Treatment of Pre-Induction Tachycardia with beta-Adrenergic Blockade Reduces Mortality after CABG

Fillinger, M. P.; Surgenor, S. D.; Dodds, T. M.; Clark, C.; Johnson, D.

Introduction: Previously we reported that pre-induction tachycardia was associated with increased mortality after coronary artery bypass graft surgery (CABG). beta-adrenergic blocker therapy for ischemic heart disease has been associated with improved survival after CABG surgery. The purpose of this study was to observe the impact of beta-adrenergic blockade given in the Operating Room before initiation of cardiopulmonary bypass (CPB). Methods: Data were prospectively collected at 6 medical centers in Northern New England on 5,934 patients undergoing isolated CABG surgery between March, 1995 and June, 2000. Patients who had isolated valve or combined/valve CABG surgery were excluded from this study. Pre-induction heart rate was defined as heart rate upon arrival to the Operating Room and was collected by the anesthesiologist. Patients were divided into two groups as defined by the presence or absence of pre-induction tachycardia. Tachycardia was defined as 80 beats per minute (bpm) or greater. The use of beta-adrenergic blockade during the pre-CPB period was also collected. The pre-CPB period was defined as the time period between arrival in the Operating Room and the onset of CPB. Logistic regression analysis was used to calculate adjusted mortality rates. Results: Fifteen percent of this population (n=880) had tachycardia upon arrival to the Operating Room. The use of beta-blockers was 11.6% in patients with heart rate <80 bpm and 25.5% in patients with heart rate gtoreq 80 bpm. Tachycardic patients receiving beta-blockers were less likely to have a preop EF<40% compared with those not receiving beta-blockers (15.7% vs. 22.3%). The groups were not significantly different in age, percent female, incidence of major comorbid conditions, prior CABG, or priority at surgery. Crude mortality rates among tachycardic patients were 1.3% for those receiving beta-blockade vs. 5.5% among those who did not. After adjustment for patient and disease risk factors, mortality for the tachycardic beta-blocker group was still significantly lower (1.3% with beta-blockers vs. 4.2%, without). No association between mortality and beta-blocker use was seen in patients whose pre-induction heart rate was <80 bpm (mortality rate of 1.6% in patients who received a beta-blocker compared to a mortality rate of 1.8% in patients who did not receive a beta-blocker.) Conclusion: Use of beta-adrenergic blocker therapy prior to CABG surgery is associated with improved in-hospital survival. A similar association was seen in this multicenter prospective study. We observed that tachycardic patients who received beta-blockers in the pre-CPB period had a lower in-hospital mortality rate after CABG than those who did not receive beta-blockers.