Abstract
Severe chronic mitral regurgitation (MR) is associated with progressive left ventricular (LV) systolic dysfunction. Both afterload reduction and beta-adrenergic blockade have been suggested as methods for preventing LV dysfunction in asymptomatic patients with MR and normal LV function, who are therefore not yet candidates for surgical intervention. The objective of this study was to determine if afterload reduction reduces progression of LV dysfunction in patients with severe MR. The reports of echocardiographic studies performed 20 ±14 months apart were compared in a retrospective cohort of 134 asymptomatic patients with moderate-severe chronic MR and baseline ejection fraction (LVEF) >50%. Groups were defined by exposure to any afterload-reducing drug: Group 0, no exposure; Group 1, exposure beginning after the first echocardiogram; and Group 2, drug exposure beginning before the baseline echocardiogram. The groups differed importantly only in treatment duration. In 72 patients not exposed to beta-adrenergic blockade, LVEF decreased by a relative —3.2% in Group 0, while Group 1 increased by 3.4% and Group 2 increased by 5.1%, p <0.01. Among 62 patients exposed to beta-adrenergic blockade, LVEF consistently worsened (Group 0, 4.8%; Group 1, —3.3%; Group 2, —1.7%; p = 0.71) compared to the 72 patients without beta-adrenergic blockade. In a multivariate model that included treatment duration and exposure to other medications, the beneficial effect of afterload reduction (p <0.03) and the deleterious effect of beta-adrenergic blockade (p < 0.02) were significant. Afterload reduction halted or reversed the progressive worsening of left ventricular function while beta-adrenergic blockade had a deleterious effect.
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