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Perioperative consultation for "surgical clear-ance" is a common activity for many internists and family physicians. Contemporary strategies for risk stratification of patients for potential surgical-associated cardiac events began 20 years ago with the Goldman classification.1 About 10% of patients undergoing non-cardiac surgery have or are at risk for coronary artery disease. Recent studies have shown that the risk of serious cardiovascular outcomes extends beyond the immediate surgical window up to two years after surgery. Based on preliminary studies and the observation that postoperative ischemic events appear to be related to an exaggerated increase in heart rate, the investigators performed a double-blind, placebo-controlled, randomized controlled trial of perioperative atenolol (a beta-blocker) compared to placebo. The actively treated group received treatment before the induction of anesthesia, immediately after surgery, and daily up to seven days later. A specific algorithm for drug dosing based on heart rate and blood pressure were used. Two hundred patients with either known coronary artery disease (39%) or risks factors were randomized.
The investigators found no difference in the in-hospital mortality rate between groups. However at six, 12, and 24 months after discharge, the atenolol-treated group had a persistent benefit. For example, at six months after discharge, no additional atenolol-treated patients died vs. 8% of placebo. At 24 months, the combined cardiovascular outcomes were event-free survival of 83% in the atenolol group vs. 68% in the placebo. The number needed to treat (NNT) ratio to avoid one event was seven.
Given the simplicity of the intervention, the minimal additional monitoring, low costs, and large effect, the use of peri-operative atenolol should, based on this study, become a standard of care for all patients with cardiac risk factors.
1. N Engl J Med 1995;333:1750.