Low dose dobutamine echocardiography in the assessment of contractile reserve to predict the outcome of valve replacement for chronic aortic regurgitation.
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BACKGROUND: When to perform surgery for aortic regurgitation is a difficult clinical decision. Occult left ventricular (LV) dysfunction may be present in patients with minimal or no symptoms, and in some patients LV dysfunction may persist after valvular replacement. OBJECTIVES: To examine the role of preoperative low dose dobutamine echocardiography (LDDE) in predicting postoperative outcome in patients who had aortic valve replacement for aortic regurgitation. PATIENTS AND METHODS: The study group comprised 16 patients (15 men, aged 48 +/- 15 years) undergoing elective surgery for aortic regurgitation. Preoperative echocardiograms were obtained in the resting state and during dobutamine infusion at 7.5 micrograms/kg/min. Complete recovery was defined by normalization of LV size and function, and the absence of symptoms at the six-month follow-up visit. Patients with complete recovery (group 1) and without complete recovery (group 2) were compared in relation to their echocardiographic parameters at rest and during LDDE. RESULTS: Of 16 patients in the study, nine were in group 1 and seven were in group 2. Age, functional class and LV end-diastolic dimensions were similar between the two groups. Group 1 patients had a smaller preoperative LV end-systolic dimension index (22.4 +/- 3.3 versus 29.9 +/- 5.9 mm/m2, P < 0.05) and a higher preoperative ejection fraction (53 +/- 8% versus 37 +/- 13%, P < 0.01). Dobutamine infusion augmented the difference in ventricular size and function between patients in group 1 and those in group 2 (LV end-systolic dimension index 18.9 +/- 3.9 mm/m2 versus 28.8 +/- 7.1 mm/m2, P < 0.01; ejection fraction 61 +/- 7% versus 41 +/- 12%, P < 0.01). CONCLUSIONS: Dobutamine accentuates differences in ventricular size and function between those with and without subsequent complete recovery following valve surgery. Because preoperative ejection fraction during LDDE is highly predictive of postoperative ejection fraction, LDDE may have a role in predicting the clinical outcome of patients following aortic valve replacement for aortic regurgitation.