Mitral annular disjunction was detected not only in patients with a myxomatous mitral valve but also in normal cases. The number of MVPs was significantly larger in patients with mitral annular disjunction than patients without mitral annular disjunction. Further investigation is needed to clarify the clinical significance of the mitral annular disjunction detected by routine echocardiography.

Background Mitral annular disjunction is a structural abnormality of the mitral annulus fibrosus which is often associated with mitral leaflet prolapse. However, few reports have described mitral annular disjunction in mitral valve prolapse (MVP). This study aimed to investigate the characteristics of mitral annular disjunction in patients with severe mitral regurgitation (MR) caused by MVP. Methods We reviewed 185 consecutive patients with severe MR caused by fibroelastic deficiency (FED) and Barlow's syndrome from March 2009 to December 2010. The upper limit of the disjunction was defined at the level of the posterior scallop's insertion into the left atrial wall, whereas the lower limit was defined at the level of the left atrium's connection to the ventricular myocardium. The distance between the two levels was called mitral annular disjunction. Prolapse sites in FED patients were categorized into anterior leaflet, posterior leaflet, and commissure groups. Patients with a disjunction distance of ≥2 mm were diagnosed with mitral annular disjunction. Results Annular disjunction was found in 45 patients (24%). Among them, the most common site of prolapse was the posterior leaflet (n = 35, 77.8%). During a median follow‐up of 20.3 years, arrhythmic events and sudden death occurred in seven patients (3.8%). Conclusions Mitral annular disjunction was detected in 24% of patients with severe MR and in 90% of the patients with Barlow's syndrome. There were significant differences at its sites of prolapse in FED patients. The presence and site of prolapse with mitral annular disjunction should be actively determined in FED patients.

Isolated papillary muscle hypertrophy can cause ECG abnormalities such as LV high voltage and LV strain pattern. Particular attention must be paid to the papillary muscle during echocardiographic examinations.