Surgical factors and complications affecting hospital outcome in redo mitral surgery: insights from a multicentre experience

OBJECTIVES: Several single-centre experiences have reported significant operative mortality and morbidity after mitral valve surgery in redo scenarios (ReMVS). Several preoperative risk factors outlining `high-risk' categories have been reported, but scanty data on the impact of different operative techniques for these major challenging procedures have been analysed to date. The aim of the study is to investigate those intraoperative factors and postoperative events affecting early survival after redo mitral procedures. METHODS: Operative mortality and major morbidity events from a large multicentre registry enrolling 832 consecutive redo mitral procedures were analysed. Intraoperative technical issues and postoperative complications impacting operative mortality were identified. RESULTS: ReMVS was associated with significant operative mortality (12.5%), acute myocardial infarction (AMI; 5.9%), stroke (4.9%), acute respiratory insufficiency (14.8%), pneumonia (7.0%), acute renal insufficiency (16.1%) and failure (12.6%), reintervention for bleeding (7.6%), massive transfusion (28.0%), need for permanent pacemaker (10.1%). Injury of a previous patent left internal mammary artery (LIMA) graft [odds ratio (OR) 4.2, 95% confidence interval (CI): 1.6-11.5; P = 0.005], major cardiovascular iatrogenic lesions at re-entry (OR 19.2, 95% CI: 9.2-39.9; P < 0.001), extracellular crystalloid cardioplegia (OR 7.3, 95% CI: 1.4-37.8; P = 0.018), and incremental cardiopulmonary bypass time (OR 1.1, 95% CI: 1.0-1.2; P = 0.001) independently predicted operative mortality, whereas combined antegrade + retrograde cardioplegia (OR 0.2, 95% CI: 0.09-0.4; P = 0.001) was the only protective factor against mortality. Among complications, AMI (OR 4.1, 95% CI: 1.8-9.6; P = 0.001), need for intra-aortic balloon pumping (IABP; OR 3.1, 95% CI: 1.5-6.1; P = 0.001), prolonged intubation >48 h (OR 5.3, 95% CI: 2.9-9.4; P = 0.001) and massive (>6 units) transfusions (OR 4.4, 95% CI: 2.4-8.0; P = 0.001) also predicted operative mortality. CONCLUSIONS: ReMVS still carries the risk of significant early mortality and major morbidity. Major lesion to cardiovascular structures is the most dreadful iatrogenic complication, and injury of a previous LIMA graft identifies patients at higher risk of operative mortality. Prolonged cross-clamp times, extracellular crystalloid cardioplegia and massive transfusions have profound impact on early outcome, as well as the development of perioperative AMI, eventually requiring IABP and prolonged intubation. The combination of antegrade and retrograde cardioplegia seems to offer a better myocardial protection in these high-risk patients.