Both supraventricular and ventricular rhythm disorders are frequently observed in patients with isolated left ventricular noncompaction (IVNC). Most importantly, these patients are prone to develop life-threatening ventricular arrhythmias, which are amongst their most frequent causes of death. Data regarding risk stratification of ventricular arrhythmias, however, are scarce due to the rareness of the disease. Indeed, even invasive electrophysiological studies may be of limited value in this regard in the majority of patients. Implantable cardioverter defibrillators (ICDs) have been demonstrated to be highly effective for the prevention of sudden arrhythmic death in IVNC and should be considered in patients who are clinically judged to be at high risk for ventricular tachyarrhythmias. These include patients with a severely reduced ejection fraction as well as those with a prior history of sustained ventricular tachycardia or fibrillation, recurrent syncope of unknown etiology, or a family history of ventricular tachyarrhythmias or sudden cardiac death. This review summarizes the electrocardiographic and electrophysiological findings in patients with IVNC and discusses possibilities for risk stratification as well as the rationale for ICD implantation for the prevention of sudden cardiac death.