Therapeutic implications of contractile reserve elicited by dobutamine echocardiography in symptomatic, low-gradient aortic stenosis.

BACKGROUND: In patients with heart failure, poor ejection fraction and estimated severe aortic stenosis because of a reduced aortic valve area (AVA) and low gradients, dobutamine echocardiography (DE) was proposed to distinguish afterload mismatch from primary left ventricular dysfunction. In this setting the feasibility and safety of DE and the outcome following management based on DE results were investigated.

METHODS: Forty-eight patients (mean age 73 +/- 9 years; 79% males; AVA 0.7 +/- 0.2 cm2; mean aortic gradient 22 +/- 6 mmHg; ejection fraction 0.28 +/- 0.07; NYHA functional class 2.9 +/- 0.8) underwent DE and were followed up for 24 +/- 21 months. Aortic valve replacement (AVR) was offered to patients with left ventricular contractile reserve (ejection fraction increase > or = 30% at peak DE) and fixed aortic stenosis (AVA increase < or = 0.25 cm2).

RESULTS: DE elicited a left ventricular contractile reserve in 38 patients (79%). Among these, fixed aortic stenosis was present in 28 patients, among whom 19 underwent AVR and 9 declined surgery. The 20 patients without contractile reserve or with relative stenosis (AVA increase > 0.25 cm2) were not considered eligible for surgery. During follow-up, 23 cardiovascular deaths occurred: 2/19 among operated patients, 7/9 among patients who declined surgery and 14/20 among non-eligible patients. Patients with AVR showed a significantly more favorable outcome and improved functional status as compared to the other two groups (NYHA class 1.2 +/- 0.4 vs 2.7 +/- 0.6 at baseline; p < 0.001). Conversely, non-surgical management was the strongest independent predictor of an adverse outcome (relative risk 3.6, 95% confidence interval 1.8-7.3; p < 0.0001).

CONCLUSIONS: In patients with heart failure and estimated severe aortic stenosis, DE could identify a subgroup with a left ventricular contractile reserve and fixed aortic stenosis who gained great benefit from AVR. The clinical outcome of patients who were not operated upon was unfavorable.