OBJECTIVEto explore the feasibility of evaluating viable myocardium with two-dimensional strain imaging combined with adenosine stress echocardiography.

METHODSacute myocardial infarction and reperfusion model was made by ligating anterior descending coronary artery for 90 minutes followed by 120-minute reperfusion in 15 healthy mongrel dogs. Images were acquired at baseline and after reperfusion. Adenosine was then infused and image acquisition repeated. Regional peak-systolic strain in radial, circumferential and longitudinal motion on anterior wall and anterior septum were measured. TTC staining served as a "gold standard" to define viable and nonviable myocardium. The ratio of infarct area (S(N)) to total area (S) was calculated and viable myocardium was defined with S(N)/S ≤ 50%.

RESULTSat baseline, RS(peak sys), CS(peak sys) and LS(peak sys) were similar between viable (n = 37) and nonviable myocardial segments (n = 53) and significantly decreased after reperfusion in both viable and nonviable myocardial segments. Compared with values obtained after reperfusion, LS(peak sys) and RS(peak sys) remained unchanged in nonviable myocardial segments and significantly increased in viable myocardial segments after adenosine (P < 0.05). Post adenosine RS(peak sys) was negatively correlated with S(N)/S and CS(peak sys) and LS(peak sys) were positively correlated with S(N)/S. With ΔRS(peak-sys) (before and after adenosine) ≥ 13.5%, the sensitivity was 83.8% and specificity was 83.0% for distinguishing viable from nonviable myocardial segment. With ΔLS(peak sys) ≥ 11% as cutoff value, the sensitivity was 78.4% and specificity was 88.7% for distinguishing viable from nonviable myocardial segment. Combining ΔRS(peak sys) and ΔLS(peak sys), the sensitivity and specificity for distinguishing viable from nonviable myocardial segment were 91.9% and 79.2%, respectively.

CONCLUSIONStwo-dimensional strain imaging combined with adenosine stress echocardiography could quantitatively identify viable and nonviable myocardium.