Isolated noncompaction left ventricular myocardium and polymorphic ventricular tachycardia.

A 57-year-old woman with syncope was admitted. She had a family history of sudden death: two brothers had died suddenly at the age of 47. Transesophageal echocardiography showed numerous prominent trabeculations and deep intertrabecular recesses in the anterior and lateroapical zones. Isotopic left ventricular ejection fraction was 46%. Cardiac catheterization showed coronary arteries with no angiographic lesions. A prominent trabecular zone and deep intertrabecular recesses were seen in the anterior wall on left ventriculography. Right ventriculography was normal. The diagnosis of isolated noncompaction left ventricular myocardium was established. Continuous 24-h electrocardiographic registry showed episodes of polymorphic ventricular tachycardia. Programmed ventricular stimulation performed at the right ventricular apex with up to three extrastimuli failed to induce ventricular arrhythmias. Treatment with beta blockers was initiated, but short runs of polymorphic ventricular tachycardia persisted. A dual-chamber automatic implantable defibrillator was implanted. We discuss the physiopathology of the arrhythmia. It appears that several factors could be responsible for the malignant arrhythmias in this entity.