Outcome of Flow-Gradient Patterns of Aortic Stenosis After Aortic Valve Replacement: An Analysis of the PARTNER 2 Trial and Registry.

Background: Although aortic valve replacement is associated with a major benefit in high-gradient (HG) severe aortic stenosis (AS), the results in low-gradient (LG, mean gradient <40 mm Hg) AS are conflicting. LG severe AS may be subdivided in classical low-flow (left ventricular ejection fraction <50%) and LG (CLF-LG); paradoxical low-flow (left ventricular ejection fraction ≥50% but stroke volume index <35 mL/m ² ) and LG; and normal-flow (left ventricular ejection fraction ≥50% and stroke volume index ≥35 mL/m ² ) and LG. The primary objective is to determine in the PARTNER 2 trial (The Placement of Aortic Transcatheter Valves) and registry the outcomes after aortic valve replacement of the 4 flow-gradient groups.
Methods: A total of 3511 patients from the PARTNER 2 Cohort A randomized trial (n=1910) and SAPIEN 3 registry (n=1601) were included. The flow-gradient pattern was determined at baseline transthoracic echocardiography and classified as follows: (1) HG; (2) CLF-LG; (3) paradoxical low-flow-LG; and (4) normal-flow-LG. The primary end point for this analysis was the composite of (1) death; (2) rehospitalization for heart failure symptoms and valve prosthesis complication; or (3) stroke.
Results: The distribution was HG, 2229 patients (63.5%); CLF-LG, 689 patients (19.6%); paradoxical low-flow-LG, 247 patients (7.0%); and normal-flow-LG, 346 patients (9.9%). The 2-year rate of primary end point was higher in CLF-LG (38.8%) versus HG: 31.8% ( P =0.002) and normal-flow-LG: 32.1% ( P =0.05) but was not statistically different from paradoxical low-flow-LG: 33.6% ( P =0.18). There was no significant difference in the 2-year rates of clinical events between transcatheter aortic valve replacement versus surgical aortic valve replacement in the whole cohort and within each flow-gradient group.
Conclusions: The LG AS pattern was highly prevalent (36.5%) in the PARTNER 2 trial and registry. CLF-LG was the most common pattern of LG AS and was associated with higher rates of death, rehospitalization, or stroke at 2 years compared with the HG group. Clinical outcomes were as good in the LG AS groups with preserved left ventricular ejection fraction compared with the HG group.