Comparison of event rates and survival in patients with unexplained syncope without documented ventricular tachyarrhythmias versus patients with documented sustained ventricular tachyarrhythmias both treated with implantable cardioverter-defibrillators

Patients with unexplained syncope and inducible ventricular tachyarrhythmias during electrophysiologic testing have an increased cardiac mortality rate. We compared event rates and survival of 178 patients with unexplained syncope and no documented ventricular arrhythmias (syncope group) versus 568 patients with documented sustained ventricular tachycardia (VT or fibrillation (VF) (VT/VF group) treated, as part of a lead (Ventritex TVL) investigation, with similar implantable cardioverter-defibrillators (ICDs) capable of extensive data storage. The 2 groups shared similar clinical characteristics. The mean follow-up was 11 months for the syncope group and 14 months for the VT/VF group. The mean time from device implantation to first appropriate therapy was similar in the 2 groups (109 +/- 140 vs 93 +/- 131 days, p = 0.40). Actuarial probability of appropriate ICD therapy was 49% and 55% at 1 and 2 years, respectively, in syncope group and 49% and 58% in VT/VF group (p = 0.57). Recurrent syncope was associated with ventricular tachyarrhythmias in 85% and 92% of the syncope group and VT/VF group, respectively (p = 0.54). At 2 years, actuarial survival was 91% in the syncope group and 93% in VT/VF group (p = 0.85). We conclude that patients treated with ICD with unexplained syncope and induced VT/VF have an equally high incidence of appropriate ICD therapy and low mortality compared with similar patients with documented VT/VF. These findings, plus the high association between recurrent syncope and ventricular arrhythmias, indicate that VT/VF are likely etiologies in selected patients with unexplained syncope and support ICD therapy in such cases.     

Reproducibility of arrhythmia induction with intracardiac electrophysiologic testing: patients with clinical sustained ventricular tachyarrhythmias

In order to characterize the day to day reproducibility of arrhythmias provoked during electrophysiologic stimulation, 114 patients with documented sustained clinical ventricular tachyarrhythmias were studied. Two baseline electrophysiologic tests were performed in the drug-free state and within 6 to 24 hours of one another. There was a significant increment (p less than or equal to 0.02) in the induction of sustained ventricular tachyarrhythmias as the number of programmed extrastimuli increased from one (10% induction) to four (64% induction). Provoked arrhythmias were observed to be more frequently nonreproducible (as reflected in a major change in rate or duration, or both, of an induced ventricular arrhythmia between baseline tests) as the number of extrastimuli increased from one (7%) to four (27%). Nonreproducibility with three and four extrastimuli was not significantly greater than when two extrastimuli were utilized. Electrophysiology-directed drug trials should be interpreted in light of this observed variability in induced arrhythmias.     

Prospective comparison of Holter monitoring and electrophysiologic study in patients with coronary artery disease and sustained ventricular tachyarrhythmias

Baseline 24-hour Holter monitoring (HM) and electrophysiologic study (EPS) were compared in 43 consecutive patients with coronary artery disease who had sustained ventricular tachyarrhythmias to determine the fraction of patients in whom each could be performed and the fraction in whom each could be used to guide therapy. Patients were excluded from HM if sustained ventricular tachycardia (VT) requiring termination occurred and from EPS if heart failure was sufficiently severe to cause excessive risk. More patients completed EPS than HM (90% vs 71%), but this difference was not statistically significant (p = 0.12). Overall, HM detected arrhythmias suitable for antiarrhythmic drug assessment in 50% of patients: 30 or more ventricular premature complexes (VPCs) per hour in 50%, 10 or more VPC pairs in 44%, 5 or more runs in 19%, and 10 or more pairs and runs in 44%. Sustained monomorphic VT suitable for electropharmacologic testing was induced at EPS in 82% (p = 0.003 vs HM). Drug efficacy could be assessed in 70% of patients evaluated by HM, compared with 96% evaluated by EPS (p = 0.02). Thus, in consecutive coronary patients with sustained ventricular tachyarrhythmias, EPS could be used to guide therapy more frequently than HM.     

Role of programmed ventricular stimulation in patients with idiopathic dilated cardiomyopathy and documented sustained ventricular tachyarrhythmias: inducibility and prognostic value in 102 patients

The role of programmed ventricular stimulation (PVS) in patientsat high risk of sudden death related to idiopathic dilated cardiomyopathy(DCM) is still controversial The possible reason is that moststudy series have been too small or that only a few patientshad documented sustained ventricular tachyarrhythmias. This study therefore, looked at PVS performed in 102 patientswith DCM and documented sustained ventricular tachycardia (VT;n=63) or ventricular fibrillation (VF; n=39). Sustained VT wasinduced in 27 of 63 patients (43%) with documented sustainedVT and in 14 of 39 patients (36%) with documented VF (ns). VFwas induced in nine patients (14%) with a history of sustainedVT and in seven (18%) with a history of VF (ns). At a mean follow-upof 32±15 months, sudden death occurred in 14 (14%) patients,a rate similar in both patients with documented VT and VF (ns).Incidence of sudden death at 36 months was 6% in patients withinducible sustained VT/VF compared to 29% in patients withoutinducible VT/VF (P<0·05) A favourable drug regimen(response to drug and no intolerable side effects) was obtainedby serial drug testing in 25 of all 102 patients (25%). A cardioverterdefibrillator (ICD) was implanted in 32 patients, in 63% ofwhom discharges were observed during 18±11 months offollow-up; only one patient (3%) died suddenly. Thus, in patients with DCM, there was no relationship betweendocumented and inducible ventricular tachzyarrhythmias, andinitiation of sustained VT or VF had little prognostic valuefor the prediction of subsequent sudden death. Wherever antiarrhythmic drug therapy was of limited value, implantationof an ICD may improve the prognosis of these high risk patients.     

Determinants of the outcome of electrophysiologic study in patients with ventricular tachyarrhythmias

To determine those factors predictive of the ability to both initiate and suppress ventricular tachyarrhythmias during electrophysiologic study, the results of programmed cardiac stimulation were evaluated in 261 patients: 66 presenting with nonsustained ventricular tachycardia, 91 with sustained ventricular tachycardia and 104 with ventricular fibrillation. Multivariate logistic regression analysis revealed that the presenting arrhythmia was a potent and independent predictor of the ability to provoke ventricular arrhythmias at electrophysiologic study; a history of myocardial infarction and male sex were also significant independent predictors. Of patients presenting with sustained ventricular tachycardia, 89% (81 of 91) had inducible ventricular arrhythmias compared with 61 (40 of 66) and 66% (69 of 104) of patients with nonsustained ventricular tachycardia and ventricular fibrillation, respectively. Complete suppression of inducible arrhythmias could be achieved in only 52% (34 of 66) of patients with sustained ventricular tachycardia, compared with 73 (24 of 33) and 75% (46 of 61) of patients presenting with nonsustained ventricular tachycardia and ventricular fibrillation, respectively. Multivariate analysis showed that the major independent determinants of the ability to suppress inducible arrhythmias were the number of drug trials performed before electrophysiologic study (inversely correlated) and the nature of the induced arrhythmia. The nature of the presenting clinical arrhythmia is, therefore, a highly significant and independent predictor of the ability to induce ventricular arrhythmias during electrophysiologic testing and an important determinant of the ability to suppress induced arrhythmias in patients with spontaneous ventricular tachyarrhythmias.     

Is a baseline electrophysiologic study mandatory for the management of patients with spontaneous, sustained, ventricular tachyarrhythmias?

Should the patient being treated for spontaneous, sustained ventricular tachycardia (VT) or ventricular fibrillation (VF) routinely undergo a baseline, diagnostic, catheter electrophysiologic (EP) study? The potential patient advantages of such a policy include identification of the tachyarrhythmia-initiating episodes of presumed VT or VF, prediction of the subsequent risk of VT/VF recurrences, identification of VT mechanisms amenable to cure by catheter ablation, assessment of the response of a patient's VT to attempts at pace termination, evaluation of the patient's candidacy for some of the approaches to VT/VF therapy selection, and enhancement of our understanding of the mechanisms and therapeutics of VT/VF. Disadvantages of such a policy include patient discomfort, patient risks, and cost. Recognizing that the decision to perform a baseline catheter EP study in a patient with VT/VF must be based on an individualized, patient-based, risk-benefit analysis; this review details each of the advantages and disadvantages of doing so to identify patient populations for whom a baseline catheter EP study is or is not usually indicated.     

Role of drug therapy for sustained ventricular tachyarrhythmias

Antiarrhythmic drug therapy, broadly defined, is the mainstay of treatment and prevention of ventricular tachycardia (VT)/ventricular fibrillation (VF), which can lead to sudden death. This article evaluates the evidence for and appropriate use of class I antiarrhythmic drugs, class III antiarrhythmic drugs, beta-blockers, nondihydropyridine calcium-channel blockers, statins, angiotensin enzyme inhibitors, angiotensin receptor blockers, aldosterone blockers, and digoxin for antiarrhythmic benefits in patients who have a propensity for VT/VF and therefore are at risk of sudden death.     

The electrophysiologic effects of enoximone in patients with preexisting ventricular tachyarrhythmias

Electrophysiologic and hemodynamic effects of intravenous enoximone were studied in 15 male patients, mean age 62.2 years, with New York Heart Association classes II to IV congestive heart failure (coronary artery disease in 10 and idiopathic dilated cardiomyopathy in five patients; mean ejection fraction, 0.19). All patients had spontaneous ventricular tachyarrhythmias; eight had sustained ventricular tachycardia (VT), one had ventricular fibrillation, and six had nonsustained VT. Hemodynamic and electrophysiologic parameters including VT induction were determined before and during an intravenous infusion of enoximone. The cardiac index increased (2.49 +/- 0.89 to 2.96 +/- 0.78), and the pulmonary capillary wedge pressure decreased (22.4 +/- 13.2 to 10.0 +/- 9.0) after enoximone per predefined protocol endpoints. There was a significant decrease in spontaneous sinus cycle length, corrected sinus nodal recovery time, AH interval during atrial pacing, shortest cycle length at which 1:1 atrioventricular nodal conduction occurred, and refractory periods of the atrium, ventricle, and atrioventricular node. Enoximone did not alter the cycle length of induced VT, and there was no consistent change in the number of extrastimuli required for VT induction. A baseline 24-hour ECG recording was obtained on 14 patients (while receiving a long-term antiarrhythmic drug regimen, if needed) and repeated after 1 week and 1 month of oral enoximone therapy. There was no significant increase in the number of premature ventricular complexes per hour or VT episodes per 24 hours after 1 week or 1 month of therapy with enoximone. However, if four patients who received amiodarone and may not yet have reached steady state were excluded from analysis, there was a significant increase in the frequency of premature ventricular complexes per hour 1 month after initiation of enoximone. We conclude that intravenous enoximone reduces pulmonary capillary wedge pressure and increases cardiac output in most patients. Intravenous enoximone in doses sufficient to have hemodynamic effects shortens atrial, ventricular, and atrioventricular nodal refractoriness and decreases AV nodal conduction time but has no consistent effect on VT induction or VT cycle length. The frequency of spontaneous ventricular ectopy may increase in some patients after oral enoximone, but its clinical significance is undefined. Enoximone may be administered cautiously to patients with congestive heart failure and preexisting ventricular tachyarrhythmias.     

A prospective comparison of programmed ventricular stimulation with triple extrastimuli versus single and double extrastimuli during infusion of isoproterenol

This prospective study compared the yield of programmed ventricular stimulation with single and double extrastimuli during an infusion of isoproterenol with that of programmed stimulation with triple extrastimuli. The subjects of this study were 58 patients who underwent programmed stimulation and did not have inducible ventricular tachycardia (VT) with single or double extrastimuli at two basic drive cycle lengths and at two right ventricular sites; 17 patients had a history of uniform VT unrelated to exercise, and 41 had no history of documented or suspected VT or ventricular fibrillation (VF). Programmed stimulation was performed with triple extrastimuli at both right ventricular sites. Isoproterenol was infused as a dose titrated to increase the sinus rate by 25% or to a rate of 100 beats/min, whichever was greater, and stimulation then was repeated with single and double extrastimuli. Among the 17 patients with a history of uniform VT, the clinical VT was induced by three extrastimuli in five patients (29%) and by two extrastimuli during isoproterenol infusion in six patients (35%, p greater than 0.05). Among the total study population of 58 patients, nonclinical multiform VT or VF was induced by three extrastimuli in 29 patients (50%), and by two extrastimuli during isoproterenol infusion in 15 patients (26%, p less than 0.05). Therefore stimulation with two extrastimuli during isoproterenol infusion has the same probability of inducing a clinical form of VT as does stimulation with extrastimuli, but the former has a significantly lower probability of inducing nonclinical multiform VT and VF.     

Clinical and electrophysiologic determinants, treatment and survival of patients with sustained malignant ventricular tachyarrhythmias occurring late after myocardial infarction

To assess the clinical and electrophysiologic determinants, treatment and survival of patients with sustained malignant ventricular tachyarrhythmias late after myocardial infarction, a total of 108 patients (mean age 61 +/- 10 years) were studied. Thirty-two patients (Group I) had sustained ventricular tachyarrhythmias 8 to 60 days (mean 13 +/- 9) after acute myocardial infarction. The remaining 76 patients (Group II), who served as a control group, had no sustained ventricular tachyarrhythmias less than or equal to 60 days after infarction. The most significant independent determinants of sustained ventricular tachyarrhythmias late after infarction were the presence of late potentials (chi square = 16.07, p = 0.0001), defined as an abnormal signal-averaged QRS complex in association with an abnormal root-mean-square voltage in the terminal 40 ms of the QRS complex, and an abnormal ejection fraction of less than 40% (chi square = 10.09, p = 0.001). Sustained ventricular tachycardia was induced in 27 (96%) of 28 Group I patients. Among the 32 patients in Group I, antitachycardia therapy included antiarrhythmic drug therapy as the sole preventive measure in 14 (44%); map-guided surgery or coronary artery bypass surgery, or both, in 14 (44%) and the automatic cardioverter-defibrillator in 4 (12%). The arrhythmias were rendered noninducible in 83% of patients after map-guided surgery and in 41% after drug therapy. During a follow-up period of 20 +/- 14 months, five Group I patients (15%) had an arrhythmic event and four (9.3%) had a cardiac-related death. All five patients who had an arrhythmic event were receiving antiarrhythmic drug therapy.(ABSTRACT TRUNCATED AT 250 WORDS)     

Spontaneous sustained ventricular tachyarrhythmias during treatment with type IA antiarrhythmic agents

Twenty-six patients who developed their first clinical episode of sustained ventricular tachycardia (VT) or ventricular fibrillation (VF) while taking type IA antiarrhythmic agents for more benign rhythm disturbances were rechallenged with the identical drug during electrophysiologic testing. Patients with these new drug-associated spontaneous ventricular arrhythmias often manifested a preexisting substrate for such arrhythmias: sustained VT or VF was induced in 65% of patients at baseline, and in 58% of patients when tested with their previously taken antiarrhythmic drug. Among those without inducible sustained ventricular arrhythmias in the drug-free state, 78% remained free of inducible sustained arrhythmias when tested with the same drug they had been taking at the time of the clinical arrhythmia. Even patients without a definable electrophysiologic substrate for sustained VT or VF remained at risk for arrhythmia recurrence if treated with alternative antiarrhythmic medications: 40% of such patients who continued to receive an antiarrhythmic agent different from that being administered when their clinical VT or VF occurred had recurrent spontaneous ventricular tachyarrhythmias during follow-up. Thus, patients with drug-associated clinical sustained ventricular tachycardias form a heterogenous group that should be evaluated individually and not empirically managed for a "proarrhythmic effect" simply by antiarrhythmic drug withdrawal or drug substitution.     

Role of electrophysiologic study (EPS)-guided preventive therapy for the management of ventricular tachyarrhythmias in patients with heart failure.

BACKGROUND: Ventricular tachyarrhythmias (VT/VF) are 1 of the most important factors determining the prognosis of patients with heart failure (HF). Although priority is given to implantable cardioverter defibrillator (ICD) therapy for the prevention of sudden cardiac death, electrophysiologic-study (EPS)-guided preventive therapy could be important for reducing the number of cardiac events. METHODS AND RESULTS: Of 864 patients with a history of HF, an EPS was performed in 168 and 121 had inducible VT/VF. Under the basic therapy of an ICD, additional catheter ablation was attempted for 95 of 124 monomorphic VT foci in 74 patients, and 78 of the VT were successfully ablated. The prognoses were compared among 5 patient groups with different results for the EPS and catheter ablation: (1) success group (n=43), (2) failure group (n=15), (3) not attempted group (n=16), (4) VF group (n=47), and (5) no inducible VT/VF group. During a follow-up period of 31+/-22 months, the incidence of VT/VF was lower in the success and no inducible VT/VF groups than in the other groups (p=0.0018), although a significant difference was not observed for the total deaths. CONCLUSION: EPS-guided preventive therapy using an ICD and catheter ablation can be useful, at least for the reduction of arrhythmic events in patients with HF.     

Noninvasive electrophysiologic study using standard permanent pacemakers in patients with spontaneous sustained ventricular tachycardia or ventricular fibrillation

Permanent pacemakers capable of noninvasive electrophysiologic testing were used to study and treat 26 patients with spontaneous sustained ventricular tachycardia (VT) or fibrillation (VF). One hundred nine episodes of sustained VT or VF were induced in these patients. In 8 patients spontaneous VT was reverted by noninvasive means. Drug changes based on noninvasive testing were made in 12 patients. In the 1- to 67-month follow-up period, drug therapy based on noninvasive electrophysiologic testing was predictive of outcome in patients with spontaneous arrhythmias. Thus, noninvasive electrophysiologic testing using permanent pacemakers is a useful method for studying and treating patients with recurrent sustained ventricular arrhythmias.     

Usefulness of electrophysiologic testing in evaluation of amiodarone therapy for sustained ventricular tachyarrhythmias associated with coronary heart disease

The prognostic importance of electrophysiologic studies in patients with sustained ventricular tachyarrhythmias treated with amiodarone was prospectively studied in 100 consecutive patients. Sustained ventricular tachycardia (VT)/ventricular fibrillation (VF) was inducible in all patients before amiodarone therapy. After amiodarone administration 2 groups of patients were identified. In group 1 patients the ventricular tachyarrhythmia was no longer inducible and in group 2 patients the arrhythmia remained inducible. In group 1, no recurrent arrhythmia occurred during a follow-up of 18 +/- 10 months. In group 2, 38 of 80 patients (48%) had arrhythmia recurrence during a follow-up of 12 +/- 9 months. The difference between group 1 and 2 could not be explained by clinical variables, amiodarone doses or plasma concentrations, or electrocardiographic variables. In patients in whom cardiovascular collapse or other severe symptoms where noted during electrophysiologic study after amiodarone treatment, recurrences caused sudden death (n = 12). However, in patients in whom the induced arrhythmia produced moderate symptoms, the recurrent arrhythmia was nonfatal VT (n = 26). Electrophysiologic testing provides clinical guidance and predicts prognosis in patients treated with amiodarone as it does for the evaluation of other antiarrhythmic agents.     

Predictors of inducible sustained ventricular tachyarrhythmias in patients with coronary artery disease

To determine predictors of inducible sustained ventricular tachycardia or fibrillation by programmed electrical stimulation in patients with coronary artery disease and ventricular tachyarrhythmias, 14 clinical and angiographic variables were analyzed in 60 consecutive patients. All patients had angiographically documented coronary artery disease and symptomatic ventricular arrhythmias (sustained ventricular tachycardia in 21, ventricular fibrillation in 21 and nonsustained ventricular tachycardia in 18). Baseline programmed electrical stimulation while the patient was not taking antiarrhythmic drugs was performed with use of single, double and triple extrastimuli and burst pacing from two right ventricular sites. The variables analyzed were presenting arrhythmia; presence, frequency and complexity of ventricular ectopic activity on baseline 24 h electrocardiographic (Holter) monitoring; greater than or equal to 70% narrowing in either the left anterior descending, proximal left anterior descending, right coronary or circumflex coronary artery (independently assessed); single, double or triple vessel coronary disease; anterior, apical or inferior wall motion abnormalities; segmental dyskinesia and ejection fraction. Thirty-seven patients (62%) had inducible sustained ventricular tachycardia (rate greater than 100 beats/min, duration greater than 30 s or requiring cardioversion) and two patients (3%) had ventricular fibrillation induced. Eleven patients (18%) had nonsustained ventricular tachycardia (duration greater than or equal to 3 beats, less than 30 s) induced and 10 patients (17%) had no inducible arrhythmia (duration less than 3 beats). Multivariate stepwise logistic regression analysis identified three independent variables predictive of inducible sustained ventricular arrhythmias: sustained ventricular tachycardia as the presenting arrhythmia (p = 0.004), proximal left anterior descending artery lesion (p = 0.002) and anterior wall motion abnormality (p = 0.005).(ABSTRACT TRUNCATED AT 250 WORDS)     

Safety and efficacy of sotalol in patients with drug-refractory sustained ventricular tachyarrhythmias

The safety and efficacy of oral sotalol, an investigational beta-adrenergic blocker with class III antiarrhythmic drug properties, were examined in a multicenter study in 236 patients with sustained ventricular tachyarrhythmias. In 104 patients, the index arrhythmia was a cardiac arrest, and all patients had undergone at least 3 previous unsuccessful antiarrhythmic trials (mean = 5 per patient). In the 106 patients assessed by programmed electrical stimulation, sotalol completely suppressed induction of ventricular tachycardia (VT) in 33 (31%) and rendered VT slower (greater than 100 ms prolongation of cycle length) or more difficult to induce in 29 (27%). Using continuous 24-hour ambulatory monitoring methods, sotalol complete- and partial-response rates were 51 and 12%, respectively. Of the 236 acute-phase patients, 151 were discharged receiving long-term sotalol therapy. The median sotalol dose was 480 mg/day. At a mean follow-up of 346 +/- 92 days, 27 patients (18%) had recurrence of sustained arrhythmia; 9, sudden death; 11, sustained VT; 5, automatic defibrillator discharge; and 2, syncope. Adverse effects forced discontinuation of therapy in 10 patients (7%): 6 secondary to symptomatic bradyarrhythmia, 2 due to refractory heart failure, 1 due to torsades de pointes, and 1 from bronchospasm. Life-table analysis of sotalol's overall long-term efficacy at 6, 12 and 18 months were 80, 76 and 72%, respectively. Although mean follow-up was short (less than 1 year), neither acute-phase programmed stimulation nor 24-hour ambulatory monitoring responses were significantly predictive of subsequent arrhythmic outcome. Proarrhythmia was documented in 18 patients (7%), 17 during the acute phase and 1 during long-term follow-up.(ABSTRACT TRUNCATED AT 250 WORDS)     

Isoproterenol reversal of antiarrhythmic effects in patients with inducible sustained ventricular tachyarrhythmias

Seventeen patients (16 men and 1 woman) were challenged with isoproterenol after their initially inducible sustained ventricular tachyarrhythmia (monomorphic tachycardia in 14 patients and fibrillation in 3) was completely suppressed by class I antiarrhythmic drugs. Coronary artery disease was documented in 11 patients, dilated cardiomyopathy in 2 and no structural heart disease in the remaining 4 patients. The initial presentation was aborted sudden cardiac death (five patients), syncope (eight patients) and symptomatic nonsustained ventricular tachycardia (four patients). The antiarrhythmic drug that rendered the initial ventricular tachyarrhythmias noninducible was class IA in 11 cases, class IC in 5 and combined class IA and IB in 1. The original ventricular tachyarrhythmia became reinducible in 10 patients (group A) and remained noninducible in 7 patients (group B) after isoproterenol infusion at a rate necessary to achieve a 20% increase in heart rate. Despite the results of isoproterenol challenge, all patients were maintained on their electrophysiologically guided antiarrhythmic regimen. During a mean follow-up period of 13 +/- 9 months, 3 of the 10 patients in group A experienced clinical recurrence of tachyarrhythmia; no recurrence was noted in group B. In conclusion, reinducibility of ventricular tachyarrhythmia after beta-adrenergic stimulation seems to identify a subgroup of patients at high risk of subsequent arrhythmic events. Beta-adrenergic blockade or surgical therapy may be indicated in some patients with a positive isoproterenol challenge.     

Antiarrhythmic efficacy of solitary beta-adrenergic blockade for patients with sustained ventricular tachyarrhythmias

To assess the efficacy and predictability of solitary beta-adrenergic blocker (BB) therapy for ventricular tachyarrhythmia (VT), 30 patients (16 men and 14 women) with a mean age of 55 years, who initially had sustained ventricular tachycardia (70%) or ventricular fibrillation (30%), were studied. Results of baseline arrhythmia tests showed VT on ECG monitoring in 57% of the patients, during exercise in 50%, induced by programmed stimulation in 69%, increasing to 86% during isoproterenol. BB therapy prevented inducible VT during programmed stimulation in 37% of the patients, prevented VT on ECG monitoring in 54%, and prevented VT during exercise in 83%. Long-term BB therapy was given to 24 of 30 patients, whereas six other patients with hemodynamically unstable VT during BB therapy received other long-term treatment. During a mean follow-up of 824 days, 6 of 24 patients had recurrent VT. BB therapy was discontinued in two patients because of side effects. Long-term success was predicted by left ventricular ejection fraction greater than 45%, absence of coronary disease, and age less than 60 years (all p less than 0.02). Neither suppression of arrhythmia during exercise testing, nor results of programmed stimulation or ECG monitoring were predictive of outcome. Thus beta-adrenergic blockers can be effective as solitary antiarrhythmic therapy in selected patients with VT.