P1470Myocardial dysfunction index: a novel myocardial strain parameter for diagnosing myocardial ischemia

Abstract

Abstract Background and purpose Peak systolic strain (ε-sys) derived from speckle tracking echocardiography (STE) is a useful parameter for assessing regional contractile dysfunction during acute ischemia. However, low ε-sys does not always indicate myocardial ischemia because of its relatively large variation in segmental normal ranges and intervendor differences. Therefore, comparison of strain before and after an ischemic event and demonstration of a decrease in ε-sys should be necessary to confirm myocardial ischemia, which is not always possible in clinical situations. It is well known that early systolic lengthening (ESL) and post-systolic shortening (PSS) occur during acute ischemia. We hypothesized that ESL and PSS would correlate with the decrease in ε-sys and integrated analysis of ESL and PSS could be useful to diagnose the presence of myocardial ischemia. Methods 2D short-axis or 3D full-volume images were acquired by Artida at baseline, during flow-limiting stenosis (mean 50±20% flow reduction), and during complete occlusion of the left circumflex coronary artery in 22 dogs (2D-STE = 12, 3D-STE = 10).Circumferential strain was analyzed in the center of risk area, and the absolute value of peak systolic strain (ε-sys), post-systolic strain index (PSI) as a parameter of PSS, and early systolic strain index (ESI) as a parameter of ESL were measured. A new parameter, myocardial dysfunction index (MDI), which was calculated as follows: (ESL amplitude + PSS amplitude)/maximal strain amplitude during the cardiac cycle, was also calculated. The difference in ε-sys between at baseline and during ischemia (Δε-sys) was measured and the diagnostic accuracy for estimating Δε-sys < −3% was assessed by the receiver operating characteristics (ROC) curve analysis. Results During ischemia, ε-sys decreased from 19±3 to 12±6% and MDI increased from 2±4 to 27±30%. MDI was significantly correlated with Δε-sys (2D-STE: r=−0.80, 3D-STE: r=−0.83, p<0.01, respectively) (Figure). The area under the curve (AUC) of MDI for estimating Δε-sys < −3% tended to be larger than those of ESI and PSI (MDI: 0.9, ESI: 0.73, PSI: 0.85). Figure 1 Conclusions The novel parameter, MDI was correlated with the decrease in ε-sys during acute ischemia. Integrated analysis of ESL and PSS may be useful for diagnosing the presence of myocardial ischemia.