Impact of flow and left ventricular strain on outcome of patients with preserved left ventricular ejection fraction and low gradient severe aortic stenosis undergoing aortic valve replacement.

The prognostic implications of flow, assessed by stroke volume index (SVi), and left ventricular (LV) global longitudinal strain on survival of patients with low-gradient severe aortic stenosis (AS) and preserved LV ejection fraction are debated. The aim of this study was to evaluate the impact of flow and LV global longitudinal strain on survival in these patients treated with aortic valve replacement (AVR). Patients with low-gradient severe AS with preserved LV ejection fraction treated with AVR (n = 134, mean age 76 ± 10 years, 50% men) were included in the present study. Aortic valve hemodynamics and LV function were assessed with 2-dimensional, Doppler and speckle-tracking echocardiography before AVR. Patients were dichotomized on the basis of low (SVi ≤35 ml/m(2)) or normal (SVi >35 ml/m(2)) flow and impaired (>-15%) or more preserved (≤-15%) global longitudinal strain. The end point was all-cause mortality. During a median follow-up period of 1.8 years (interquartile range 0.5 to 3) after AVR, 26 patients (19.4%) died. Survival was better for patients with SVi >35 ml/m(2) or global longitudinal strain ≤-15% compared with those with SVi ≤35 ml/m(2) or global longitudinal strain >-15% (log-rank p = 0.01). Atrial fibrillation (hazard ratio 5.40, 95% confidence interval 1.81 to 16.07, p = 0.002) and chronic kidney disease (hazard ratio 3.67, 95% confidence interval 1.49 to 9.06, p = 0.005) were the clinical variables independently associated with all-cause mortality. The addition of global longitudinal strain (chi-square = 19.87, p = 0.029, C-statistic = 0.74) or SVi (chi-square = 29.62, p <0.001, C-statistic = 0.80) to a baseline model including atrial fibrillation and chronic kidney disease (chi-square = 14.52, C-statistic = 0.68) improved risk stratification of these patients. In conclusion, flow and LV global longitudinal strain are independently associated with survival after AVR in patients with low-gradient severe AS with preserved LV ejection fraction.