BMJ: New data for ARB positive, but still a mixed-bag

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Adding to the conflicting body of evidence surrounding angiotensin receptor blockers (ARBs), research published last week in the British Medical Journal contradicted previous evidence that outlined that ARBs may increase a patient’s risk for MI.  Researchers instead found that use of the drugs decreased the risk of stroke, heart failure and the onset of diabetes.

Recent evidence centering on ARBs have shown both risks and benefits to using this drug class. While an analysis published in Lancet Oncology back in June showed that ARB use was potentially linked to cancer, another published in a 2008 issue of the Journal of Hypertension showed that ARBs may be superior to ACE inhibitors in preventing stroke. While unverified, these data leave clinicians asking whether the benefits outweigh the risks.

However, in the most recent BMJ study, researchers evaluated the cardiovascular outcomes associated with ARB use. To do so, Sripal Bangalore, MD, of the New York University School of Medicine in New York City, and colleagues conducted a review of previous randomized controlled trials (RCTs) that compared ARB outcomes with placebo. They evaluated 37 RCTs that included 147,020 patients, and assessed the CV risk and possible increased risk for MI when ARBs were administered.

Of the studies, 17 compared ARBs with placebo and 22 compared ARBs with active treatments. Of the 147,020 patients, 49.8 percent were randomized to receive ARBs while 50.2 percent were randomized to controls. The average follow-up of the trials was 3.3 years.

The researchers reported that ARB usage was not associated with an increased risk of MI when compared to the controls, and said that results were similar when ARBs were compared with placebo or active treatments. Additionally, Bangalore et al said that ARBs were also not associated with any increased risk of all-cause death, CV death or angina.

ARBs were however, found to be linked to a 10 percent reduction in the risk of stroke, 13 percent reduction in the risk of HF and a 15 percent reduction in risk of diabetes compared with the control groups.

“In this meta-analysis we found no evidence to support the theory that angiotensin receptor blockers increase the risk of myocardial infarction,” the authors wrote. “Our meta-analysis showed firm evidence of a lack of significant effect of angiotensin receptor blockers on myocardial infarction, ruling out even a 0.3 percent (number need to harm >333) absolute increase in the risk of myocardial infarction with angiotensin receptor blockers.”

The authors stated that the analyses could not however rule out a <0.3 percent absolute increase of MI with ARBs, but deemed this “clinically less important.”

It was determined that there was no detected benefit for the outcome of MI or CV mortality and that ARBs were just as effective as active treatments in terms of outcomes. “Thus angiotensin receptor blockers, unlike angiotensin converting enzyme inhibitors seem not to have any special “cardioprotective” effects, even when compared with placebo.”

However, the researchers did find that compared with placebo and active treatments, ARBs reduced the risk of stroke.

Researchers concluded: “While the results from our sensitivity analysis were largely similar, the risk reduction in trials at low risk of bias was smaller in magnitude, although significant. Thus, the risk reduction for the outcomes of stroke, heart failure, and new onset diabetes with angiotensin receptor blockers is modest.”