A need for speed? Bypass time and outcomes after isolated aortic valve replacement surgery

OBJECTIVES: To determine in the modern era if cardiopulmonary bypass (CPB) time has a significant effect on postoperative morbidity, mortality and long-term survival in patients undergoing isolated aortic valve replacement (AVR) surgery. METHODS: Analysis of a prospectively collected cardiac surgery database was performed. Uni- and multivariate analysis on the need of resternotomy for bleeding, mediastinal blood loss, intensive care unit (ICU) length of stay, hospital length of stay, in-hospital mortality and long- term survival was performed. Only patients with a cross-clamp time <90 min were analysed to exclude technical issues confounding the results. RESULTS: A total of 1863 isolated first-time AVR procedures were analysed, with an in-hospital mortality rate of 2.4%. The rate of long-term follow-up achieved was 100%. Univariate analysis revealed that CPB time (minutes) had no significant effect on resternotomy (P = 0.5), creatinine kinase muscle-brain isoenzyme (CKMB) release (P = 0.8) and long-term survival (P = 0.06), but was significantly associated with mediastinal blood loss (P = 0.01), ICU length of stay (P = 0.02), hospital length of stay (P = 0.03) and in-hospital mortality (P < 0.001). Multivariate analysis identified that bypass time (min) was a significant factor associated with mediastinal blood loss (P < 0.001), ICU length of stay (P = 0.01), postoperative length of stay (P < 0.001) and in-hospital mortality (odds ratio [OR] 1.02, 95% CI 1.01-1.04, P = 0.01), but not long-term survival. Multivariate analysis identified that era of surgery had no significant effect on CKMB release (P = 0.2), mediastinal blood loss (P = 0.4) and in-hospital mortality (P = 0.9), but the latter era of this study was significantly associated with a reduced postoperative length of stay (P < 0.001), reduced ICU length of stay (P < 0.001), reduced need for resternotomy for bleeding (OR 0.62, 95% CI 0.41-0.94, P = 0.02) and improved long-term survival (hazard ratio 0.76, 95% CI 0.59-0.96, P = 0.02). Adjusting for era made no difference with respect to the above study findings. CONCLUSIONS: Despite improvements over time with regard to morbidity, mortality and long-term survival, CPB time remains a significant factor determining mediastinal blood loss, ICU and hospital length of stay, and in-hospital mortality.