Commentary: Preoperative β-blockers—One size does not fit all when considering management

Abstract

The use of perioperative b-blocker therapy as a strategy to prevent cardiac related complications has been highly controversial. [1][2][3] In the study in this issue of the Journal by Shubert and colleagues 4 of patients undergoing isolated aortic valve surgery, a remarkable 53% of patients were receiving preoperative b-blocker therapy. The major question raised by Shubert and colleagues 4 was whether this had a negative effect on the outcomes. They have previously raised the issue of whether the policy of requiring b-blocker use as a quality metric for coronary bypass grafting should be considered valid, even though it has been advocated by our major organizations. 5 It is true that there is evidence to support the use of b-blockers for preoperative medical treatment in patients with severe aortic stenosis, 6 and this may explain why such a high percentage of their patients were receiving preoperative b-blockers.For accurate assessment of the consequences of the perioperative use of b-blocker, a study must include more than whether the patient was receiving the drug before the operative procedure. Shubert and colleagues 4 point this out clearly in their list of limitations, which includes ''which b-blockers and dosages were used, timing and duration of b-blocker therapy, heart rate and blood pressure variation, technical intraoperative details, or postoperative vasopressor requirements.'' They also have not specified what proportion of patients actually had b-blockers continued postoperatively and whether corrective interventions such as overdrive atrial pacing to optimize heart rates were used. There is also evidence that the type of b-blocker can have a significant effect on outcomes, 7 and the types used were not specified.It is also noted that in both groups of Shubert and colleagues, 4 approximately 27% had moderate to severe aortic insufficiency. Although consideration of the pathophysiology of aortic insufficiency and the dependence on an adequate heart rate to optimize hemodynamics and prevent diastolic distention would suggest that b-blocker therapy would be detrimental, there is 1 study 8 that showed that it had a benefit as long as the heart rate was 70 beats/min or faster. That study, however, did not permit heart rate to be less than 70 in these patients. 8 Because more than onequarter of their study group had significant aortic insufficiency, Shubert and colleagues 4 should have verified that the preoperative heart rates were adequate to prevent these patients from entering the operation with compromised ventricles.Although Shubert and colleagues 4 clearly established 2 carefully matched groups to assess the effect of preoperative b-blockers versus no preoperative b-blockers, it remains unclear whether the b-blocker group may have had other risk factors, such as preoperative remote episodes of atrial fibrillation, to raise their risk or whether this same group had their b-blockers stopped early after operation, thus increasing their risk of atrial fibrillation from b-blocker withdrawal.What this st...

Reply from the authors: Big data and beta blockers: The best of times, the worst of times

“…As all commentators and our limitations section note, the beta-blocker type, dose, and duration were not avilable. [2][3][4][5][6][7] As Mazzeffi and colleagues 4 correctly point out, there is large variability in beta selectivity among the different agents. We can only make assumptions, and a reasonable one would be that prescribing practices mirror the general population, for whom the majority receive nonselective agents.…”

“…The next concern is whether the beta-blocker cohort is simply a sicker group of patients with expected greater rates of complications. 2,3,6,7 The propensity matching was able to define a remarkably homogenous and similar group of patients. The STS-predicted risk of mortality was exactly 2.1% in both matched groups.…”