in the reproducible initiation of ventricular tachycardia in 40 of 44 (91%) group A patients, 10 of 16 (63%) group B patients, and 19 of 25 (76%) group C patients. We conclude that RVRs to single ventricular extrastimuli during normal sinus rhythm or atrial pacing are rare, and therefore are an insensitive index of susceptibility to serious ventricular arrhythmias in these patients.

Accuracy of the ventricular tachycardia-induction study for predicting long-term efficacy and inefficacy of antiarrhythmic drugs

We evaluated the prophylactic effect of antiarrhythmic agents against induction of ventricular tachycardia by extrastimulation in 51 patients with recurrent ventricular tachycardia. These patients subsequently underwent 58 long-term trials with tested agents. In 39 trials an agent predicted to be effective by electrophysiologic study was administered, and in 19 a drug predicted to be ineffective was used. There were no clinical differences between the two treatment groups. During a mean follow-up period of 8.2 months, arrhythmias recurred significantly less frequently in the group treated with drugs predicted to be effective than in the other group (P < 0.001); at six months 80 per cent of the patients in the former group were successfully treated, as compared with 33 per cent in the latter group. At 18 months the corresponding figures were 68 per cent and 11 per cent. We conclude that the arrhythmia-induction technique accurately predicts the clinical effectiveness of drugs used in the long-term treatment of recurrent ventricular tachycardia.

Repetitive beating after single ventricular extrastimuli: incidence and prognostic significance in patients with recurrent ventricular tachycardia

The incidence of repetitive ventricular beating in response to programmed single ventricular extrastimuli delivered during spontaneous rhythm was tabulated in 59 patients with recurrent ventricular tachycardia. Repetitive beating occurred in only nine patients (15 percent). The repetitive response seemed to be a result of bundle branch reentry in four subjects and possibly a result of other mechanisms in five. There was no difference in the incidence of repetitive beating or type of repetitive response in patients with and without ischemic heart disease. During an average patient follow-up period of 13.6 months, there were eight sudden and six nonsudden deaths. Life table analysis revealed a significantly greater incidence of sudden death in patients with ischemic than in patients with nonischemic heart disease. There was no significant difference in the incidence of sudden death in patients with and without repetitive beating. It is concluded that the repetitive response to single ventricular extra-stimulation is infrequent in patients with recurrent ventricular tachycardia, and that repetitive beating is not a prognostic indicator or an indicator of vulnerability to ventricular tachycardia.

Mechanism of the repetitive ventricular response in man

The electrophysiologic characteristics of the repetitive ventricular response that followed an electrically induced single premature ventricular complex were evaluated to determine its mechanism during atrial pacing or sinus rhythm in 30 patients. Seven patients had preexisting bundle branch block. His bundle or right bundle branch deflections did not precede the repetitive complex in 29 of the 30 patients, which implies that the proximal His-Purkinje system was not involved in the reentry circuit. In 24 of 30 patients the QRS axis ot the repetitive complex was divergent 45 degrees or more from the stimulated complex. In 22 of 30 patients the reprtitive complex had a right bundle branch block configuration. In 14 of 18 patients with two or more repetitive complexes, the QRS pattern changed from beat to beat, which implies that either the reentry pathway or conduction was changing. Thus, the repetitive ventricular response, which can be associated with clinically important ventricular arrhythmias, probably represents intraventricular rather than proximal His-Purkinje system reentry.

Prolongation of cardiac conduction times by intravenous aprindine in man

The acute electrophysiologic effects of intravenous aprindine were evaluated in 48 patients to assess the effect on conduction times and refractoriness in patients with severe cardiac disease and arrhythmias. The patients had not responded to conventional antiarrhythmic medications or had been unable to tolerate effective doses of conventional medications because of side effects. Eleven patients had an abnormal H-V interval, 9 had prolonged QRS duration and 22 had evidence of severe left ventricular dysfunction. Aprindine prolonged conduction transiently in the atria, the atrioventricular (A-V) node, the His-Purkinje system and the ventricles. The refractory times of the atria, the A-V node and the ventricles increased insignificantly, both functionally and statistically. Atrioventricular block did not develop in any patient, and side effects were minor. Thus, aprindine can be safely administered intravenously (10 to 15 mg/min) to severely ill patients with arrhythmias that are refractory to other medications even in the presence of underlying conduction system and myocardial disease.