The Role of Ischemic Mitral Regurgitation in the Pathogenesis of Acute Pulmonary Edema

BACKGROUND: Acute mitral regurgitation may cause pulmonary edema, but the pathogenetic role of chronic ischemic mitral regurgitation, a dynamic condition, has not yet been characterized. METHODS: We prospectively studied 28 patients (mean +/-SD age, 65+/-11 years) with acute pulmonary edema and left ventricular systolic dysfunction and 46 patients without a history of acute pulmonary edema. The two groups were matched for all baseline characteristics. Patients underwent quantitative Doppler echocardiography during exercise. Exercise-induced changes in the left ventricular volume, the ejection fraction, the mitral regurgitant volume, the effective regurgitant orifice area, and the transtricuspid pressure gradient were compared in patients with and without acute pulmonary edema. RESULTS: The two groups had similar clinical and baseline echocardiographic characteristics. They also had similar exercise-induced changes in heart rate, systolic blood pressure, and left ventricular volumes. In the univariate analysis, patients with recent pulmonary edema had a much higher increase than did the patients without pulmonary edema in mitral regurgitant volume (26+/-14 ml vs. 5+/-14 ml, P<0.001), the effective regurgitant orifice area (16+/-10 mm2 vs. 2+/-9 mm2, P<0.001), and the transtricuspid pressure gradient (29+/-10 mm Hg vs. 13+/-11 mm Hg, P<0.001). In the multivariate analysis, exercise-induced changes in the effective regurgitant orifice area (P<0.001), in the transtricuspid pressure gradient (P=0.001), and in the left ventricular ejection fraction (P=0.02) were independently associated with a history of recent pulmonary edema. CONCLUSIONS: In patients with left ventricular systolic dysfunction, acute pulmonary edema is associated with the dynamic changes in ischemic mitral regurgitation and the resulting increase in pulmonary vascular pressure.