Are lipophilic beta-blockers preferable for peri-operative cardioprotection?

Abstract

Atenolol has been proposed as a peri-operative cardioprotective agent in patients with coronary disease. However, recent reports have cast doubt over the cardioprotective efficacy of atenolol in patients with hypertension and coronary artery disease. There is therefore doubt whether atenolol is the correct cardioprotective drug in the surgical setting. It is possible that some of the physiochemical properties of atenolol (hydrophilic and cardioselective) may decrease it's efficacy in comparison to its more lipophilic congeners (such as propranolol, metoprolol, bisoprolol and carvedilol). The issue of prevention of perioperative cardiac events is complicated by many confounders. As a result, the role of the physicochemical properties of beta-blockers can only be determined in the simpler setting of myocardial infarction. Therefore, we conducted a restricted systematic review to evaluate the effect of initiating atenolol and metoprolol on the prevention of ventricular fibrillation following acute myocardial infarction. Neither atenolol nor metoprolol significantly decreased the incidence of in-hospital ventricular fibrillation following acute myocardial infarction. The number-needed-to-treat to prevent in-hospital ventricular fibrillation equals or exceeds 200 with metoprolol and atenolol respectively. Based on the findings of this systematic review and the recently published Clopidogrel and Metoprolol in Myocardial Infarction Trial (COMMIT), it can be concluded that the prevention of peri-operative myocardial ischaemia with a betablocker is clinically more important to peri-operative cardioprotection than whether the beta-blocker is lipo- or hydrophilic.

Keywords: atenolol, metoprolol, myocardial infarction, ventricular fibrillation

Southern African Journal of Anaesthesia and Analgesia Vol. 12(4) 2006: 141-146