Aims: Differentiation between necrotic and viable myocardium is difficult in the setting of acute myocardial infarction (MI). Post-systolic shortening (PSS) has been proposed as a marker of recovery after revascularization, but has not previously been assessed in patients with NSTEMI prior to revascularization. In this study, we aimed to examine the relation between PSS and improvement of contractile function after successful revascularization.
Methods and results: Thirty-five patients with non-segment elevation MI and regional systolic dysfunction were examined immediately prior to revascularization, and at follow-up 9 ± 3 months after successful revascularization. Regional systolic function was assessed by speckle tracking echocardiography as regional strain, expressed as mean peak negative longitudinal strain in segments supplied by the culprit artery. Recovery of systolic function was assessed as the difference between regional strain at follow-up and baseline (ΔStrain). Post-systolic shortening was defined as shortening in diastole beyond minimum systolic length. By multivariate regression analysis, several other variables that may affect viability were also assessed. Post-systolic shortening was observed in 32 patients (91%), mean -1.9 ± 1.4%. Mean ΔStrain was -3.3 ± 2.9%. After adjustment for baseline systolic function, PSS (β = 0.77, P= 0.022), and angiographic severity were independent predictors of viability by multiple regression analysis. Interestingly, troponin T was not a significant predictor.
Conclusions: Post-systolic shortening is associated with improved myocardial function after revascularization in patients with acute MI. It predicts long-term systolic function, and provides information on the potential benefit of the procedure.