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Beta blockers reduce risk of heart attack, increase stroke risk, large-scale study confirms

by Colin Poitras - November 17, 2008

In one of the most stringent studies to date of the popular blood pressure-lowering drugs known as beta blockers, researchers at the UConn/Hartford Hospital Evidence-based Practice Center have confirmed that these drugs reduce the chances of a heart attack following non-cardiac surgery but increase the risk of having a stroke.

The findings were presented at the American Heart Association’s 2008 Scientific Sessions research conference in New Orleans Nov. 10 and were featured in a special “Best of Scientific Sessions” webcast highlighting the latest advancements in the diagnosis, treatment, and prevention of cardiovascular disease and stroke.

Ripple Talati, an adjunct assistant professor of pharmacy and a cardiovascular pharmacology and outcomes fellow, authored the study.

She was joined by adjunct assistant professor and cardiac pharmacology fellow Kurt Reinhart; the practice center’s director and pharmacy professor C. Michael White, and assistant professor of pharmacy practice Craig Coleman, who also serves as the center’s methods chief. Drs. Art Sedrakyan, task order officer for the Agency for Healthcare Research and Quality, and Jeffrey Kluger, the center’s associate director, also served as co-authors of the report.

The findings were based on a stringent analysis of six clinical trials involving more than 10,000 patients worldwide who participated in random, double-blind trials and who had never taken a beta blocker before.

The study found that beta blockers reduced the odds of a patient having a heart attack by 26 percent but nearly doubled the chances of a patient having a stroke.

People deemed at high risk of stroke before major surgery showed little additional risk from taking beta blockers, while patients considered at low risk of stroke significantly increased their risk, the study said. The study also showed beta blockers significantly increased some patients’ likelihood of having problems with low blood pressure or low heart rate following surgery.

While the researchers caution that more studies are needed to evaluate the underlying cause of the findings, they urge physicians and patients to use caution when considering using beta blockers.

“If our study estimates are accurate, then one patient in 200 will have a stroke from the use of beta blockers in order to prevent one patient in 72 from having a heart attack,” Talati says.

“As such, future research is a necessity, and doctors and patients should be cautious.”

The use of beta blockers after non-cardiac surgery has been the subject of much debate. Such surgery often puts stress on the heart, increasing its demand for oxygen.

Beta blockers help minimize the effects of the stress hormone catecholamine, thereby lowering blood pressure and heart rate and reducing strain on the heart.

While other studies have shown that beta blockers have the potential to both reduce the chance of heart attack and increase the risk of death or stroke, the UConn analysis was more stringent than most and included study data that only recently became available.

The researchers found that 4.1 percent of patients taking beta blockers died after surgery, compared to 3.5 percent of patients given a placebo.

Of those suffering a heart attack, the researchers found that 4 percent of people on beta blockers experienced a heart attack, compared to 5.4 percent of people who were given a placebo.

In evaluating the risk of stroke, the researchers found that 1 percent of patients who received a beta blocker experienced a stroke, compared to 0.5 percent of patients who received a placebo, indicating a two-fold increase in the odds of developing a stroke when a patient was taking beta blockers.

Robert McCarthy, dean of the School of Pharmacy, says the study highlights the importance of the University’s new evidence-based practice center, which was established last year through a five-year, up to $5 million contract with the Agency for Healthcare Research and Quality.

It is one of only 14 such centers in North America and the first awarded to a college of pharmacy.

The UConn/Hartford Hospital center focuses on pharmacy practice and evaluates different drug therapies, especially those that are common, expensive, and/or significant to Medicare and Medicaid patients.

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