This study tested whether atenolol (a long acting beta-blocker) and metoprolol (a short acting beta-blocker) are associated with equivalent reductions in risk for elderly patients undergoing elective surgery.

The study group included patients older than 65 year of age who were admitted to acute care hospitals in Ontario, Canada over one decade for elective surgery, without symptomatic coronary disease. The main outcome measure was death or myocardial infarction.

A total of 37,151 patients were receiving atenolol or metoprolol before surgery, of which the most common operations were orthopaedic or abdominal procedures.  As expected, the two groups were similar in demographic characteristics, medical therapy, and type of surgery.  A total of 1,038 patients experienced a myocardial infarction or died, a rate that was significantly lower for patients receiving atenolol than for those receiving metoprolol (2.5% vs. 3.2%, P < 0.001).  The decreased risk with atenolol persisted after adjustment for measured demographic, medical, and surgical factors; extended to comparisons of other long acting and short acting beta-blockers; was accentuated in analyses that focused on patients with the clearest evidence of beta-blocker treatment; and reflected the immediate postoperative interval.

Patients receiving metoprolol do not have as low a perioperative cardiac risk as patients receiving atenolol, in accord with possible acute withdrawal after missed doses.