Introduction

For more than two decades, the role of β-blockers in preventing cardiac complications after surgery has been among the most hotly contested and controversial topics in medical practice. Based on two small randomised trials published in the late 1990s,1 ,2 leading physicians and experts in patient safety embraced preoperative β-blocker initiation as a therapeutic victory for high-risk surgical patients: an apparently simple and effective treatment that promised, for the first time, to prevent life-threatening postoperative cardiac events.

Yet nearly as soon as preoperative β-blocker initiation had come to be seen as a ‘best practice’, its status was cast into doubt. New randomised trials published between 2005 and 2008 failed to confirm promising early findings and highlighted the potential for harm with β-blocker overuse.3–6 Recommendations that had previously urged widespread preoperative β-blocker initiation among high-risk patients7 ,8 were softened or reversed.9 ,10 Debates over whether or not β-blockers were safe for surgical patients displaced discussions on how to promote their use on a large scale.

On one level, what may be most remarkable about the rise and fall of preoperative β-blocker guidelines is how unremarkable it seems. Preoperative β-blockade is only one of several recent examples in which expert endorsements of promising therapies changed markedly when new evidence highlighted potential harms that had been overlooked by these endorsements. Yet the β-blocker story differs in important ways from canonical examples of reversals in recommendations for medical practice. Prominent retellings of how expert recommendations changed regarding hormone replacement therapy (HRT) for women after menopause, for example, have emphasised the pitfalls of relying on non-randomised studies rather than randomised controlled trials in defining benefits and harms of therapies.11 ,12 In contrast, preoperative β-blocker initiation was elevated rapidly to the status of a best practice specifically …