Increased heart rate and shortening of the coupling intervals of the first cycles before the tachycardia are due to a change in the vagosympathetic balance with an increased sympathetic tone. This increase appears to be the main determinant of the ventricular tachycardia in this disease in contrast to the multifactorial origin of ventricular tachycardia due to coronary heart disease. It should be considered in patients participating in strenuous athletic activities.