Minimally Invasive Approach for Mitral Valve Surgery Is Associated With Increased Risk of Postoperative Diaphragm Dysfunction

Objective: Minimally invasive mitral valve (MIMV) surgery has increased in prevalence due to reduced postoperative pain, length of stay, and improved cosmesis. However, there is a lack of data describing the risk and impact of postoperative diaphragm dysfunction (DD) after MIMV. Methods: Consecutive patients at a single institution undergoing isolated mitral valve surgery either via full sternotomy (FS) or MIMV (right thoracotomy) between 2015 and 2024 were included. The diagnosis of DD was based on postoperative diaphragm elevation on chest X-ray and confirmation via ultrasound Sniff test. Factors associated with postoperative DD were identified, and postoperative outcomes were compared between groups. Results: The incidence of postoperative DD was 3.0% ( n = 35) among the 1,155 patients undergoing MV surgery. The incidence of DD was 1.8% after FS and 9.3% after MIMV ( P < 0.001). Among MIMV patients, all suffered from right DD. After controlling for age, body mass index, and pulmonary comorbidities, MIMV was independently associated with postoperative DD compared with FS (odds ratio = 5.1, 95% CI: 2.4 to 11.0, P < 0.001). Although patients with and without DD had similar postoperative outcomes, those patients older than 70 years with DD had longer postoperative ventilation times ( P = 0.03) and hospital length of stay ( P = 0.02). Conclusions: MIMV via right thoracotomy is associated with increased risk of postoperative DD and increased ventilation times and hospital length of stay for elderly patients. Further studies are needed to elucidate the causes for diaphragm injury to minimize this complication.