Heterogeneity of left ventricular remodeling after acute myocardial infarction: Results of the Gruppo Italiano per lo Studio della Sopravvivenza nell'Infarto Miocardico-3 Echo Substudy

Background: Left ventricular (LV) remodeling after acute myocardial infarction has still to be clarified in the thrombolytic era. Methods: To evaluate timing and the magnitude and pattern of postinfarct LV remodeling, a subset of 614 patients enrolled in the Gruppo Italiano per lo Studio della Sopravvivenza nell'Infarto Miocardico-3 Echo Substudy underwent serial 2-dimensional echocardiograms at 24 to 48 hours from symptom onset (S1), at hospital discharge (S2), at 6 weeks (S3), and at 6 months (S4) after acute myocardial infarction. Results: During the study period the end-diastolic volume index (EDVi) increased (P <.001) and wall motion abnormalities (%WMA) decreased (P <.001), whereas ejection fraction (EF) remained unchanged. Nineteen percent of patients showed a > 20% increase in EDVi at S2 compared with S1 (severe early dilation), and 16% of patients showed a > 20% dilation at S4 compared with S2 (severe late dilation). Independent predictors of severe in-hospital LV dilation were relatively small EDVi (odds ratio [OR] 0.961, 95% confidence interval [CI] 0.947-0.974, P = .0001) and relatively large %WMA (OR 1.030, 95% CI 1.013-1.048, P = .0005). Similarly, smaller predischarge EDVi (OR 0.975, 95% CI 0.963-0.987, P = .0001), greater %WMA (OR 1.026, 95% CI 1.008-1.045, P = .0042), and moderate to severe mitral regurgitation (OR 2.261, 95% CI 1.031-4.958, P = 0.0417) independently predicted severe late dilation. Importantly, 92% of the patients with severe early dilation did not have further dilation at S4, and 91% of patients with severe late dilation did not have in-hospital dilation. EF was unchanged over time in patients with early dilation, whereas it significantly decreased in those with late dilation. Conclusions: Although in-hospital LV enlargement is not predictive of subsequent dilation and dysfunction, late remodeling is associated with progressive deterioration of global ventricular function over time: patients with extensive %WMA and not significantly enlarged ventricular volume before discharge are at higher risk for progressive dilation and dysfunction.