ß-blockade increases risk of MI, death, after non cardiac surgery

Patients who receive ß-blockers before undergoing non-cardiac surgery have higher rates of MI and death with 30 days of their surgery, a study has found. Interestingly, the researchers found that ß-blocker (BB) treated patients who died had higher preoperative heart rates than their surviving counterparts, a finding that they say highlights the importance of not only initiating but also titrating the effect of beta blockers to an acceptable target heart rate before surgery. The study matched 238 patients taking BBs at the time of surgery by age, gender, cardiac risk, procedure risk, smoking status, and renal function, with 408 patients not taking BBs. Patients were classified into high, intermediate, low, or negligible cardiac risk categories based on the ACC/AHA classification. At 30 days post-surgery, the BB group had significantly higher rates of MI (2.94% vs 0.74%, p=0.03) and death (2.52% vs 0.25%, p=0.007) compared with controls. None of the deaths occurred among patients classified as high cardiac risk. The BB group had lower preoperative and intraoperative heart rates at all levels of cardiac risk; within the BB group, patients who died had significantly higher preoperative heart rates (86 vs 70 beats per minute, p=0.03) compared with survivors. “As subtle as it may be, this finding suggests that a low target preoperative rather than intraoperative heart rate is essential for the protective effect of beta blockers,” the authors write. An accompanying Invited Critique said it was likely that patients in the ß-blocker group were at higher risk, having been identified as candidates for ß-blocker therapy. “Without more detailed and uniform risk-stratification of patients in both groups, accounting for this bias is difficult, if not impossible,” it remarked. “I would encourage [the authors] to now turn their energy and expertise to a contemporary cohort using more powerful and complete methods,” it said....