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

BACKGROUND

ST-segment depression is common in patients with hypertrophic cardiomyopathy (HCM). However, it is not clear whether exercise-induced ST-segment depression in patients with HCM and patent coronary arteries is associated 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 radionuclide 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 had >/=0.1 mV ST-segment depression.

RESULTS

Exercise duration, blood pressure, heart rate, and rate-pressure product during exercise did not differ between the 2 groups. End-diastolic volume 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, whereas in group D it increased. As a result, the left ventricular ejection fraction in group D decreased from 70% +/- 7% to 59% +/- 15% (P <.0001), whereas ejection fraction in group N increased from 65% +/- 8% to 71% +/- 11% (P =.0002). There was a strong correlation between exercise-induced ST-segment depression and changes in ejection fraction from rest to peak exercise (P <.0001).

CONCLUSIONS

These results suggest that the exercise-induced ST-segment depression seen in patients with nonobstructive HCM is associated with systolic dysfunction during exercise.