Abstract 12716: Delayed Onset of Contraction Determined by Activation Imaging is a Sensitive Parameter in Detecting Myocardial Ischemia
Background: Activation Imaging (AI) is a novel imaging technique which can evaluate the onset of regional myocardial contraction on the basis of strain profiles derived from 3-dimentional (3D) speckle tracking echocardiography. Time from QRS onset to 30% value of peak strain during a cardiac cycle (T-30%) determined by AI has been used for assessing delayed contraction in dyssynchrony. Because delayed contraction should be observed in myocardial ischemia, we investigated the feasibility of T-30% in detecting ischemia.
Methods: 3D full-volume images (volume rate: 34.4 vps) were acquired by ArtidaTM (Toshiba) at baseline, during flow-limiting stenosis (mean 52.1 ± 17.8% flow reduction), and complete occlusion of the left circumflex coronary artery in 11 dogs. T-30% was analyzed in the risk area, and peak systolic strain (ε-sys), time to early systolic lengthening (T-ESL) and time to post-systolic shortening (T-PSS) were measured as conventional parameters. T-30%, T-ESL and T-PSS were corrected by the R-R interval. All parameters were derived from area strain (ie, area change ratio). The diagnostic accuracy for detecting ischemia was assessed by the receiver operating characteristics (ROC) curve analysis.
Results: ε-sys, T-ESL and T-PSS were significantly changed during occlusion compared with baseline (p ≤ 0.01), but not during stenosis. On the other hand, T-30% was significantly prolonged not only during occlusion (p ≤ 0.001) but also during stenosis (p ≤ 0.05). Areas under the curve (AUC) of the ROC analysis were almost similar among all parameters during occlusion. During stenosis, however, the AUC of T-30% was significantly larger than that of T-ESL and T-PSS (p ≤ 0.05), and tended to be larger than that of ε-sys (figure).
Conclusion: T-30% could identify ischemic myocardium with limited coronary flow as well as with complete occlusion demonstrating better diagnostic accuracy than other parameters. AI may be useful for detecting myocardial ischemia.
- © 2013 by American Heart Association, Inc.