Congenital Mitral Rings: Insights From a Single-Institution Study and Review of Current Literature

BackgroundCongenital mitral rings represent a rare subset of congenital mitral stenosis often associated with complex cardiac anomalies. Comprehensive literature on congenital mitral rings, particularly from large single-institution experiences, remains sparse. Methods: This retrospective study, conducted at All India Institute of Medical Sciences, New Delhi, analyzed data from 52 patients who underwent surgical correction for congenital mitral rings between 2014 and 2024. Data on demographics, clinical presentation, preoperative echocardiographic and cardiac catheterization parameters, associated cardiac anomalies, intraoperative findings, and postoperative outcomes were collected. Patients had a mean follow-up of 72 months.ResultsThe cohort had a mean age of 6 years. An isolated vestibular mitral ring was noted in only 1 patient, with 51 cases showing associated cardiac anomalies. The mean preoperative diastolic gradient was 13 mm Hg, significantly reduced to 2.69 mm Hg in the immediate postoperative period and 3.35 mm Hg at follow-up. Two distinct morphological types were identified: "distinct vestibular supramitral ring" (43 patients) and "adherent intramitral ring" (9 patients), with the latter demonstrating a higher association with subvalvular apparatus abnormalities. Preoperative transesophageal echocardiography proved crucial in detecting these rings in 4 cases where the diagnosis was doubtful on transthoracic echocardiography. Surgical outcomes were favorable, with 1 early postoperative mortality and 3 late mortalities. Four patients required reinterventions for residual lesions, achieving successful resolution.ConclusionThis large single institution series provides valuable insights into associated anomalies, morphological variants, and long-term surgical outcomes of congenital mitral rings. Accurate diagnosis and timely surgical intervention led to favorable outcomes, reinforcing the need for thorough preoperative evaluation.