2003 The prognostic significance of the "no-reflow" phenomenon and infarct size to left ventricular remodeling following ST segment elevation acute myocardial infarction

Introduction

Infarct size and no reflow phenomenon also known as microvascular obstruction (MO) have been associated with adverse left ventricular (LV) remodeling following ST segment elevation acute myocardial infarction (STEMI).

Purpose

We evaluated the relative contribution of each one of these factors in the left ventricular remodeling.

Methods

A standard cine and delayed enhanced cardiac magnetic resonance (de-CMR) was performed acutely and at 6 months in 26 patients following their first STEMI, treated with primary percutaneous intervention. LV end-diastolic (LVEDV), LV end-systolic volumes (LVESV), ejection fraction (EF), and infarct size (% of LV mass) were calculated. The presence of MO was defined as any hypoenhancement within the late-hyperenhanced areas.

Results

Mean infarct size was 24.3 ± 15% LV mass. The initial infarct size highly correlated with the final EF (r = 0.76, p < 0.001), final LVEDV (r = 0.53, p < 0.001) and LVESV (r = 0.67, p < 0.001). Eight subjects (33%) had MO on ce-CMR images. Patients with MO had significantly larger LVEDV, LVESV and lower EF at baseline and at 6 months. Additionally, they also had larger initial infarct sizes. However, by multiple linear regression analysis, infarct size was the only independent predictor of final EF (B = -0.76, R² = 0.58, p < 0.001) and final LVESV (B = 0.67, R² = 0.45, p < 0.001). Table 1.

Table 1 Infarct size and MO phenomenon have been associated with adverse ventricular remodeling following STEMI. The relative contribution of these factors is unknown. Infarct size appears to be a stronger determinant of final ejection fraction and left ventricular volumes.

Conclusion

No-reflow or MO phenomenon is more often seen in patients with large infarct sizes. Both extensive infarction and the presence of microvascular obstruction are associated with adverse left ventricular remodeling. However, infarct size appears to be a stronger determinant of final ejection fraction and left ventricular volumes.