Correlates and Long-Term Implications of Left Ventricular Mechanical Dispersion by Two-Dimensional Speckle-Tracking Echocardiography in Patients with ST-Segment Elevation Myocardial Infarction

Abstract

Left ventricular (LV) mechanical dispersion (LVMD), measured with speckle-tracking echocardiography (STE) after ST-segment elevation myocardial infarction (STEMI), has been proposed as a measurement of regional heterogeneity of myocardial contraction and may reflect changes in the myocardial structure (e.g., fibrosis or edema). Further insight into this parameter may aid in the risk stratification of STEMI patients. A total of 1,000 STEMI patients (77% male, 60±12years) treated with primary percutaneous coronary intervention were retrospectively analyzed. The LVMD was assessed with two-dimensional STE within 48hours following the index infarction. Patients were followed for the occurrence of all-cause mortality. After a median follow-up of 117months, 229 (23%) patients died. Nonsurvivors showed worse LV ejection fraction (43%±10% vs 48%±9%; P<.001) and global longitudinal strain (-12.0%±3.5% vs -14.2%±3.5%; P=.001) and prolonged LVMD (63 [interquartile range, 50-85] msec vs 52 [interquartile range, 42-63] msec; P<.001) compared with survivors. Increasing age, systolic blood pressure, and heart rate at discharge as well as diabetes mellitus, anterior STEMI, TIMI flow < 2, less usage of angiotensin converter enzyme inhibitors or angiotensin receptor blockers, and impaired LV global longitudinal strain were independently associated with more prolonged LVMD. On multivariable analysis, prolonged LVMD was independently associated with increased risk of all-cause mortality (hazard ratio=1.012; 95% CI, 1.005-1.018; P=.001) and had incremental value for all-cause mortality over clinical and echocardiographic parameters. In contemporary STEMI patients, prolonged LVMD was associated with various clinical and echocardiographic parameters. Prolonged LVMD was associated with worse long-term outcome.