Journal: Arch Surg 143(10):940-944, 2008. 14 References
Reprint: Dept of Surgery, Veterans Affairs Boston Healthcare System (112), 1400 VFW Pkwy, West Roxbury, MA 02132 (KMF Itani, MD)
Faculty Disclosure: Abstracted by L. Easley, who has nothing to disclose.
Patients with coronary artery disease or with risk factors for coronary artery disease who undergo noncardiac surgery are at significant risk for perioperative cardiac events such as death, stroke, and myocardial infarction (MI). Multiple mechanisms for postoperative MI have been suggested, many of which involve a hyperadrenergic state with sustained sinus tachycardia and increased myocardial oxygen demand. The present study was undertaken among patients at all levels of cardiac risk, and sought to determine the effect of β-blockers on perioperative heart rate (HR) and on perioperative cardiac morbidity and mortality in noncardiac surgery. Between January 1, 2000, and December 31, 2000, a total of 1238 patients undergoing general anesthesia for various noncardiac surgical procedures were screened and classified before surgery by the operating surgeon as high, intermediate, low, or negligible cardiac risk based on American College of Cardiology and American Heart Association (ACC/AHA) guidelines.
Patients included in the study underwent a noncardiac surgical procedure using general anesthesia within 6 months of the preoperative risk classification. Note was made of patients for whom β-blockers were started in the perioperative phase and of patients who were already receiving β-blockers before the operation for various reasons. For each patient, a preoperative HR (PreopHR) reading was documented before the induction of general anesthesia and the start of the operation. The β-blocker group was matched to a control group from the same patient population that did not receive β-blockers at the time of surgery. A total of 238 patients received β-blockers perioperatively. These patients constituted the β-blocker group and were matched to a control group of 408 patients who underwent noncardiac surgery at the same medical center during the same year but who did not receive perioperative β-blockade. The β-blocker group, having received perioperative β-blockers, had lower PreopHR, minimum HR and maximum HR. When outcomes in the 30-day postoperative period were evaluated and compared, patients in the β-blocker group had significantly higher incidences of nonfatal MI, total cardiovascular morbidity, and all-cause mortality. In the β-blocker group only, the mean PreopHR of the patients who died within 30 days of their surgery was significantly higher than that of the patients who survived.
Despite many studies in the past three decades, controversy continues regarding the indications and proper use of β-blockers in noncardiac surgery. Most studies have not evaluated the effect of β-blockers in patients at intermediate or low cardiac risk. In this study of patients at all levels of cardiac risk, including higher proportions of low-risk and intermediate-risk patients, β-blockers failed to provide perioperative cardioprotection. Unexpectedly, patients receiving β-blockers were at higher risk of 30-day cardiovascular events and overall mortality. The study analysis demonstrates that the patients who died within 30 days of their operation were not classified as high-risk patients and this raises questions about the safety of β-blockers in low-risk or intermediate-risk patients.
This study adds to the controversy regarding the optimal use of perioperative β-blockers in patient populations at various levels of cardiac risk. Overall, the study data found worse perioperative cardiovascular outcome and worse overall mortality associated with the use of β-blockers. Patients who died were at less than high cardiac risk and had worse PreopHR control. |
