Effect of dobutamine stress on left ventricular filling in ischemic dilated cardiomyopathy - Pathophysiology and prognostic implications

OBJECTIVES The purpose of this research was to study the effect of dobutamine on left ventricular (LV) filling in ischemic cardiomyopathy (ICM) and to determine whether restrictive filling pattern (RFP) at peak stress has prognostic value. BACKGROUND The prognostic value of RFP at peak stress in ICM is unknown. METHODS A total of 69 patients with ICM were studied by Doppler echocardiography at rest and stress; RFP was defined as transmittal E:A ratio >= 1.0, isovolumic relaxation time (IVRT) < 80 ms, and E-wave deceleration time (EDT) < 120 ins. RESULTS A total of 42 of 69 had REP at rest, which reverted to non-RFP at stress in 24 (EA), but persisted in 18 (EE); 27 of 69 had non-RFP at rest and peak stress (AA). In EA, IVRT and EDT lengthened (by 43 ms and 46 ms), and tricuspid regurgitation (TR) decreased (by 26 mm Hg, p < 0.01), suggesting a fall in left atrial (LA) pressure. The stress response in AA was similar to EA. In EE, IVRT and EDT shortened (by 21 ms) and TR increased (by 13 mm Hg, p < 0.01), suggesting a rise in LA pressure. Peak aortic acceleration (LV inotropy) increased by 0.8 g in EA but only by 0.2 g in EE (difference p < 0.001). Median follow-up (interquartile range) was 34 (20 to 57) months. Three-year survival for EE, EA, and AA was 49%, 79%, and 89%, respectively (p < 0.001). Compared with AA, the hazard ratio for EE was 9.5 (p < 0.001) and for EA was 1.9 (p = 0.30). CONCLUSIONS In ischemic cardiomyopathy, persistence of restrictive filling during stress implies a striking rise in LA pressure, greatly attenuated LV inotropic response, and markedly reduced survival. Stress echocardiography uniquely identifies these high-risk patients.