Background: The genesis of symptoms in patients with heart failure (HF) and normal ejection fraction (HFNEF) is unclear. Most investigations of HFNEF have focused on cardiac function at rest although most of these patients are breathless only on exercise. Stress-induced impairment in systolic or diastolic function could result in these symptoms. Method and Result- Forty-one patients with HFNEF and 29 controls underwent dobutamine stress echocardiography with color tissue Doppler imaging. Wall motion score index and regional myocardial systolic velocity (Sm) were measured at and peak stress. Systolic (Sa), early diastolic (Ea), and late diastolic (Aa) mitral annular velocities were averaged over the 6 periannular sites. Mitral annular long-axis velocity was lower in the HFNEF than controls at rest. Global, regional, and long-axis systolic function did not worsen with stress in the HFNEF group. The Ea decreased and the E/Ea increased with stress in the HFNEF but not in controls. The 6-minute walk distance was shorter and negatively correlated to the E/EA ratio at rest and stress in the HFNEF group.
Conclusions: Impaired diastolic reserve results in stress-induced increase in the left ventricular end-diastolic pressure in patients with HFNEF giving rise to exercise intolerance.