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. Conclusion-Impaired diastolic reserve results in stress-induced increase in the left ventricular end-diastolic pressure in patients with HFNEF giving rise to exercise intolerance. (Circ Heart Fail. 2010;3:35-43.)

Background: Cardiac resynchronisation therapy (CRT) improves symptoms and exercise capacity in many patients with heart failure (HF) who have left ventricular systolic dysfunction (LVSD) and markers of dyssynchrony. LV dyssynchrony is conventionally measured at rest but the symptoms of heart failure occur predominantly on exercise. Induction or exacerbation of dyssynchrony during stress might identify additional patients who could benefit from CRT. Methods and results: Seventy-seven patients (47 with QRSd b 120 ms and 30 with QRSd N 120 ms) with heart failure due to left ventricular systolic dysfunction and 22 normal subjects underwent dobutamine stress echocardiography using colour tissue Doppler imaging. Left intraventricular dyssynchrony was measured as the standard deviation of the time to peak velocity from the onset of the QRS (Ts-SD) and the difference between the maximum and minimum time to peak velocity (Tscor-diff) in the 12 non-apical segments at rest and during peak stress. Timings were corrected for heart rate. The mean values of these indices increased with stress in both groups of patients but not in control subjects ( p b 0.001). The prevalence of conventionally-defined dyssynchrony also increased with stress. Conclusion: In patients with heart failure, the severity and the prevalence of intraventricular dyssynchrony increase with stress. Whether stress-induced dyssynchrony will identify patients who might benefit from CRT awaits further research.

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