Abstract
AIMS: Global longitudinal strain (GLS) has become an alternative to left ventricular ejection fraction (LVEF) to determine systolic function of the heart. The absence of cut-off values is one of the limitations preventing full clinical implementation. The aim of this study is to determine a cut-off value of GLS for an increased risk of adverse events in individuals with a normal LVEF. METHODS AND RESULTS: Echocardiographic images of 502 subjects (52% female, mean age 48 ± 15) with an LVEF ≥ 55% were analysed using speckle tracking-based GLS. The primary endpoint was cardiovascular death or cardiac hospitalization. The analysis of Cox models with splines was performed to visualize the effect of GLS on outcome. A cut-off value was suggested by determining the optimal specificity and sensitivity. The median GLS was -22.2% (inter-quartile range -20.0 to -24.9%). In total, 35 subjects (7%) had a cardiac hospitalization and/or died because of cardiovascular disease during a follow-up of 40 (5-80) months. There was a linear correlation between the risk for adverse events and GLS value. Subjects with a normal LVEF and a GLS between -22.9% and -20.9% had a mildly increased risk (hazard ratio 1.01-2.0) for cardiac hospitalization or cardiovascular mortality, and the risk was doubled for subjects with a GLS of -20.9% and higher. The optimal specificity and sensitivity were determined at a GLS value of -20.0% (hazard ratio 2.49; 95% confidence interval: 1.71-3.61). CONCLUSIONS: There is a strong correlation between cardiac adverse events and GLS values in subjects with a normal LVEF. In our single-centre study, -20.0% was determined as a cut-off value to identify subjects at risk. A next step should be to integrate GLS values in a multi-parametric model.