Acebutolol in supraventricular arrhythmias

Atrial Fibrillation: The New Epidemic of the Ageing World

The prevalence of atrial fibrillation (AF) increases with age. As the population ages, the burden of AF increases. AF is associated with an increased incidence of mortality, stroke, and coronary events compared to sinus rhythm. AF with a rapid ventricular rate may cause a tachycardia-related cardiomyopathy. Immediate direct-current (DC) cardioversion should be performed in patients with AF and acute myocardial infarction, chest pain due to myocardial ischemia, hypotension, severe heart failure, or syncope. Intravenous beta blockers, diltiazem, or verapamil may be administered to reduce immediately a very rapid ventricular rate in AF. An oral beta blocker, verapamil, or diltiazem should be used in persons with AF if a fast ventricular rate occurs at rest or during exercise despite digoxin. Amiodarone may be used in selected patients with symptomatic life-threatening AF refractory to other drugs. Digoxin should not be used to treat patients with paroxysmal AF. Nondrug therapies should be performed in patients with symptomatic AF in whom a rapid ventricular rate cannot be slowed by drugs. Paroxysmal AF associated with the tachycardia-bradycardia syndrome should be treated with a permanent pacemaker in combination with drugs. A permanent pacemaker should be implanted in patients with AF and symptoms such as dizziness or syncope associated with ventricular pauses greater than 3 seconds which are not drug-induced. Elective DC cardioversion has a higher success rate and a lower incidence of cardiac adverse effects than does medical cardioversion in converting AF to sinus rhythm. Unless transesophageal echocardiography has shown no thrombus in the left atrial appendage before cardioversion, oral warfarin should be given for 3 weeks before elective DC or drug cardioversion of AF and continued for at least 4 weeks after maintenance of sinus rhythm. Many cardiologists prefer, especially in elderly patients , ventricular rate control plus warfarin rather than maintaining sinus rhythm with antiarrhythmic drugs. Patients with chronic or paroxysmal AF at high risk for stroke should be treated with long-term warfarin to achieve an International Normalized Ratio of 2.0 to 3.0. Patients with AF at low risk for stroke or with contraindications to warfarin should be treated with aspirin 325 mg daily.

Management of the older person with atrial fibrillation

Atrial fibrillation (AF) is associated with a higher incidence of mortality, stroke, and coronary events than is sinus rhythm. AF with a rapid ventricular rate may cause a tachycardia-related cardiomyopathy. Immediate direct-current (DC) cardioversion should be performed in patients with AF and acute myocardial infarction, chest pain due to myocardial ischemia, hypotension, severe heart failure, or syncope. Intravenous beta blockers, verapamil, or diltiazem may be given to slow immediately a very rapid ventricular rate in AF. An oral beta blocker, verapamil, or diltiazem should be used in persons with AF if a fast ventricular rate occurs at rest or during exercise despite digoxin. Amiodarone may be used in selected patients with symptomatic life-threatening AF refractory to other drugs. Nondrug therapies should be performed in patients with symptomatic AF in whom a rapid ventricular rate cannot be slowed by drugs. Paroxysmal AF associated with the tachycardia-bradycardia syndrome should be treated with a permanent pacemaker in combination with drugs. A permanent pacemaker should be implanted in patients with AF and with symptoms such as dizziness or syncope associated with ventricular pauses greater than 3 seconds that are not drug-induced. Elective DC cardioversion has a higher success rate and a lower incidence of cardiac adverse effects than does medical cardioversion in converting AF to sinus rhythm. Unless transesophageal echocardiography has shown no thrombus in the left atrial appendage before cardioversion, oral warfarin should be given for 3 weeks before elective DC or drug cardioversion of AF and should be continued for at least 4 weeks after maintenance of sinus rhythm. Many cardiologists prefer, especially in older persons, ventricular rate control plus warfarin rather than maintaining sinus rhythm with antiarrhythmic drugs. Digoxin should not be used to treat patients with paroxysmal AF. Patients with chronic or paroxysmal AF at high risk for stroke should be treated with long-term warfarin to achieve an International Normalized Ratio of 2.0 to 3.0. Patients with AF at low risk for stroke or with contraindications to warfarin should receive 325 mg of aspirin daily.

Atrial fibrillation

The prevalence and incidence of atrial fibrillation increase with age. Atrial fibrillation is associated with a higher incidence of coronary events, stroke, and mortality than sinus rhythm. A fast ventricular rate associated with atrial fibrillation may cause tachycardia-related cardiomyopathy. Management of atrial fibrillation includes treatment of underlying causes and precipitating factors. Immediate direct-current cardioversion should be performed in persons with atrial fibrillation associated with acute myocardial infarction, chest pain due to myocardial ischemia, hypotension, severe heart failure, or syncope. Intravenous beta-blockers, verapamil, or diltiazem may be used to immediately slow a fast ventricular rate associated with atrial fibrillation. An oral beta-blocker, verapamil, or diltiazem should be given to persons with atrial fibrillation if a rapid ventricular rate occurs a rest or during exercise despite digoxin. Amiodarone may be used in selected persons with symptomatic life-threatening atrial fibrillation refractory to other drug therapy. Nondrug therapies should be performed in persons with symptomatic atrial fibrillation in whom a rapid ventricular rate cannot be slowed by drug therapy. Paroxysmal atrial fibrillation associated with the tachycardia-bradycardia syndrome should be managed with a permanent pacemaker in combination with drugs. A permanent pacemaker should be implanted in persons with atrial fibrillation in whom symptoms such as dizziness or syncope associated with non-drug-induced ventricular pauses longer than 3 seconds develop. Elective direct-current cardioversion has a higher success rate and a lower incidence of cardiac adverse effects than medical cardioversion in converting atrial fibrillation to sinus rhythm. Unless transesophageal echocardiography shows no thrombus in the left atrial appendage before cardioversion, oral warfarin should be given for 3 weeks before elective direct-current or drug cardioversion of atrial fibrillation and continued for at least 4 weeks after maintenance of sinus rhythm. Many cardiologists prefer the treatment strategy of ventricular rate control plus warfarin rather than to maintain sinus rhythm with antiarrhythmic drugs, especially in older patients. Digoxin should not be used in persons with paroxysmal atrial fibrillation. Patients with chronic or paroxysmal atrial fibrillation who are at high risk for stroke should be treated with long-term warfarin to achieve an International Normalized Ratio (INR) of 2.0 to 3.0. Persons with atrial fibrillation who are at low risk for stroke or who have contraindications to warfarin should receive 325 mg aspirin daily.

Management of the older person with atrial fibrillation

OBJECTIVE

To review the management of the older person with atrial fibrillation (AF).

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 management of persons with AF were screened for review. Studies of persons older than age 60 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 about the management of persons with paroxysmal or chronic AF were summarized

CONCLUSIONS

Management of AF includes treatment of the underlying disease and precipitating factors. Immediate direct-current cardioversion should be performed in persons with AF associated with an acute myocardial infarction, chest pain caused by myocardial ischemia, hypotension, severe heart failure, or syncope. Intravenous verapamil, diltiazem, or beta-blockers should be used to slow a very rapid ventricular rate associated with AF immediately. Oral verapamil, diltiazem, or a beta-blocker should be given if a rapid ventricular rate occurs at rest or during exercise despite digoxin. Amiodarone may be used in selected persons with symptomatic life-threatening AF refractory to other drug therapy. Nondrug therapies should be performed in persons with symptomatic AF in whom a rapid ventricular rate cannot be slowed by drug therapy. Paroxysmal AF associated with the tachycardia-bradycardia syndrome should be treated with a permanent pacemaker in combination with drugs. A permanent pacemaker should be implanted in persons with AF who develop cerebral symptoms such as dizziness or syncope associated with ventricular pauses greater than 3 seconds that are not drug-induced. Elective cardioversion of AF should not be performed in asymptomatic older persons with chronic AF. Unless transesophageal echocardiography has shown no thrombus in the left atrial appendage before cardioversion, oral warfarin should be given for 3 weeks before elective direct-current or drug cardioversion of AF and continued for at least 4 weeks after maintenance of sinus rhythm. Many cardiologists prefer the treatment strategy, especially in older persons, of ventricular rate control plus warfarin rather than maintaining sinus rhythm with antiarrhythmic drugs. Digoxin should be avoided in persons with sinus rhythm who have a history of paroxysmal AF. Older persons with chronic or paroxysmal AF who are at high risk for stroke or who have a history of hypertension and no contraindications to warfarin should receive long-term warfarin to achieve an International Normalized Ratio of 2.0 to 3.0. Older persons with AF who are at low risk for stroke or who have contraindications to warfarin should receive 325 mg of aspirin daily.

Intravenous esmolol for the treatment of supraventricular tachyarrhythmia: results of a multicenter, baseline-controlled safety and efficacy study in 160 patients. The Esmolol Research Group

Efficacy and safety of esmolol in the treatment of supraventricular tachyarrhythmias (SVT) was evaluated in this open-label, baseline-controlled, multicenter study. One hundred sixty patients with SVT received an intravenous infusion of esmolol in doses ranging from 25 to 300 micrograms/kg/min for up to 24 hours. All of the 160 patients were evaluated for safety, and 147 of them were eligible for evaluation of therapeutic response. Therapeutic response was defined as greater than or equal to 15% reduction in the average baseline heart rate of conversion to normal sinus rhythm. Seventy-nine percent (116 of 147) of the patients exhibited a therapeutic response. The cumulative percentage response increased significantly with increasing esmolol doses up to 200 micrograms/kg/min. The mean (+/- SEM) dose of esmolol producing a therapeutic response was 97.2 +/- 5.5 micrograms/kg/min. Among all patients (n = 160), 39% exhibited hypotension. In 58% of these patients, hypotension resolved with or without adjustment of the esmolol dose while the infusion continued; among almost all of the remaining patients, hypotension resolved within 30 minutes after esmolol was discontinued. Most patients at risk for adverse effects during beta blockade (i.e., those with diabetes mellitus, congestive heart failure, asthma, etc.) tolerated esmolol therapy, and there were no clinically important trends among the reported changes in laboratory variables. The results of the study indicate that esmolol is effective and well tolerated for the treatment of SVT.

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.

Comparison of acebutolol with propranolol, quinidine, and placebo: results of three multicenter arrhythmia trials

Acebutolol was compared to placebo, propranolol, and quinidine for the suppression of chronic ventricular arrhythmia in three double-blind, randomized crossover studies. Patients averaged greater than or equal to 10 to 30 premature ventricular contractions (PVCs) per hour in the baseline periods. Compared to baseline in all three studies, acebutolol significantly (p less than 0.002 to p less than 0.001) reduced mean total PVCs and complex PVCs. In all measurements, acebutolol was superior to placebo (p less than 0.02 to p less than 0.001) and comparable to propranolol and quinidine. During acebutolol treatment, 39% of the patients had reductions of greater than or equal to 75% in mean hourly PVC frequency compared to 23% during placebo treatment (p = 0.02). Similar numbers of patients had greater than or equal to 75% reductions during acebutolol treatment in comparison with propranolol and quinidine. Acebutolol was better tolerated than quinidine and produced an antiarrhythmic effect equivalent to that of propranolol, with a significantly (p less than 0.01) lesser decrease in resting heart rate. The antiarrhythmic activity of acebutolol, its ancillary pharmacologic properties, and its tolerance by a diverse group of patients make acebutolol a significant tool for the clinician in the management of chronic arrhythmia.

Comparison of acebutolol and propranolol therapy for ventricular arrhythmias

The effects of acebutolol, a new investigational cardioselective beta blocker, and propranolol on ventricular arrhythmias were compared in 14 patients with more than 30 premature ventricular contractions (PVCs) per hour. Each patient served as their own control, receiving both drugs and placebo in random sequence and in double-blind fashion, with an intervening one-week, drug-free period. Each drug was given for a two-month period, the maximum acebutolol dosage reaching 600 mg tid and the maximum propranolol dosage 80 mg tid. Seventy-two-hour ambulatory electrocardiographic monitoring assessed arrhythmia frequency for each study period. Mean PVC counts did not significantly differ during the two control periods. Acebutolol decreased mean PVC count by 65% (P less than .02), with eight patients exhibiting a 70% or greater decrease. Only three patients exhibited a similar decline with propranolol. The incidence of PVCs was not significantly decreased by propranolol. Acebutolol reduced the number of couplets by 70% (P less than .04), whereas propranolol did not significantly affect couplets. At the dosage of 600 mg tid, acebutolol was well tolerated, effectively suppressed total PVCs and couplets, and appeared to be more effective than propranolol administered at 80 mg tid.

Effects of acebutolol on paroxysmal atrioventricular reentrant tachycardia in patients with manifest or concealed accessory pathways

Electrophysiologic studies before and after administration of 50 mg of intravenous (IV) acebutolol were performed in 20 patients. Four of the 20 had persistent preexcitation, two had intermittent preexcitation, and 14 had a concealed retrogradely conducting accessory pathway (AP). Acebutolol depressed anterograde AP conduction with loss of preexcitation in one patient and increased the effective refractory period of AP in the remaining three; in most, it depressed anterograde normal pathway conduction. The longest atrial paced cycle length producing atrioventricular (AV) nodal block increased from 290 +/- 7 to 39 +/- 6 msec (mean +/- SEM) after acebutolol (p less than 0.01). Acebutolol had no significant effect on retrograde AP conduction. Sustained AV reentrant tachycardia was inducible in all 20 patients before acebutolol and in 19 after acebutolol. The cycle length of tachycardia increased from 323 +/- 8 to 352 +/- 8 msec after acebutolol (p less than 0.01), reflecting an increment of A-H interval from 148 +/- 8 to 174 +/- 9 msec (p less than 0.01). Electrophysiologic studies were reported after 800 mg of oral acebutolol given in four divided doses at six-hour intervals in eight patients. The results were comparable to those of IV acebutolol. Thus, acebutolol depresses AV nodal conduction and slows the rate of AV reentrant tachycardia, but is generally ineffective in inhibiting the induction of sustained tachycardia. It occasionally depresses anterograde AP conduction.

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

The safety and efficacy of acebutolol in suppressing ventricular ectopy was evaluated in 60 males (average 59 years) using 24-hour Holter recordings and a double-blind, randomized, crossover protocol. Acebutolol, 200 mg and 400 mg thrice daily, was compared with placebo. Only patients who had a mean of at least 30 ventricular premature complexes (VPCs) per hour on three 24-hour control Holter recordings were included. Analysis of Holter recordings revealed greater than 70% reduction in VPCs/hour from control levels during acebutolol therapy in over 50% of the 60 patients; dose-related reduction in the mean number of single and paired VPCs and ventricular tachycardia episodes (p less than 0.05) by acebutolol; and significant, asymptomatic reduction in resting heart rate and blood pressure. All side effects were transient. Acebutolol was discontinued because of side effects in one patient only.

Variability of spontaneous and exercise-induced ventricular arrhythmias in the absence and presence of treatment with acebutolol or quinidine

A randomized double-blind crossover trial was undertaken in 20 volunteers to evaluate the effects of acebutolol and sustained release quinidine sulfate. The patients had an average of 10 or more premature ventricular complexes/hour on two 24 hour electrocardiographic recordings, or 10 or more/min during two cycle stress tests, or any number of complex forms of ventricular ectopic activity on either test. The 24 hour recordings yielded greater detection of complex forms than did stress tests and manifested similar relative variability in frequency of ventricular ectopic beats. The extent of variability from hour to hour within the 24 hour monitoring periods tended to have an increasing relation with frequency of ectopic beat activity regardless of the presence or absence of treatment. Within-patient variability among periods with equivalent treatment status also tended to have such an increasing relation with frequency of ectopic beat activity. About 35 percent of the variation was among subjects, 20 percent among months within subjects, 20 percent among days in months and 25 percent among hours in days. Acebutolol, 300 mg three times daily, produced effective beta receptor blockade and was better tolerated than sustained release quinidine sulfate in identical doses and had equal suppressant effects. The results of the variability studies provide guidelines for the design of adequate clinical trials testing suppressant interventions.