A class of drugs once widely used to lower blood pressure - beta-blockers - may actually lead to heart problems, a study concludes.

Beta-blockers work by slowing the heart rate, thereby reducing blood pressure. Heart rate lowering with beta-blockers has been shown to have beneficial effects in people who’ve had a heart attack or who have heart failure, but findings from a new review indicate that this is not the case for patients with hypertension.

Dr. Franz H. Messerli, from Columbia University in New York, and colleagues looked at 22 relevant clinical trials involving patients treated for high blood pressure, and selected nine trials that included heart rate data.

As reported in the Journal of the American College of Cardiology, all told, 34,096 patients were given beta-blockers, 30,139 received other blood pressure-lowering agents, and 3987 got an inactive “placebo.”

Participants treated with beta-blockers achieved lower heart rates than did other patients. However, heart rate lowering with beta-blockers increased the risks of dying and of having a heart attack or stroke, and developing heart failure. Moreover, the slower the heart rate, the greater the risk of these events.

In an accompanying editorial, Dr. Norman M. Kaplan, from the University of Texas Southwestern Medical Center in Dallas, comments that the research “adds another post-mortem explanation for the fall of beta-blockers, showing higher mortality associated with the slower heart rate they induce.”

He adds that beta-blockers will remain appropriate for treating for heart failure, for after a heart attack, and for slowing excessive heart rates, “but no longer for hypertension in the absence of these compelling indications.”

SOURCE: Journal of the American College of Cardiology, October 28 2008.