Predicting changes in flow category in patients with severe aortic stenosis and preserved left ventricular ejection fraction on medical therapy

Background/ObjectivesControversy surrounds the prognosis and management of patients with paradoxical low-flow severe aortic stenosis (AS) with preserved left ventricular ejection fraction (LVEF). It was not certain if patients in a particular flow category remained in the same category as disease progressed. We investigated whether there were switches in categories and if so, their predictors. MethodsConsecutive subjects (n=203) with isolated severe AS and paired echocardiography (>180days apart) were studied. They were divided into 4 groups, based on their flow categories and if they progressed on subsequent echocardiography to switch or remain in the same flow category. Univariate analyses of clinical and echocardiographic parameters identified predictors of these changes in flow category. ResultsOne hundred eighteen were normal flow (SVI35mL/m(2)), while 85 were low flow on index echocardiography. In the patients with normal flow, 33% switched to low flow. This was associated with higher valvuloarterial impedance (Zva, P<.001) and lower systemic arterial compliance (SAC, P<.001) compared to index echocardiography, and predicted by higher initial Zva (optimized cutoff >4.77mmHg/mL/m(2), AUC=0.81 [95% CI:0.75-0.87, P<.001]). In patients with low flow, 25% switched to normal flow, which was associated with lower Zva and higher SAC and the switch was predicted by a higher initial mean transaortic pressure gradient. ConclusionsA significant number of patients switched flow categories in severe AS with preserved LVEF on subsequent echocardiography. Changes in flow were reflected by respective changes in Zva and SAC. Identifying echocardiographic predictors of a switch in category may guide prognostication and management of such patients.