Mechanism and Clinical Significance of Mitral Regurgitation in Cardiac Sarcoidosis

Backgrounds: Mitral regurgitation (MR) is sometimes observed in cardiac sarcoidosis (CS), and might be related to worsening heart failure. However, mechanism and clinical significance of MR associated with CS remains unknown. Methods and Results: To clarify this issue, we retrospectively analyzed consecutive 41 CS patients, and identified 14 patients with moderate to severe MR. We compared clinical findings, treatment and outcome between patients with and without MR. Mechanism of MR consists of prolapse in 5, and tethering in 9 including 6 symmetric and 3 asymmetric leaflet tethering. Incidence of complete AV block was significantly greater in patients with tethering MR (P < .05), whereas the incidence of thinning in the basal septum was similar. Significantly reduced left ventricular (LV) ejection fraction (P < .01) and increased LV end-diastolic volume index (P < .01) were observed in patients with tethering MR. Cardiac resynchronization therapy in 4 and mitral valve replacement in 2 of the 14 with MR were received before or after corticosteroid therapy. A cardiac event including cardiac death and arrhythmias or heart failure requiring hospitalization occurred 9 patients during the mean follow-up of 79 months. Cardiac-event free survival was significantly worse in patients with MR due to tethering (P < .001) Conclusions: MR associated with CS has variety of mechanism. Existence of tethering MR is strongly related to worsening heart failure and poor outcome in CS.