Is Postsystolic Shortening a Marker of Viability in Chronic Left Ventricular Ischemic Dysfunction? Comparison with Late Enhancement Contrast Magnetic Resonance Imaging

Abstract

During acute myocardial ischemia, myocardial postsystolic shortening (PSS) is considered as a sign of viability. In chronic left ventricular (LV) ischemic dysfunction, the value of PSS is less well established. In this study, PSS was compared with transmural extent of necrosis and contractile reserve in patients with chronic LV ischemic dysfunction. A total of 25 patients (20 men, mean age: 63 +/- 8 years) with LV dysfunction (mean ejection fraction: 32 +/- 10%, range: 14%-47%) and stable coronary artery disease underwent rest color Doppler myocardial imaging, low-dose dobutamine echocardiography, and late enhancement gadolinium-magnetic resonance imaging. Strain (epsilon) curves were computed in 16 segments from color Doppler myocardial imaging sequences and were compared with transmural extent of necrosis and with contractile reserve. End-systolic epsilon was defined as epsilon value at aortic valve closure, peak epsilon (epsilon-peak) as maximal epsilon value during cardiac cycle, and time to epsilon-peak as time interval between aortic valve closure and epsilon-peak. PSS was considered when epsilon-peak occurred after aortic valve closure. Of 348 analyzable segments, 212 (61%) were graded as abnormal. In dysfunctional segments, PSS was more prevalent in transmural than in nontransmural infarcted segments (96% vs 50%, P < .001) and time to epsilon-peak was correlated to transmural extent of necrosis (r = 0.69, P < .0001). In nontransmurally infarcted segments, prevalence of PSS was similar in segments with or without contractile reserve (37% vs 45%, respectively). In chronic LV dysfunction, PSS is not a specific marker of viability. These results suggest strongly that delayed myocardial shortening may be associated to scarred segments.