Heart rate control with beta blockers ‘impacts surgical outcomes’

21 October 2008

MedWire News: Perioperative beta-blockade (BB) is associated with higher rates of death and myocardial infarction (MI) at 30 days, a retrospective study of noncardiac patients has found.

Interestingly, BB-treated patients who died had higher preoperative heart rates than their surviving counterparts, a finding that highlights the importance of achieving adequate heart-rate control during noncardiac surgery.

The study, by Haytham Kaafarani (University of South Florida, Tampa, Florida, USA) and co-workers, investigated the relationship between BB use, heart rate control, and perioperative cardiovascular outcomes in patients undergoing various noncardiac surgical procedures.

The patients exhibited a broad spectrum of cardiac risk, Kaafarani et al remark. This is relevant as there is ongoing controversy about the optimal use of perioperative BBs in patients at various levels of cardiac risk.

In all, 238 patients taking BBs at the time of surgery were matched by age, gender, cardiac risk, procedure risk, smoking status, and renal function, with 408 patients not taking BBs.

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.

“The relationship between preoperative (rather than intraoperative or postoperative) heart rate and perioperative mortality stresses the importance of not only initiating but also titrating the effect of beta blockers to an acceptable target heart rate before surgery.”

In accompanying Invited Critique, Todd Rasmussen (Wilford Hall USAF Medical Center, San Antonio, Texas, USA) congratulates Kaafarani et al on their “insightful” study but suggests that residual confounding may have accounted for the difference in MI and survival rates between the groups.

“Without more detailed and uniform risk-stratification of patients in both groups, accounting for this bias is difficult, if not impossible,” he remarks. “I would encourage [the authors] to now turn their energy and expertise to a contemporary cohort using more powerful and complete methods.”

Arch Surg 2008; 143: 940–944