Risk Factors for Higher Postoperative Myocardial Injury in Minimally Invasive Mitral Valve Surgery Patients: A Cohort Study

Background: Postoperative myocardial injury, as detected by an elevated concentration of high-sensitivity cardiac troponin I (hs-cTnI), is a common complication in cardiac surgery that may be linked to mortality. The primary aim of this study was to assess the risk factors associated with increased myocardial injury in patients undergoing minimally invasive mitral valve surgery. Methods: In this retrospective monocentric cohort study, we analyzed all patients who underwent elective minimally invasive mitral valve surgery between January 2019 and December 2022 and were subsequently admitted to our intensive care unit. The study population was divided into two groups based on the peak hs-cTnI level: the "lower myocardial injury" group comprised patients whose peak serum hs-cTnI level was less than 499 times the 99th percentile, while the "higher myocardial injury" group included those patients who exhibited hs-cTnI levels equal to or greater than 500 times the 99th percentile. A multivariable logistic regression analysis was performed to identify independent risk factors associated with higher myocardial injury. Results: In our final analysis, we enrolled 316 patients. Patients with higher myocardial injury (48; 15%) more frequently had a preoperative New York Heart Association (NYHA) class >= 3 compared to those with lower myocardial injury [33 (69%) vs. 128 (48%); p < 0.01-OR 2.41 (95% CI 1.24-4.64); p < 0.01]. Furthermore, cardiopulmonary bypass and aortic cross-clamp time were significantly longer in the higher myocardial injury group compared to the lower myocardial injury group [117 (91-145) vs. 86 (74-100) min; p < 0.01-OR 1.05 (95% CI 1.03-1.06); p < 0.01]. Moreover, patients who underwent robotic-assisted mitral valve surgery experienced lower myocardial injury rates [9 (19%) vs. 102 (38%); p = 0.01-OR 0.38 (95% CI 0.18-0.81); p = 0.01] than others. These findings remained consistent after adjustment in multivariate logistic regression. In terms of postoperative outcomes, patients with higher myocardial injury exhibited the highest lactate peak in the first 24 h, a higher incidence of postoperative acute kidney injury and a longer duration of mechanical ventilation. Although no patients died in either group, those with higher myocardial injury experienced a longer hospital length of stay. Conclusions: Higher myocardial injury is relatively common after minimally invasive mitral valve surgery. Prolonged aortic cross-clamp duration and higher NYHA class were independently associated with myocardial injury, while robotic-assisted mitral valve surgery was independently associated with lower postoperative myocardial injury.