β-blockers did not decrease mortality in post-AMI patients without heart failure
β-Blockers and Mortality After Acute Myocardial Infarction in Patients Without Heart Failure or Ventricular DysfunctionDondo TB, Hall M, West RM, et al. - Journal of Am Coll Cardiol 2017; 69(22): 2710-20
Existing evidence supports the use of β-blockers in acute myocardial infarction (AMI) patients with heart failure (HF), as well as in hospitalized patients who are hemodynamically stable [1,2]. However, data regarding the impact of β-blockers on the mortality of AMI patients without HF or left ventricular systolic dysfunction (LVSD) are contradicting and medical guidelines include different recommendations for β-blockers after AMI [3-5].
In this analysis of the MINAP registry, the impact of β-blockers on all-cause mortality at 1 year was evaluated in 170,475 survivors of hospitalized AMI without HF or LVSD.
- Compared with those who did not receive β-blockers, patients who received β-blockers tended to be younger and male.
- Compared with patients who received β-blockers, those who did not, were more frequently comorbid and of higher ischemic risk, including diabetic mellitus (15.4% vs. 11.6%), chronic renal failure (3.2% vs. 1.6%), asthma or COPD (20.6% vs. 7.8%), cardiovascular disease (7.0% vs. 3.8%), and they had more frequently an intermediate or high Global Registry of Acute Coronary Events risk score (76.5% vs. 69.8%).
- The prescription of discharge medications, in-hospital procedures and enrolment into cardiac rehabilitation programmes was higher among those who received β-blockers.
- For the entire cohort with >163,772 person-years of observation (maximum 1-year follow-up), there were 9,373 deaths (5.2%).
- After propensity score matching, the unadjusted 1-year mortality was significantly lower for patients who received β-blockers compared with those who did not (4.9% vs. 11.2%, P<0.001).
- After weighting and adjustment, there was no significant difference in mortality when comparing patients with β-blockers compared with those who did not use β-blockers (average treatment effects coefficient at 1 month 0.47, 95% CI -2.99 to 3.94, P=0.785; at 6 months 0.06, 95% CI -0.35 to 0.46, P=0.768; at 1 year 0.07, 95% CI -0.60 to 0.75, P=0.827), neither for ST-segment elevation myocardial infarction (STEMI) nor for non-STEMI patients.
The use of β-blockers was not associated with lower all-cause mortality at any time point up to 1 year, in STEMI and non-STEMI patients without HF or LVSD, who survived hospitalization in the MINAP registry. These results add to the increasing body of evidence that routine prescription of β-blockers in AMI patients without HF or LVSD should be might not be indicated, but needs further investigation.
In their editorial article , Ibanez et al review briefly the history of β-blockers and note that opinions about their benefit in post-MI patients have changed dramatically, in the light of advances in the treatment of AMI patients. They recommend viewing the results of the study of Dondo et al with ‘’great caution’’ because of the following important limitations:
- the cut-off LVEF level used was 30%, although there is an established benefit from the use of β-blockers for LVEFs between 30% and 40%
- β-blockers were captured only at discharge and the treatment adherence during the follow-up year is unknown
- statistical consideration: it is not clear whether the estimated effect of propensity score-matched sample is representative of the entire cohort
The authors conclude: ‘’Thus, as the authors acknowledge, the present study should be viewed as hypothesis-generating and should not change clinical practice. However, this important report highlights the need to reboot the system: the role of β-blockers in post-MI patients without LVSD (LVEF >40%) needs to be evaluated from scratch.’’