[Prognosis of mitral valve prolapse related to the changes in the grade and ventricular arrhythmias].

Eighty-four cases with idiopathic mitral valve prolapse (MVP) were followed for 3.1 years in average (1 to 6 years). Left ventricular end-diastolic and end-systolic dimensions and/or left atrial dimension increased in 72.4% of the cases with severe grade of MVP, while in only 14.3% of the cases with mild grade of MVP during follow-up period. Incidence of ventricular arrhythmias was 70% including about 10% each of grade III, IVa, and IVb in Lown's classification. Repeated examination using 24-hour Holter monitoring showed ventricular arrhythmias of long duration in a majority of the cases, and 66.7% of the cases with III and IV in Lown's classification revealed IVa and IVb frequently including one case of sudden death occurred during follow-up period.