Exercise-induced ST-segment depression and systolic dysfunction in patients with nonobstructive hypertrophic cardiomyopathy

Background ST-segment depression is common in patients with hypertrophic ca rdiomyopathy (HCM). However, it is not clear whether exercise-induced ST-se gment depression in patients with HCM and patent coronary arteries is assoc iated with changes in left ventricular function. Methods Left ventricular function was continuously evaluated in 53 patients with nonobstructive HCM during supine ergometer exercise with a radionucli de ventricular function monitor equipped with a cadmium telluride detector. On the basis of the ST-segment changes during exercise, the patients were divided into 2 groups: group N had no ST-segment depression, and group D ha d greater than or equal to 0.1 mV ST-segment depression. Results Exercise duration, blood pressure, heart rate, and rate-pressure pr oduct during exercise did not differ between the 2 groups. End-diastolic vo lume at rest and at peak exercise did not differ between groups D and N. In contrast, the end-systolic volume in group N decreased during exercise, wh ereas in group D it increased. As a result, the left ventricular ejection f raction in group D decreased from 70% +/- 7% to 59% +/- 15% (P < .0001), wh ereas election fraction in group N increased from 65% +/- 8% to 71% +/- 11% (P = .0002). There was a strong correlation between exercise-induced ST-se gment depression and changes in ejection fraction from rest to peak exercis e (P < .0001). Conclusions These results suggest that the exercise-induced ST-segment depr ession seen in patients with nonobstructive HCM is associated with systolic dysfunction during exercise.