Cumulative exercise-induced left ventricular systolic and diastolic dysfunction in hypertrophic cardiomyopathy.

The phenomenon of cumulative exercise-induced left ventricular function impairment was studied in 40 patients with non-obstructive hypertrophic cardiomyopathy with resting normal left ventricular function and no increase in ejection fraction on exercise. All patients underwent two symptom-limited exercise tests one-hour apart. Cumulative myocardial dysfunction was seen in 13 patients (group I) but not in the remaining 27 patients (group II). During follow-up, group I showed more commonly than group II a deterioration in symptoms (67% vs 22%, P=0.025) and left ventricular function (50% vs 9%, P=0.019). In conclusion, cumulative exercise-induced myocardial dysfunction can occur in hypertrophic cardiomyopathy and may be associated with clinical deterioration and worse outcome.