October 2nd, 2012

Registry Study Raises Questions About Cardioprotective Effect of Beta-Blockers

Although beta-blockers have been a cornerstone of therapy for patients with coronary artery disease for more than a generation, a new study in JAMA suggests that that in the modern era, beta-blockers might not improve outcomes.

Sriapl Bangalore and colleagues analyzed data from 44,708 patients enrolled in the Reduction of Atherothrombosis for Continued Health (REACH registry), of whom 31% had a prior MI, 27% had documented CAD without MI, and 42% had CAD risk factors only. Patients who received beta-blockers were compared with matched controls and were followed for a median of 44 months.

Beta-blocker use was not associated with a significant reduction in the rate of cardiovascular death, nonfatal MI, or nonfatal stroke. Here are the rates:

Among CAD patients with prior MI:

  • 16.93% in the beta-blocker group versus 18.60% in the controls, hazard ratio [HR] 0.90, CI 0.79-1.03, p=0.14

CAD patients without prior MI:

  • 12.94% versus 13.55%, HR 0.92, CI 0.79-1.08, p=0.31

Patients with risk factors only:

  • 14.22% versus 12.11%, HR 1.18, CI 1.02-1.36, p=0.02

In their paper, the REACH investigators point out that the evidence supporting beta-blocker use after MI is now quite old, with most of the trials having been performed prior to the widespread use of modern reperfusion strategies and medical therapy. The presumed “cardioprotective” effect of beta-blockers in patients without MI did not have an evidence base and was an extrapolation from heart failure trials and older post-MI trials. On the other hand, they note, there is evidence to support the use of beta-blockers in acute MI patients without shock or heart block.

Although the finding may be surprising to some clinicians, the results are consistent with recent guidelines, the authors note. In the AHA secondary prevention guidelines, beta-blockers receive a class I recommendation for heart failure, MI, or ACS for up to 3 years after MI but only a IIa recommendation for longer-term therapy. For other patients, beta blockers receive a class IIb recommendation.

For a CardioExchange Q&A with the study’s author – and to share your own comments about the study – see here.

One Response to “Registry Study Raises Questions About Cardioprotective Effect of Beta-Blockers”

  1. A key point here, that should not be lost, is that this study generally supports the current guidelines. Their results suggest that BB at least for the year after MI is beneficial – and continue to raise questions about its utility for secondary prevention in patients with CAD. It also raises questions about how long after MI it might be useful to treat with BB. The study is not really relevant to current recommendations about patients with heart failure. An important issue is that we need more contemporary info about the usefulness of beta-blockers.