Beta blokerler bazı hastalarda etkili değil. (İng)

Study: Beta blockers may not be effective in some patients

(Ref: Forbes, JAMA, ABC News, Chicago Tribune, U.S. News & World)

October 3rd, 2012

By: Matthew Dennis

• Results of an observational study published Wednesday in JAMA suggest that beta blockers may not prevent myocardial infarction (MI), stroke or death, and may instead raise the risk of death or hospitalisation for atherothrombotic events or a revascularisation procedure in some patients. “A lot of physicians still prescribe beta blockers, especially in patients who have known [coronary artery disease (CAD)],” noted lead author Sripal Bangalore, adding that “we need clinical trials to say which are the patients who would benefit from beta blockers.”

The study looked at 44 708 patients enrolled in the REACH registry, 31 percent of whom had a prior MI, 27 percent of whom had documented CAD without MI, and 42 percent of whom only had a risk factor for CAD. The primary outcome of the study, which had a median follow-up of 44 months, was a composite of cardiovascular death, non-fatal MI, or non-fatal stroke. The secondary measure was the primary outcome plus hospitalisation for atherothrombotic events or a revascularisation procedure.

Results showed that in the group of patients who had suffered a prior MI, event rates for both outcome measures weren’t significantly different among those treated with beta blockers compared to those who hadn’t received the drugs. In people with CAD without an MI, the researchers noted that event rates were not different in those with beta blocker use compared to those without for the primary outcome. However, for the secondary measure, event rates were 30.6 percent in those taking beta blockers, versus 27.9 percent among those not taking the drugs.

Further data indicated that in patients who only had a risk factor for coronary artery disease, the event rates were higher in those given beta blockers compared to those not taking the drugs for the primary outcome, at 14.2 percent and 12.1 percent, respectively, and for the secondary outcome, at 22 percent and 20.2 percent, respectively, but not for MI or stroke. The researchers also found that among patients with an MI in the last year, use of beta blockers was associated with a lower incidence for the secondary measure.

Bangalore suggested that the increased risks seen for some patients may be due in part to the nature of beta blockers themselves. He noted that beta blockers are less effective than other hypertension drugs and are not considered first-line treatment. In addition, beta blockers increase the risk of diabetes and increase cholesterol levels, Bangalore said, adding that “the combination of all these may be responsible for the worse outcomes.”

Commenting on the results, American Heart Association spokesman Gregg Fonarow remarked that the study “was not designed to evaluate the role of beta blockers and vital data including blood pressure, heart rate, contraindications and intolerance to beta blockers.” He added that “specific agent [beta blocker] and dose were not available and could not be adjusted for,” and “as a result of these limitations, these findings add little to the current evidence.”