ObjectiveTo monitor surgical quality and analyze learning curve of minimally invasive mitral valve replacement (MVR)through right minithoracotomy with cumulative sum analysis (CUSUM analysis). MethodsClinical data of 60 consecutive patients who underwent minimally invasive MVR through right minithoracotomy in the Fourth Affiliated Hospital of Guangxi Medical University from June 2011 to April 2013 were retrospectively analyzed. There were 32 male and 28 female patients with their age of 28-53 (34.67±7.11)years and their heart function ranging from NYHA class Ⅱ to Ⅳ. There were 31 patients with mitral stenosis (MS), 19 patients with mitral regurgitation (MR), and 10 patients with MS and MR. According to the surgical sequence, all the patients were divided into 3 groups (group A, B and C)with 20 patients in each group. Surgical outcomes were compared among the 3 groups, and surgical quality was analyzed with descriptive statistics and CUSUM curves. ResultsAortic cross-clamp time, cardiopulmonary bypass time and operation time of group C were significantly shorter than those of group A and group B (aortic cross-clamp time of group C vs. group A:50.35±2.30 minutes vs. 66.15±8.38 minutes; operation time of group C vs. group B:167.50±4.63 minutes vs. 178.60±4.49 minutes, P < 0.05). In-hospital mortality was 3.3% (2/60). CUSUM analysis showed a significant learning curve effect, although surgical quality remained in control during the study period. Surgical failure rate was lower than 80% after about 45 operations, indicating that failure rate was 10% lower than expectation. ConclusionMinimally invasive MVR is safe and reliable, and CUSUM analysis is a simple statistical method to monitor surgical quality.