Incremental Prognostic Value of Novel Left Ventricular Diastolic Indexes for Prediction of Clinical Outcome in Patients With ST-Elevation Myocardial Infarction

This study examined the prognostic value of novel diastolic indexes in ST-elevation acute myocardial infarction (AMI), derived from strain and strain rate analysis using 2-dimensional speckle tracking imaging. Echocardiograms were obtained within 48 hours of admission in 371 consecutive patients with first ST-elevation AMI (59.7 ± 11.6 years old). Indexes of diastolic function including mean strain rate during isovolumic relaxation (SRIVR), mean early diastolic strain rate (SRE) and mean diastolic strain at peak transmitral E wave (E) were obtained from 3 apical views. Mean early diastolic velocity from 4 basal segments by color-coded tissue Doppler imaging was measured. Indexes of diastolic filling including E/SRIVR, E/SRE, E/diastolic strain at E, and E/early diastolic velocity were calculated. The primary end point (composite of death, hospitalization for heart failure, repeat MI, and repeat revascularization) occurred in 84 patients (22.6%) during a mean follow-up of 17.3 ± 12.2 months. Mean SRIVR (p <0.001), multivessel disease (p <0.001), Thrombolysis In Myocardial Infarction grade 0 to 1 flow after percutaneous coronary intervention (p = 0.004), and left ventricular ejection fraction (p = 0.008) were independent predictors of the combined end point on Cox regression analysis. Mean SRIVR showed incremental prognostic value over baseline clinical and echocardiographic variables (global chi-square increase from 41.0 to 51.6, p <0.001). After dividing patient population based on median SRIVR, patients with SRIVR ≤0.24/second had significantly higher event rates than others (hazard ratio 2.74, 95% confidence interval 1.61 to 4.67, p <0.001). In conclusion, SRIVR was incremental to left ventricular ejection fraction, Thrombolysis In Myocardial Infarction grade 0 to 1 flow after percutaneous coronary intervention, and multivessel disease and superior to other diastolic indexes in predicting future cardiovascular events after AMI. SRIVR may be useful in identifying high-risk patients soon after AMI.