Early systolic lengthening by speckle tracking echocardiography predicts outcome after coronary artery bypass surgery

BACKGROUND: Early systolic lengthening (ESL), a paradoxical stretch of myocardial fibers, has been linked to loss of myocardial viability and contractile dysfunction. We assessed the long-term prognostic potential of ESL in coronary artery bypass graft (CABG) patients. METHODS: We retrospectively included patients (n = 709; mean age 68 years; 85% men) who underwent speckle tracking echocardiography (median 15 days) prior to CABG. Endpoints were cardiovascular death (CVD) and all-cause mortality. We assessed amplitude of ESL (%), defined as peak positive strain, and duration of ESL (ms), determined as time from Q-wave on the ECG to peak positive strain. We applied Cox models adjusted for clinical risk assessed as EuroSCORE II. RESULTS: During median follow-up of 3.8 years [IQR 2.7-4.9 years], 45 (6%) experienced CVD and 80 (11%) died. In survival analyses adjusted for EuroSCORE II, each 1% increase in amplitude of ESL was associated with CVD (HR 1.35 [95%CI 1.09-1.68], P = 0.006) and all-cause mortality (HR 1.29 [95%CI 1.08-1.54], P = 0.004). Similar findings applied to duration of ESL (per 10ms increase) and CVD (HR 1.12 [95%CI 1.02-1.23], P = 0.016) and all-cause mortality (HR 1.09 [95%CI 1.01--1.17], P = 0.031). The prognostic value of ESL amplitude was modified by sex (P interaction < 0.05), such that the prognostic value was greater in women for both endpoints. When adding ESL duration to EuroSCORE II, the net reclassification index improved significantly for both CVD and all-cause mortality. CONCLUSIONS: Assessment of ESL provides independent and incremental prognostic information in addition to the EuroSCORE II for CVD and all-cause mortality in CABG patients.