JACC in a Flash | Although the ACC/AHA guidelines gave beta-blockers for secondary prevention in patients with ST-segment elevation myocardial infarction (STEMI) a class I designation, the evidence for this recommendation predates the era of reperfusion. Currently, there is little evidence about benefits of longterm beta-blocker therapy on clinical outcomes in STEMI patients after primary PCI.

"Although outcomes of patients with MI have greatly improved after the introduction of primary PCI, opti-mal medical therapy after successful reperfusion in patients with STEMI is very important," Jeong Hoon Yang, MD, and colleagues wrote in a study appearing in JACC Cardiovascular Interventions, and results from their study suggest that beta-blockers might fill that role.

Using data from a nationwide, prospective, multicenter registry series dedicated to MI, Yang et al. examined outcomes among 8,510 STEMI patients undergoing primary PCI: 6,873 (80.8%) who were prescribed beta-blockers at discharge and 1,637 (19.2%) who were not. The investigators noted that patients in the no-beta-blocker group were higher-risk subjects; they were older and had a higher prevalence of prior MI, low left ventricular ejection fraction, and post-procedural TIMI flow of 0-1, and were also less likely to receive aspirin, clopidogrel, statins, or PCI with a stent.

During the median follow-up of 367 days, all-cause death occurred in 205 patients, with a significantly lower incidence of this primary endpoint in the beta-blocker group (2.1% vs. 3.6% in the no-beta-blocker group; p < 0.001). The combined endpoint of all-cause death or MI also occurred less frequently in the beta-blocker group, while both groups had comparable incidences of MI, any coronary revascularization, and rates of major adverse cardiac events (MACE; TABLE).

Dr. Yang and colleagues found similar associations in a propensitymatched population of 1,325 patient triplets: beta-blocker therapy was associated with a lower incidence of allcause death (2.8% vs. 4.1%; adjusted HR = 0.46; 95% CI 0.27-0.78; p = 0.004), as well as cardiac death (1.5% vs. 2.8%; adjusted HR = 0.39; 95% CI 0.19-0.79; p = 0.01). Beta-blocker use did not produce a difference in rates of MI, any coronary revascularization, and MACE.

"It is uncertain why there were no significant differences between the groups in the incidences of MI and revascularization," the investigators noted. Potential reasons for this weak association include: unrestricted use of drug-eluting stents, complete revascularization, and medication other than beta-blockers (such as statins, renin angiotensin system blockers, or dual antiplatelet therapy). Looking at what was likely to predict all-cause death, older age, left anterior descending artery as the infarct-related artery, and no beta-blocker use at discharge were the most common factors (in other words, the factors that made the no-beta-blocker group "high risk").

In a subgroup analysis, the investigators also found that the outcomes according to beta-blocker therapy observed in the overall population were consistent in complex subgroups, including patients with a relatively low-risk profile such as left ventricular ejection fraction >40% or single-vessel disease. Importantly, they added, the association with better outcome of beta-blocker therapy was consistent across both high- and low-risk profile patients. "Although the findings are hypothesis-generating, our results support the current ACC/AHA guidelines, which recommend long-term beta-blocker therapy in all patients with STEMI regardless of risk profile," Dr. Yang and colleagues concluded.

Yang JH, Hahn J-Y, Song YB, et al. JACC Cardiovasc Interv. 2014;7:592-601.

Keywords: CardioSource WorldNews Interventions

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