急性心肌梗死(AMI)後患者應用β受體阻滯劑治療可改善生存，而在臨床實踐中，β受體阻滯劑的劑量常比在隨機試驗中使用的劑量低。較大劑量的β受體阻滯劑是否可增加AMI患者的生存率?對此美國學者們開展了一項多中心注冊研究，結果表明，與較小劑量的β受體阻滯劑相比，使用既往隨機臨床試驗中類似劑量的β受體阻滯劑並不增加患者的生存率。相關研究論文近期在線發表於《美國心髒病學會雜誌》(J Am Coll Cardiol.)

該研究納入了7057例AMI連續患者，根據在隨機臨床試驗中使用的目標β阻滯劑劑量索引出院β阻滯劑劑量，將患者分為以下四組：0%-12.5%，12.5%-25%，25%-50%，>50%。主要終點事件為至死亡時間，用多變量和傾向評分分析組間差異。

結果顯示，共有6682例患者完成隨訪，中位隨訪2.1年，91.5%出院後使用β阻滯劑(平均劑量為目標劑量的38.1%)。與未使用β阻滯劑者相比，使用所有劑量β阻滯劑組患者的死亡率較低(P< 0.0002)。

校正多變量後，與>50%目標劑量組相比，0%-12.5%、12.5%-25%和25%-50%目標劑量組的2年死亡率危險比分別為0.862、0.799、0.963。多變量分析的擴展協變量和傾向得分分析也顯示，較大劑量的β阻滯劑與較好預後無關。

英文：Effect of Beta-Blocker Dose on Survival After Acute Myocardial Infarction

Commentary by Dr. Valentin Fuster

Jeffrey J. Goldberger, MD, MBA∗; Robert O. Bonow, MD∗; Michael Cuffe, MD†; Lei Liu, PhD‡; Yves Rosenberg, MD, MPH§; Prediman K. Shah, MD‖; Sidney C. Smith, Jr., MD¶; Haris Subačius, MA∗

[-] Author Information

∗ Center for Cardiovascular Innovation and the Division of Cardiology, Feinberg School of Medicine, Northwestern University, Chicago, Illinois

Abstract

Background Beta-blocker therapy after acute myocardial infarction (MI) improves survival. Beta-blocker doses used in clinical practice are often substantially lower than those used in the randomized trials establishing their efficacy.

Objectives This study evaluated the association of beta-blocker dose with survival after acute MI, hypothesizing that higher dose beta-blocker therapy will be associated with increased survival.

Methods A multicenter registry enrolled 7,057 consecutive patients with acute MI. Discharge beta-blocker dose was indexed to the target beta-blocker doses used in randomized clinical trials, grouped as >0% to 12.5%, >12.5% to 25%, >25% to 50%, and >50% of target dose. Follow-up vital status was assessed, with the primary endpoint of time-to-death right-censored at 2 years. Multivariable and propensity score analyses were used to account for group differences.

Results Of 6,682 patients with follow-up (median 2.1 years), 91.5% were discharged on a beta-blocker (mean dose 38.1% of the target dose). Lower mortality was observed with all beta-blocker doses (p < 0.0002) versus no beta-blocker therapy. After multivariable adjustment, hazard ratios for 2-year mortality compared with the >50% dose were 0.862 (95% confidence interval [CI]: 0.677 to 1.098), 0.799 (95% CI: 0.635 to 1.005), and 0.963 (95% CI: 0.765 to 1.213) for the >0% to 12.5%, >12.5% to 25%, and >25% to 50% of target dose groups, respectively. Multivariable analysis with an extended set of covariates and propensity score analysis also demonstrated that higher doses were not associated with better outcome.

Conclusions These data do not demonstrate increased survival in patients treated with beta-blocker doses approximating those used in previous randomized clinical trials compared with lower doses. These findings provide the rationale to re-engage in research to establish appropriate beta-blocker dosing after MI to derive optimal benefit from this therapy. (The PACE-MI Registry Study—Outcomes of Beta-blocker Therapy After Myocardial Infarction [OBTAIN]: NCT00430612)

J Am Coll Cardiol. 2015;66(13):1431-1441. doi:10.1016/j.jacc.2015.07.047