Study population, recruitment, and severe ventricular arrhythmia. A total of 160 patients with mitral valve prolapse were invited to an exercise questionnaire of which 136 patients responded. Seventeen had experienced severe ventricular arrhythmia and were interviewed about the activity performed at time of the event. ACA, aborted cardiac arrest; ICD, implantable cardioverter defibrillator; VT, ventricular tachycardia.