Natural History of Paradoxical Low Gradient "Severe" Aortic Stenosis
Background—Up to 30% of patients with severe aortic stenosis (SAS, indexed aortic valve area <0.6 cm2/m2), present with low transvalvular gradient (LG) despite a normal left ventricular ejection fraction (LVEF). Presently, there is intense controversy as to the prognostic implications of such findings. Accordingly, the aim of the present work was to compare the natural history of patients with paradoxical (P)LG-SAS or high gradient (HG)-SAS.
Methods and Results—We prospectively studied 349 patients with SAS and preserved LVEF. Patients were categorized into HG-SAS (n=144) and PLG-SAS (n=205) according to mean transvalvular gradient (mean gradient > or ≤ 40 mmHg). Primary end-points were all causes mortality and echocardiographic disease progression. To evaluate natural history, patients undergoing aortic valve replacement were censored at the time of surgery (n=92). During a median follow-up of 28 months, 148 patients died. Kaplan Meier survival curves showed better survival in PLG-SAS than in HG-SAS, both in the overall population (48 vs 31%, p<0.01) and in the asymptomatic subgroup (59 vs 35%, p<0.02). In asymptomatic patients, Cox's analysis identified age, diabetes, left atrial volume and mean gradient as independent predictors of death. Finally, at last echocardiographic follow-up, PLG-SAS demonstrated significant increases in mean gradient (from 29±6 to 38±11 mmHg, p<0.001).
Conclusions—Our study indicates that PLG-SAS is a less malignant form of aortic stenosis than HG-SAS, as their spontaneous outcome is better. We further demonstrated that patients with PLG-SAS are "en route" toward the more severe HG-SAS form, as the majority of them evolve into HG-SAS overtime.
- Received November 18, 2013.
- Accepted April 24, 2014.