Beta-blocker Therapy Seems to Boost Post-PCI Outcomes in Patients With ACS

Patients with ACS undergoing PCI have a lower risk of all-cause mortality in the first year when they receive beta-blockers at discharge, a Chinese registry study suggests.

Moreover, the benefits appear to be greatest in patients with NSTEMI rather than unstable angina or STEMI and in those receiving lower doses, Chenze Li, MD (Huazhong University of Science and Technology, Wuhan, China), and colleagues report in a study published online November 16, 2016, ahead of print in the Journal of the American Heart Association.

“However, further exploration of the clinical usefulness of beta-blocker therapy in patients with ACS warrants large-scale clinical trials,” they write.

Jeffrey Goldberger, MD (University of Miami, FL), agreed on the need for further research in this area when commenting on the study for TCTMD. He noted that the major beta-blocker trials were performed in the 1970s and 1980s, mostly in patients with STEMI. Those findings were later extended to NSTEMI but there are limited data on the effect of beta-blockers in patients with unstable angina, he said.

In the contemporary era, Goldberger added, there are questions about whether beta-blockers should still be a mainstay of therapy. “For a lot of years this has been sort of a dormant area of research . . . and it really became dogma that patients should be treated with beta-blockers after MI. But I think that a lot of these studies now are reinvigorating the need for further research to answer these critically important questions.”

Benefits Confined to NSTEMI?

Guidelines from the American College of Cardiology and American Heart Association recommend using beta-blockers in patients with STEMI and NSTEMI, although studies looking at the effects of treatment have provided somewhat mixed results.

To explore the issue, the investigators turned to a prospective registry of patients with ACS undergoing PCI at Tongji Hospital in Wuhan. The analysis included 3,180 patients treated between March 1, 2009, and December 30, 2014; 76.2% were discharged on beta-blockers.

Those who received the therapy had a lower rate of all-cause mortality (primary endpoint) through 1 year of follow-up (0.7% vs 2.1%; unadjusted HR 0.33; 95% CI 0.17-0.65). The difference remained significant in adjusted and propensity-matched analyses.

After adjustment, however, discharge beta-blockers were not associated with a lower risk of a composite of all-cause death, nonfatal MI, heart failure readmission, and cardiogenic hospitalization.

The researchers then performed a post hoc analysis by ACS type, and found that in the NSTEMI subgroup, beta-blocker therapy was tied to a lower risk of all-cause mortality (0.2% vs 6.4%; unadjusted HR 0.04; 95% CI 0.00-0.27), a finding that remained consistent after adjustment. Similar benefits were not seen in patients with unstable angina or STEMI, although the authors note that the study lacked statistical power to demonstrate differences in those groups.

Another analysis showed that beta-blocker therapy at less than 50% of the target dose was associated with a lower risk of all-cause mortality compared with no beta-blockers (adjusted HR 0.40; 95% CI 0.19-0.82), but using the drugs at 50% or more of the target dose was not (adjusted HR 0.46; 95% CI 0.13-1.59).

Tools to Guide Dosing Needed

Goldberger pointed out that the finding that lower doses of beta-blockers were at least as good as higher doses was similar to the result from the OBTAIN registry, for which he was the principal investigator.

There are many possible reasons to explain that, he said. For instance, recent evidence suggests that significant bradyarrhythmias are relatively frequent after MI, and those would be worsened by higher versus lower doses of beta-blockers, he said.

 The study “really does open up the question of who should be treated with beta-blockers and what the proper dose is,” Goldberger said. “My personal opinion is that there’s no reason to believe that there’s one right dose for every single patient.”

Some might fare better with lower doses, and others might benefit from higher doses, he added, “but right now we don’t have the right tools to be able to decide which patients need to be on which doses.”

Thus, he said, this is an area that requires renewed attention. The findings of the current study “are intriguing,” he said. “ I don’t think they’re ready to cause us to alter current practice but I think they’re certainly strong enough to raise questions about our current practice and help us hopefully launch the right studies to really figure it out.”