Aortic cross-clamp time correlates with mortality in the mini-mitral international registry

OBJECTIVES: Minimally invasive access has become the preferred choice in mitral and/or tricuspid valve surgery. Reported outcomes are at least similar to classic sternotomy although aortic cross-clamp times are usually longer. METHODS: We analysed the largest registry of mitral and/or tricuspid valve surgery patients (mini-mitral international registry (MMIR)) for the relationship between aortic cross-clamp times, mortality and other outcomes. From 2015 to 2021, 7513 consecutive patients underwent mini-mitral and/or tricuspid valve surgery in 17 international Heart-Valve-Centres. Data were collected according to Mitral Valve Academic Research Consortium (MVARC) definitions and 6878 patients with 1 cross-clamp period were analysed. Uni- and multivariable regression analyses were used to assess outcomes in relation to aortic cross-clamp times. RESULTS: Median age was 65 years (57% male). Median EuroSCORE II was 1.3% (Inpatient Quality Reporting (IQR): 0.80-2.63). Minimally invasive access was either by direct vision (28%), video-assisted (41%) or totally endoscopic/robotic (31%). Femoral cannulation was used in 93%. Three quarters were repairs with 17% additional tricuspid valve surgery and 19% Atrial Fibrillation (AF)-ablation. Cardiopulmonary bypass and cross-clamp times were 135 min (IQR: 107-173) and 85 min (IQR: 64-111), respectively. Postoperative events were death (1.6%), stroke (1.2%), bleeding requiring revision (6%), low cardiac output syndrome (3.5%) and acute kidney injury (6.2%, mainly stage I). Statistical analyses identified significant associations between cross-clamp time and mortality, low cardiac output syndrome and acute kidney injury (all P < 0.001). Age, low ejection fraction and emergent surgery were risk factors, but variables of `increased complexity' (redo, endocarditis, concomitant procedures) were not. CONCLUSIONS: Aortic cross-clamp time is associated with mortality as well as postoperatively impaired cardiac and renal function. Thus, implementing measures to reduce cross-clamp time may improve outcomes.