Role of CT-derived global longitudinal strain in identifying left ventricular dysfunction in patients with severe aortic stenosis and preserved left ventricular ejection fraction

Abstract Introduction In patients with severe aortic stenosis, LVEF <50% is a current class 1 indication for aortic valve replacement. There are however studies showing increased mortality in patients with asymptomatic severe aortic stenosis and LVEF between 50-59% [1, 2]. Global longitudinal strain (GLS) has emerged as a more sensitive predictor of systolic dysfunction than ejection fraction in a wide number of cardiac diseases [3]. Purpose The aim of our study was to analyze left ventricular global longitudinal strain (GLS) by cardiac computed tomography (CT) in patients with severe aortic stenosis. We hypothesized that a larger portion of patients with LVEF 50-59% have signs of systolic dysfunction by GLS as compared to patients with LVEF ≥60%. Methods We identified 238 patients (median age 81, 51.3% females) with severe aortic stenosis, assessed by cardiac CT before undergoing transcatheter aortic valve replacement at Uppsala University hospital between 2016-2019. Patients in atrial fibrillation was excluded due to suboptimal image quality. Left ventricular mass index (LVMi), EF and peak GLS were calculated. The patients were divided into three groups based on LVEF (Reduced LVEF <50%, Low-Normal LVEF 50-59% and Normal LVEF ≥60%) and compared with each other regarding GLS, biomarkers and background variables. The cut off for significantly reduced GLS was set at <16%, in accordance with recently proposed criteria [4]. Results As expected GLS was significantly reduced in all patients with LVEF <50%. Among patients with Low-Normal LVEF, 62.3% had significantly reduced GLS as compared to only 3.8% patients with Normal LVEF >60% (p < 0.001). Median GLS in Low-Normal LVEF was 15.5% (IQR 14.1 - 17.4) as compared to 20.2% (IQR 18.4 - 21.9) in Normal LVEF (p < 0.001). Patients with Low-Normal LVEF had a significantly higher LV mass as compared to patients with Normal LVEF (median LVMi 85.8 g/m² vs. 75.8 g/m², p < 0.001). NT-pro-BNP was significantly higher in patients with Low-Normal LVEF compared to Normal LVEF (median 1130 vs. 664 ng/l, p = 0.003). Conclusions Almost two third of patients with severe aortic stenosis and lower range of normal LVEF (50-59%) had abnormally reduced GLS, reflecting systolic LV dysfunction, which was uncommon among those with LVEF >60%. Patients with LVEF 50-59% also presented with higher LV mass index and higher levels of NT-pro-BNP than patients with normal LVEF >60%, reflecting hypertrophic response of the myocardium to pressure overload which over time may lead to progressive myocardial decompensation. LVEF in the range of 50-59% might be an early sign of LV decompensation in severe aortic stenosis.