Prognostic value of tissue Doppler Tei index after experimental myocardial infarction

Background: It has been reported that tissue Doppler imaging (TDI) derived Tei index, defined as the sum of isovolumetric contraction and relaxation time divided by ejection time, is a valuable tool in assessing combined systolic and diastolic function with a better reproducibility than pulsed Doppler Tei index. Therefore, we hypothesized that early measurement of TDI Tei index could provide prognostic survival information beyond standard systolic and diastolic echo parameters on an animal model of acute myocardial infarction (AMI). Methods: In 64 adult consecutive mice (CB57/BL6, age 10-12 weeks, weight 22.7 3g) a large AMI was created by proximal LAD ligation. Echocardiography (Sequoia 512, Acuson) was performed 48 7 hours after surgery. Left ventricular (LV) diastolic (LVED) and systolic (LVES) dimensions, LV fractional shortening (LVFS), LV ejection fraction (LVEF), LV wall motion score index (WMSI), LV E/A ratio and LV TDI Tei index were measured using a 15MHz transducer. The smallest TDI sample volume was placed at the level of the lateral side of the mitral annulus in parasternal long axis view. Systolic (Sa), early (Ea) and late (Aa) diastolic myocardial velocities were recorded from the annulus site. TDI Tei index was calculated as TI=(a-b)/b where a is the time interval from the end of Aa wave to the onset of Ea wave and b the time from the onset to the end of Sa wave. Results: High operative mortality rate of this model (12.5%) was correlated to AMI. During a follow-up of 165 11 days, 8 mice (14.28%) died. TDI Tei index was significantly lower in survivors than in deceased mice (0.47 0.09 versus 0.83 0.12, p < 0.0001). Mortality rate was significantly higher in mice with highest Tei index values (>0.15) - p < 0.0001 -. In a stepwise multivariate Cox proportional-hazard analysis including the different indices of cardiac function that were found to be independent predictors of cardiovascular mortality in the univariate analyses, a high TDI Tei index remained a significant predictor above LVEF, LV WMSI and E/A ratio (chi-square = 7.9, p = 0.003). Conclusions: Our data suggest that early assessment of TDI Tei index is a powerful predictor of mortality after AMI in mice and provides important prognostic information beyond other measurements of cardiac function.