Arrhythmias in patients with mitral valve prolapse.

Resting ECGs, exercise treadmill tests and 24-hour ambulatory ECGs were recorded and analyzed in 24 unselected patients with mitral valve prolapse. Arrhythmias were frequent. There were three distinct groups of patients, defined on the basis of total number of premature ventricular contractions (PVCs) during the 24 hours; there were no PVCs in 25%, and frequent PVCs in 50%. Complex ventricular arrhythmias, including ventricular tachycardia in five patients, were found almost exclusively in the group with frequent PVCs. Fifteen of the 24 patients demonstrated atrial premature contractions (APCs) during the 24 hours. Complex atrial arrhythmias were found among patients with infrequent, as well as those with frequent, APCs. Supraventricular tachycardia was detected in seven of these patients. The incidence of ACPs decreased during sleep in 67% of the patients and showed no change during sleep in 33%. A poor correlation was found between symptoms recorded in patient diaries and changes noted on 24-hour ECG recordings. The peak PVCs/15 min and peak ACPs/15 min during a 24-hour period of monitoring was found to be an excellent guide to the total number of PVCs and APCs occurring during that period. This permits an accurate prediction of the total number of PVCs in 24 hours after performing an exact PVC count on only 15 minutes of ECG data. Finally, the 24-hour ambulatory ECG was sensitive than the treadmill test and both were superior to the 12-lead ECG for detecting arrhythmias in these patients.