The purpose of this review is to discuss the pathophysiology of the complicated arrhythmias or sudden cardiac death, the appropriate risk stratification and current treatment options in patients with dilated cardiomyopathy, hypertrophic cardiomyopathy and arrhythmogenic right ventricular cardiomyopathy. It is important to know possible risk factors on risk stratification for a high-risk group in each cardiomyopathy. Therapeutic strategies, including amiodarone, implantable-cardioverter-defibrillator, may contribute the prevention of sudden cardiac death.