The arrhythmogenic substrate--diagnostic and therapeutic implications: hypertrophic cardiomyopathy.

Hypertropic cardiomyopathy provides an important model for the study of mechanisms of sudden death. Initiating factors for sudden cardiac death may include sinus tachycardia and paroxysmal supraventricular arrhythmias. The haemodynamic effects of such triggers may be modulated depending on the patients exercise haemodynamics, peripheral vasomotor control and autonomic function. Myocardial disarray provides the underlying histological substrate for the lethal ventricular arrhythmias that represent the final common pathway. Attempts at individual risk stratification for sudden cardiac death using conventional risk factors and non-invasive techniques such as Holter monitoring identify a large group of patients, many of whom will not experience sudden cardiac death. Conventional electrophysiological methods such as programmed ventricular stimulation do not add to risk stratification inducing a variety of non-sustained or non-specific ventricular arrhythmias. A novel electrophysiological technique described in this article offers more promise in this regard.