Two-Dimensional Strain for the Assessment of Left Ventricular Function in Low Flow–Low Gradient Aortic Stenosis, Relationship to Hemodynamics, and Outcome

Abstract

Background— Decision making in patients with low flow–low gradient aortic stenosis mainly depends on the actual stenosis severity and left ventricular function, which is of prognostic importance. We used 2-dimensional strain parameters measured by speckle tracking at rest and during dobutamine stress echocardiography to document the extent of myocardial impairment, its relationship with hemodynamic variables, and its prognostic value. Methods and Results— In 47 patients with low flow–low gradient aortic stenosis, global peak systolic longitudinal strain (PLS) and peak systolic longitudinal strain rate (PLSR) were analyzed. PLS and PLSR at rest and peak stress were −7.56±2.34% and −7.41±2.89% ( P =NS) and −0.38±0.12 s −1 and −0.53±0.18 s −1 ( P <0.001), respectively. PLS and PLSR inversely correlated with left ventricular ejection fraction at rest ( r s =−0.52; P <0.0001 and −0.38; P =0.008) and peak stress ( r s =−0.39; P =0.007 and −0.45; P =0.002). The overall 2-year survival rate was 60%. Univariate predictors of survival were peak stress left ventricular ejection fraction ( P =0.0026), peak stress PLS ( P =0.0002), peak stress PLSR ( P <0.0001), and N-terminal pro–B-type natriuretic peptide ( P <0.0001). Three hierarchically nested multivariable Cox regression models were constructed—model 1: The Society of Thoracic Surgeons score as an indicator of clinical risk (area under the receiver operating characteristic=0.59); model 2: model 1+N-terminal pro–B-type natriuretic peptide and peak stress left ventricular ejection fraction (area under the receiver operating characteristic=0.83; incremental P <0.0001); model 3: model 2+peak stress PLSR (area under the receiver operating characteristic=0.89; incremental P =0.035). Conclusions— In patients with low flow–low gradient aortic stenosis, 2-dimensional strain parameters are strong predictors of outcome. Peak stress PLSR may add incremental prognostic value beyond what is obtained from N-terminal pro–B-type natriuretic peptide and peak stress left ventricular ejection fraction. A larger study is needed to confirm these findings.