Operative mortality in adult cardiac surgery: is the currently utilized definition justified?

Background: This study evaluated operative mortalities following adult cardiac surgical operations to determine if this metric remains appropriate for the modern era. Methods: This was a retrospective review of Society of Thoracic Surgeons (STS) indexed adult cardiac operations that included coronary artery bypass grafting (CABG), aortic valve replacement (AVR), CABG + AVR, mitral valve repair (MVr), CABG + MVr, mitral valve replacement (MVR) and CABG + MVR, performed at a single institution between 2011 and 2017. The primary outcome was the timing and relatedness of operation mortality, as defined by the STS as mortality within 30-day or during the index hospitalization, compared to the index operation. The secondary outcomes evaluated cause of death and the rates of postoperative complications. Results: A total of 11,190 index cardiac operations were performed during the study period and operative mortality occurred in 246 (2.2%) of patients. The distribution of operative mortalities included 83.7% (n=206) who expired within 30-day while an inpatient, 6.9% (n=17) died within 30-day as an outpatient, 11.2% (n=23) expired after 30-day. The most common causes of operative mortality were cardiac (38.7%, n=92), renal failure (15.6%, n=37), and strokes (13.9%, n=33). Furthermore, 98.4% (n=242) of deaths were attributable to the index operation. Postoperative complications occurred frequently in those with operative mortality, with blood transfusions (80.1%), reoperations (65.0%) and prolonged ventilation (62.2%) being most common. Conclusions: Most of the operative mortalities seemed to be attributable to the index cardiac operation. We believe that the current definition of mortality remains appropriate in the modern era.