Caseous calcification of the mitral annulus associated with a complete atrioventricular block: a case report.

Background: Caseous calcification of the mitral annulus (CCMA), a subtype of mitral annulus calcification, is rarely encountered. Although most cases of CCMA are asymptomatic and have a benign course, there are several reports of mitral valve dysfunction, stroke, and myocardial infarction. However, few reports have been published on conduction disturbances. Case summary: We encountered a case of an atrioventricular block, which is a rarely reported complication, in a 70-year-old woman who presented with heart failure. The patient's anatomy suggested a conduction disturbance caused by CCMA extending from the posterior apex of the mitral annulus to the ventricular septum. Our heart team discussed whether surgical resection should be performed. We concluded that bradycardia was the most likely cause of the current symptoms and that resection of the extensively infiltrated calcification was risky; therefore, we decided to proceed with pacemaker implantation followed by careful observation of the mass. The patient had undergone permanent pacemaker implantation and has been asymptomatic ever since. Discussion: Few reports on conduction abnormalities caused by CCMA have been published. A mass involving the left ventricular septum and posterior mitral annulus may lead to conduction abnormalities, such as a complete atrioventricular block, in the future. We suggest that careful follow-up is required for CCMA, as it has been determined that surgical intervention is not required.