Give beta-blockers pre-op. Wait... don't. Well, maybe. / by Methods Man

Nancy_Wilson_and_Roger_Fisher_-_Heart_-_1978.jpg

For the video version of this post, click here. When I was training as a medical resident, we used to do all these consults for perioperative clearance, or, more politically, perioperative risk-stratification.  The idea is that, before elective surgery, we’d go in and take a detailed history and decide if the patient needed any additional workup before they went under the knife.  Not infrequently, we’d suggest perioperative beta-blockade.  The idea was that the stress of surgery put a strain on the heart, and the beta-blockers would prevent post-op cardiac complications.

The rationale for this behavior was bolstered by something called the DECREASE IV trial, which randomized pre-operative patients to get a beta-blocker or placebo, and showed that those who got the beta-blocker were significantly less likely to experience a cardiac event. But a subsequent trial, called POISE, found that those who got beta-blockers had an increased risk of all-cause mortality.  It also emerged that the DECREASE trial had serious ethical flaws, and that some of the data may have been fabricated.  

Still, the biologic rationale is there, so what do we do?  Well, a paper appearing in JAMA-internal medicine attempts to answer this question, albeit in a very roundabout way.  Let’s see if we can get there.

Danish researchers used that country’s impressive electronic health record database to identify 55,320 individuals who underwent non-cardiac surgery between 2005 and 2011. This number excluded anyone with any sort of heart disease, though all of the patients had hypertension.  In fact, they were all taking at least two anti-hypertensives, which makes this a rather unique cohort to begin with. It turned out that the 30-day mortality risk was 1.93% in those taking beta-blockers compared to 1.32% in those taking other anti-hypertensives. This relationship persisted even after adjustment for things like age, sex, surgical risk, and comorbidities. So… case-closed? We shouldn’t give people beta-blockers pre-operatively?

Well, not so fast. This study only looked at those who were already taking beta-blockers - it doesn’t really tell us anything about what happens if you start a beta-blocker pre-op. Moreover, people get beta-blockers for a reason. That reason often involves some practitioner deciding the patient is at risk of some type of cardiac event, meaning the deck might have been stacked against beta-blockade from the beginning.  Also, restricting the cohort to those on two anti-hypertensives really limits what we can apply to most patients.

The American College of Cardiology currently recommends keeping patients on beta-blockers perioperatively if they were already on beta-blockers. I’d be very surprised if this study leads to any sort of change of heart.