b-blockers in COPD patients post-MI

There have been several articles over the past 1-2 decades suggesting that the vast majority of patients denied b-blockers post-MI (most of whom had COPD) clinically should have been prescribed b-blockers, albeit carefully. a recent analysis in BMJ retrospectively accessed a large UK electronic database from 2003-8, assessing whether COPD patients with an MI were prescribed b-blockers, and what their clinical outcome were (see cad bblockers postMI in COPD bmj2013 or doi: 10.1136/bmj.f6650).  results:

--there were 1063 patients with COPD who were hospitalized with an MI in the cohort. not surprisingly, some differences between those prescribed b-blockers and those not (those put on b-blockers were younger and less likely to have history of hypertension, PAD, heart failure, dyslipidemia, angina prior to MI). GOLD staging was similar between the groups. only 40% of patients with MI and COPD were prescribed b-blocker while in the hospital

--med adherence was 80% at one year, decreasing to 60% at 2 years (suggesting those prescribed b-blockers tolerated them pretty well)

--those started on b-blockers during the admission for MI had significantly increased survival (adjusted hazard ratio of 0.50), with median followup of 2.9 years. one-year survival in those prescribed a b-blocker during the hosp admission for MI also had adjusted hazard ratio of 0.48.

--those already on b-blockers when admitted to hospital with their MI had survival benefit at well (hazard ratio of 0.59)

--cause of death evenly divided between cardiac and non-cardiac causes, and both were decreased by about 50% in patients put on b-blockers (a bit surprising, but they cite a paper -- doi.org/10.1136/bmj.d2549 , or BMJ 2011;342:d2549 -- finding that b-blockers were associated with decreased COPD mortality as well as cardiovasc, in line with their findings)

so, one issue here is that patients with COPD are at higher risk for cardiovasc dz (common risk factor/smoking, perhaps inflammation). recent studies have challenged the "prevailing wisdom" that b-blockers are dangerous to use in patients with COPD by increasing bronchospasm (that being said, it makes sense to start low, titrate up more slowly, and preferentially use cardioselective b-blockers -- eg atenolol, metoprolol, though in this UK group bisolprolol was most commonly prescribed). based on a few studies done in the US showing tolerability of b-blockers and suggestive evidence that survival is improved post-MI, the use of b-blockers post-MI has increased into the 90+% range in patients with COPD. the patients in this study put on b-blockers were younger and healthier. they tried to mathematically control for these disparities, but this observational study might well have had unmeasured confounding biases.

bottom line: this is an observational study and may well be flawed. but the convergence of evidence suggests strongly that COPD patients, who are at high risk for CAD, should be given a trial of b-blockers post-MI, although probably beginning at low dose and titrated up as tolerated, and preferentially using a cardioselective one. (i think the same argument holds for patients with heart failure and significantly reduced ejection fraction).  i would, however, be especially careful in those patients with asthma or those with COPD but a strong reversible component.