Noninvasively-determined Diastolic Stiffness is Abnormal during Exercise, but not at Rest, in Patients with Apical Hypertrophic Cardiomyopathy

Abstract

Background: The ratio of mitral inflow (E) and annular velocity (E') to stroke volume (E/E'/SV) has been used as an index of diastolic elastance (Ed). However, its change during exercise has not been evaluated. We hypothesized that Ed values obtained during exercise would be abnormal in patients with apical hypertrophic cardiomyopathy (ApHCM). Methods: Ed was measured at rest and during graded supine bicycle exercise (25 Watts, 3 minute increments) in 15 patients with ApHCM (12 male; mean age, 57 years) and in 15 age- and gender-matched control subjects. Results: Ed was not significantly different at rest and during 25 W of exercise. However, Ed was significantly higher at 50 W of exercise in patients with ApHCM compared to control subjects (0.21±0.05 vs. 0.15±0.04 cm/s, p=0.0059). There was significant positive correlation between the magnitude of change in proBNP levels during exercise and the change of Ed from rest to 50 W of exercise (r2=0.69, p<0.0001). Conclusion: Noninvasively-determined Ed was similar at rest and during mild exercise between patients with ApHCM and control subjects. However, Ed was significantly higher during moderate exercise in ApHCM patients, suggesting a dynamic change in LV stiffness during exercise in these patients.