Acebutolol therapy for ventricular arrhythmia. A randomized placebo-controlled double-blind multicenter study

Treatment of ventricular arrhythmias in the elderly

Underlying causes of ventricular tachycardia (VT) or complex ventricular arrhythmias (VA) should be treated if possible. Antiarrhythmic drugs should not be administered to treat asymptomatic individuals with complex VA and no heart disease. Beta-blockers are the only antiarrhythmic drugs that have been documented to reduce mortality in patients with VT or complex VA. Radiofrequency catheter ablation of VT has been beneficial in treating selected patients with arrhythmogenic foci of monomorphic VT. The automatic implantable cardioverter-defibrillator (AICD) is the most effective treatment for patients with life-threatening VT or ventricular fibrillation. Patients with AICDs should be treated with biventricular pacing, not with dual-chamber rate-responsive pacing at a rate of 70/min. Patients with AICDs should also be treated with beta-blockers, statins, and angiotensin-converting enzyme inhibitors or angiotensin blockers.

Acebutolol: Ventricular Tachycardia

This Hospital Pharmacy feature is extracted from Off-Label Drug Facts, a quarterly publication available from Wolters Kluwer Health. Off-Label Drug Facts is a practitioner-oriented resource for information about specific drug uses that are unapproved by the US Food and Drug Administration. This new guide to the literature enables the health care professional or clinician to quickly identify published studies on off-label uses and determine if a specific use is rational in a patient care scenario. A summary of the most relevant data is provided, including background, study design, patient population, dosage information, therapy duration, results, safety, and therapeutic considerations. References direct the reader to the full literature for more comprehensive information before patient care decisions are made. Direct questions or comments regarding Off-Label Drug Uses to hospital pharmacy@drugfacts.com .

Management of the older person with ventricular arrhythmias

OBJECTIVE

To review the prognosis and management of ventricular arrhythmias (VA) in persons with and without heart disease, with emphasis on older adults.

DATA SOURCES

A computer-assisted search of the English language literature (MEDLINE database) followed by a manual search of the bibliographies of pertinent articles.

STUDY SELECTION

Studies on the prognosis and management of VA in persons with and without heart disease were screened for review. Studies in older persons and recent studies were emphasized.

DATA EXTRACTION

Pertinent data were extracted from the reviewed articles. Emphasis was placed on studies involving older persons. Relevant articles were reviewed in depth.

DATA SYNTHESIS

Available data on the prognosis and management of VA in persons with and without heart disease, with emphasis on studies in older persons, were summarized.

CONCLUSIONS

Ventricular arrhythmias in older persons without heart disease should not be treated with antiarrhythmic drugs, nor should Class I antiarrhythmic drugs be used to treat VA in older persons with heart disease. Beta-blockers should be used to treat complex VA in older persons with ischemic or nonischemic heart disease without contraindications to beta-blockers. Amiodarone should be reserved for life-threatening ventricular tachyarrhythmias in older persons who cannot tolerate or who do not respond to beta-blockers. Angiotensin-converting enzyme inhibitors should be used to treat older persons with heart failure, an anterior myocardial infarction, or a left ventricular ejection fraction < or = 40%. If older persons have life-threatening recurrent ventricular tachycardia (VT) or ventricular fibrillation (VF) resistant to antiarrhythmic drugs, invasive intervention should be performed. The automatic implantable cardioverter-defibrillator is recommended in older persons who have medically refractory sustained VT or VF.

Treatment of ventricular arrhythmias in older adults

OBJECTIVE

To review the prognosis and management of ventricular arrhythmias (VA) in persons with and without heart disease with emphasis on older adults.

DATA SOURCES

A computer-assisted search of the English language literature (MEDLINE database) followed by a manual search of the bibliographies of pertinent articles.

STUDY SELECTION

Studies on the prognosis and management of VA in persons with and without heart disease were screened for review. Studies in older people and recent studies were emphasized.

DATA EXTRACTION

Pertinent data were extracted from the reviewed articles. Emphasis was on studies involving the older persons. Relevant articles were reviewed in depth.

DATA SYNTHESIS

Available data about the prognosis and management of VA in persons with and without heart disease, with emphasis on studies involving older people, were summarized.

CONCLUSIONS

VA in older persons without heart disease should not be treated with antiarrhythmic drugs. Class I antiarrhythmic drugs should not be used to treat VA in older persons with heart disease. Beta blockers should be used to treat complex VA in older persons with ischemic or nonischemic heart disease if there are no contraindications to beta blocker therapy. The use of amiodarone in treating complex VA should be reserved for life-threatening ventricular tachyarrhythmias in older persons who cannot tolerate or who do not respond to beta blockers. VA associated with congestive heart failure should be treated with angiotensin converting enzyme inhibitors. If older patients have life-threatening recurrent ventricular tachycardia or ventricular fibrillation resistant to antiarrhythmic drugs, invasive intervention should be performed. The automatic implantable cardioverter-defibrillator is recommended in older patients who have medically refractory sustained ventricular tachycardia or ventricular fibrillation.

Newer antiarrhythmic drugs

The effective management of cardiac arrhythmias remains a major challenge in cardiovascular therapeutics. The management of arrhythmias encompasses a wide spectrum of supraventricular and ventricular tachyarrhythmias occurring in patients with various cardiac diagnoses and different degrees of myocardial dysfunction. A number of the newer antiarrhythmic drugs that have either recently been released or appear promising are reviewed in this article. Drugs are described with respect to their basic pharmacology, electrophysiologic actions, pharmacokinetics and metabolism, hemodynamics, antiarrhythmic effects, side effects, interactions, indications, and dosage.

Beta-adrenergic blockers

beta-Adrenergic blocking drugs have been available for several years to treat ischemic heart disease and other cardiovascular and noncardiovascular disorders. There are multiple drugs in this class with various pharmacodynamic and pharmacokinetic properties that may be important in specific clinical situations and in avoiding certain adverse reactions. These drugs have been shown to be efficacious in relieving anginal symptoms and prolonging exercise tolerance, in reducing high blood pressure, for treating various arrhythmias, in therapy of hypertrophic cardiomyopathy, and for prolonging life in many survivors of acute myocardial infarction.

Acebutolol: a review of its pharmacology, pharmacokinetics, clinical uses, and adverse effects

Acebutolol is a new hydrophilic, cardioselective beta-adrenergic-blocking agent that possesses partial agonist and membrane-stabilizing activities. In the treatment of mild to moderate essential hypertension, once-daily acebutolol as monotherapy provides effective control in a large majority of patients and produces a further reduction in blood pressure when used concomitantly with diuretics. Acebutolol is as effective as other beta-blocking agents, and in a large, double-blind, parallel study against propranolol was found to cause less reduction in heart rate, and fewer neurologic side effects and patient withdrawals due to adverse effects. Oral acebutolol is also effective in suppressing premature ventricular contractions, and in small numbers of patients generally beneficial results were obtained in supraventricular and ventricular arrhythmias with intravenous administration. These salutary effects are attributable to beta blockade. Controlled clinical trials documented the antianginal actions of oral acebutolol in chronic stable angina pectoris; its efficacy in this regard is comparable to that of other beta-blocking agents. The drug produces smaller decreases in heart rate and cardiac output and alterations in peripheral vascular hemodynamics than beta-blocking drugs without partial agonist activity, and because of its cardioselectivity, it may be used cautiously in patients with bronchospastic disease. Acebutolol has minimal metabolic effects and does not elevate levels of blood lipids during long-term therapy; high-density-lipoprotein cholesterol increased with acebutolol in a small number of patients.

Effect of intravenous and oral acebutolol in patients with bundle branch block

We studied the effect of intravenous (1 mg/kg) and oral (400 mg) acebutolol on atrioventricular conduction in 22 patients with idiopathic bundle branch block and 1 to 1 atrioventricular conduction. Seven patients had previously symptomatic complete heart block (Group 1) and 15 were asymptomatic with bundle branch block only (Group 2). Following intravenous acebutolol heart rate decreased 82 +/- 16 to 63 +/- 16/min (P less than 0.01), A-H interval lengthened 98 +/- 22 to 121 +/- 30 msec (P less than 0.005) and H-V time was prolonged 60 +/- 13 to 70 +/- 17 msec (P less than 0.02) in those with previous heart block. The corresponding changes in the patients with no previous block were 74 +/- 14 to 61 +/- 8/min (P less than 0.01), 90 +/- 17 to 109 +/- 22 msec (P less than 0.05) and 48 +/- 15 to 56 +/- 14 msec (P less than 0.01). There was no difference between the basal or induced changes between these two groups. After intravenous acebutolol infusion 2 of 6 patients with previous spontaneous heart block and none of those without previous heart block developed atrioventricular block distal to His. The induced block was temporary (less than 10 min) and corresponded to the time of peak plasma acebutolol levels. Temporary atrioventricular block followed oral acebutolol administration in 4/7 patients with previous spontaneous heart block and 0/14 in those without block. In patients with bundle branch block intravenous acebutolol prolonged H-V conduction times in 19/20 patients and intravenous and oral acebutolol induced A-V block in 4/7 patients with previous spontaneous block.(ABSTRACT TRUNCATED AT 250 WORDS)

Acebutolol for premature ventricular contractions: short- and long-term effects

The safety and efficacy of oral acebutolol therapy for the suppression of premature ventricular contractions (PVCs) were assessed in two clinical trials pooled for analysis. Thirty-two patients suffering from organic heart disease, who had experienced an average of greater than or equal to 10 PVCs/h (range 14 to 996 three times a day) on Holter monitoring during a 24-hour baseline study period, were given acebutolol (100 mg three times a day to 400 mg four times a day) over 4 weeks. Three patients were withdrawn from the study for administrative reasons, and four patients were excluded from the efficacy analysis. Of the 25 remaining patients (24 men, 1 woman; mean age 56 years, range 37 to 69), 18 (72%) experienced some reduction in PVCs from the second through the fourth week of therapy. Eleven patients (44%) experienced clinically significant reductions (greater than or equal to 75%) in PVCs. The onset of the antiarrhythmic effect of acebutolol was within 7 days of administration. Transient mild to moderate side effects were noted in eight patients. Significant correlations (p less than 0.001) were observed between the mean daily dose of acebutolol and (1) mean blood levels, (2) reduction in PVCs, and (3) reduction in resting heart rate. The average daily dose of acebutolol ranged from 304 to 1060 mg. In nine patients receiving acebutolol in a 12-month open-label extension, both efficacy and safety were maintained. This study confirms that oral acebutolol therapy in both safe and efficacious for suppressing PVCs in patients with organic heart disease.

Beta-blocking potency and electrophysiologic effects of acebutolol

The beta-blocking potency of three doses of acebutolol (100, 200, and 600 mg three times a day) has been compared to that of propranolol (30, 60, and 180 mg three times a day) in a double-blind crossover study in 10 healthy volunteers (seven men, three women). On the basis of reduction in resting and exercise heart rates, propranolol was three to four times more potent than acebutolol on a milligram-for-milligram basis. Plasma levels showed large interindividual variation for both agents. Plasma levels were weakly correlated with the degree of beta blockade for both acebutolol (r = 0.333, p less than 0.001) and propranolol (r = 0.381, p less than 0.01). Dose and percent beta blockade were more strongly correlated (propranolol, r = 0.503, p less than 0.001; acebutolol, r = 0.574, p less than 0.001). In 11 patients (10 men, one woman) with coronary artery disease, acebutolol at 1 mg/kg infused over 15 minutes decreased heart rate and slowed conduction, increased the refractoriness of the atrioventricular node without a significant change in the atrial refractoriness, and at plasma levels greater than or equal to 1000 ng/ml slowed His-Purkinje conduction. The comparative potency data suggest that the magnitude of the decrease in the resting and exercise-induced changes in heart rate and double product, in relation to dose of acebutolol, provides quantitative indices for judging adequacy by beta blockade in clinical therapeutics. The use of plasma drug levels, however, does not appear to be helpful in judging the adequacy of beta blockade.(ABSTRACT TRUNCATED AT 250 WORDS)

Acebutolol: ten years of experience

During 10 years of clinical use involving almost 3 million patient-years, acebutolol has become established as a remarkably safe and well-tolerated beta-blocking agent, effective in treating essential hypertension and cardiac arrhythmias. The existence of a long-lived active metabolite (diacetolol) confers a 24-hour duration of action, which permits effective use of a once-daily regimen, particularly for hypertension. Acebutolol has low lipid solubility and low protein binding; the former property reduces the risk of central side effects, and the latter means that displacement interactions with other drugs are unlikely. Because acebutolol and its metabolite normally have both renal and hepatic excretion pathways, an alternative pathway is available should either be compromised through disease. Acebutolol is cardioselective, and clinical use has borne out the low incidence of bronchospasm in patients with impaired lung function. The possession of intrinsic sympathomimetic activity (ISA) leads to only modest reductions in cardiac output, which in turn reduces the chance of excessive bradycardia and the likelihood of precipitating heart failure. A combination of selectivity and ISA may be responsible for the low incidence of tiredness and cold extremities observed with acebutolol compared with other beta blockers. The unique pharmacologic and pharmacokinetic profile of acebutolol confers several therapeutic advantages and may be responsible for the generally low level of side effects experienced in clinical use.

Comparison of the antiarrhythmic effects of acebutolol and propranolol in the treatment of ventricular arrhythmias

This study was designed to assess the relative antiarrhythmic activity of fixed doses of 2 beta-adrenergic blocking agents, propranolol and acebutolol, in a prospective double-blind crossover trial. Twenty-one patients who had at least 30 premature ventricular contractions (PVCs) per hour while receiving placebo were entered into the study. Ten patients were randomized to initially receive propranolol, 40 mg every 8 hours, and 11 were assigned to receive acebutolol, 300 mg every 8 hours. After 6 weeks of treatment, patients were weaned off medication for 1 week and then placed on placebo for 1 week. Eighteen patients were available and eligible for crossover to the alternative regimen for an additional 6 weeks. All 21 patients completed courses with propranolol and 17 completed courses with acebutolol. The mean number of PVCs per hour during placebo, propranolol and acebutolol treatment were 267, 87 and 119, respectively. Using paired t test statistics on observation differences, both propranolol and acebutolol significantly reduced the number of PVCs per hour compared with placebo, whereas similar analysis revealed no significant difference in the antiarrhythmic effect. However, with the current sample size the power of the test is too low for the latter conclusion to be stated with confidence. Side effects were mild and infrequent, requiring discontinuation of acebutolol in 2 patients and discontinuation of propranolol in 1. Thus, acebutolol is a safe and effective antiarrhythmic agent and compares favorably with propranolol.