Beta-blocker therapy in non-cardiac surgery

Learning from mistakes in clinical practice guidelines: the case of perioperative β-blockade

For more than two decades, the role of beta-blockers in preventing cardiac complications after major surgery has been the subject of contentious scientific and policy debate. Based on two small but highly publicized randomized trials published in 1996 and 1999, prominent U.S. organizations embraced preoperative beta-blocker initiation as a “best practice” and an opportunity for widespread safety improvement. Yet only a few years later, expert recommendations regarding preoperative beta-blockers were revised and downgraded when subsequent research failed confirm promising early findings and called attention to potential harms associated with beta-blocker overuse. In this paper, we trace the history of preoperative beta-blocker recommendations as a case study in lessons to be learned from reversals of guideline recommendations based initially on evidence drawn from randomized, controlled trials. Ultimately, we find that the policy significance that stakeholders ascribed to early beta-blocker studies combined with the prestige that experts assigned to the randomized controlled trial as a form of evidence to short-circuit discourse on the risks of preoperative beta-blocker initiation and led it to be elevated prematurely as a best practice. As such, the story of preoperative beta-blockers illustrates threats to objectivity in guidelines that can emerge from policy imperatives that lend primacy to the rapid translation of research into practice and from perspectives that unduly emphasize the strengths of randomized trials.

Beta-Blocker management in High-Risk Patients Presenting for Non-Cardiac Surgery: Before and after the POISE Trial

The POISE Trial was a randomised, placebo-controlled, double-blind study of the effectiveness of perioperative beta-blockade in preventing cardiac events including death in 8351 patients. Our hypothesis was that knowledge of the results of the POISE Trial would either increase or decrease the use of effective perioperative beta-blockade, depending on the result. Patients presenting for non-cardiac surgery and at risk of perioperative cardiac events were recruited in two cohorts before and after the release of the POISE Trial results. Effective perioperative beta-blockade was defined as heart rate <65 beats per minute for at least 80% of the perioperative period in patients prescribed beta-blockers. Effective perioperative beta-blockade was achieved in 22 (11.5%) of 191 patients prescribed perioperative beta-blockade in the first cohort (n=392) and seven (6%) of 118 patients in the second cohort (n=241) (P=0.10). Effective heart rate control was achieved in 29 (9%) patients prescribed perioperative beta-blockers compared with 10 (3%) patients not prescribed perioperative beta-blockers (P=0.001). The rate of implementation of effective beta-blockade was low before POISE and this did not change significantly after publication. Our finding does not provide reliable evidence of a change in practice as a result of the POISE Trial.