Heart Disease/Diabetes

Some drugs provide better control of heart rate for patients with atrial fibrillation at both rest and exercise

The goal of therapy for adults suffering from atrial fibrillation (abnormally fast heart rate) is to control their rapid heartbeat. If the heart continues to beat out of control, it can worsen congestive heart failure, myocardial ischemia, or breathlessness and palpitations.

Drugs that are effective for heart rate control at rest may not be effective during exercise, concludes a study by researchers at the Evidence-based Practice Center at Johns Hopkins University, which is supported by the Agency for Healthcare Research and Quality (Contract 290-97-0006). They reviewed 45 randomized controlled trials published before May 1998, which evaluated 17 drugs used for heart rate control in adults with non-postoperative atrial fibrillation.

The researchers found that the nondihydropyridine calcium-channel blockers, diltiazem and verapamil, worked best for heart rate control at rest and with exercise, since these drugs do not decrease exercise tolerance. Selected beta-blockers such as nadolol or second-generation beta-antagonists such as atenolol and metoprolol also are efficacious at rest and with exercise. There is some evidence, however, that beta-blockers cause a transient decrease in exercise tolerance. For patients unlikely to exercise, such as those incapacitated by other illness, digoxin should provide acceptable heart rate control at rest.

Trials evaluating other drugs yielded little evidence to support their use, but they may yet be promising, according to the researchers. They expect, for example, that the third-generation beta-blockers such as carvedilol will be effective in heart rate control, with an improvement in exercise tolerance. Both heart rate control and exercise tolerance affect the mortality and well-being of patients with atrial fibrillation, including their ability to conduct their daily lives.

More details are in "The evidence regarding the drugs used for ventricular rate control," by Jodi B. Segal, M.D., M.P.H., Robert L. McNamara, M.D., M.H.S., Marlene R. Miller, M.D., and others in the January 2000 Journal of Family Practice 49(1), pp. 47-59.

Editor's Note: The report from which these findings are drawn, Management of New Onset Atrial Fibrillation, Evidence Report/Technology Assessment No. 12 (AHRQ Publication No. 00-E007), is expected to be available from AHRQ by fall 2000. A summary of the report (AHRQ Publication No. 00-E006) is available from the AHRQ Publications Clearinghouse.

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