Introduction:We sought to evaluate what clinical and echocardiographic parameters would help predict major adverse cardiac events (MACE) in patients with severe aortic stenosis, preserved ejection fraction (EF>50%) with low mean gradient (LGAS <40 mmHg) stratified by stroke volume index (SVi >or <34mL/m2).Methods:A retrospective data review of patients with asymptomatic LGAS with preserved EF was performed excluding any patients with prior AV interventions. Clinical data, standard AV echo parameters and novel indices such as valvuloarterial impedance on 243 patients (Jan 2014 - Dec 2015) were obtained. Composite MACE (Congestive heart failure, myocardial infarction, AV replacement, or death) were obtained over 3.8 +1 year after echo. Patients were stratified into normal flow low gradient severe aortic stenosis (NFLGAS, SVi ?34mL/m2) and paradoxical low flow low gradient aortic stenosis (PLGAS, SVi <34mL/m2).Results:Average age was 80.3 years (SD: 13.1). Composite MACE developed in 136 patients. Compared to non-MACE group, patients who developed MACE were more likely to be males (p=0.013), with atrial fibrillation (AF, n=51, p=0.004).Among PLGAS group(48.6%, n=118), patients who developed MACE (58.5%, n=69) were more likely to have pulmonary hypertension (PHTN, p=0.005), lower indexed aortic valve area (AVAi, p=0.04), more likely to have AF (p=0.042). Univariate predictors of MACE among PLGAS group were AF (OR 2.26; CI 1.02-4.99; p=0.044), PHTN (OR 1.56; CI 1.13-2.16; p=0.007), lower AVAi (OR 0.69; CI 0.48-0.99; p=0.044). Multivariate predictors for MACE were lower AVAi (OR 0.67; CI 0.46-0.99; p=0.043), and PHTN (OR 1.05; CI 1.02-1.09; p=0.005).Among NFLGAS(51.4%, n=125), patients who developed MACE (53.6%, n=67) were more likely to have higher AV Vmax (p=0.001), higher mean gradient (MG, p=0.001), lower AVAi (p=0.001), less likely to be females (p=0.009). Univariate predictors of MACE among NFLGAS were lower AVAi (p=0.001), higher MG (p=0.001), higher AV Vmax (p=0.001). Multivariate predictors of MACE were lower AVAi (p=0.001), higher SVi (p=0.001) and older age (p=0.019).Conclusion:This study of NFLGAS and PLGAS patients reaffirms that commonly used indices such as AVAi and PA pressure with AF could best help predict MACE in both groups.