右側弁外損傷：低流量・低勾配大動脈弁狭窄症におけるリスクモデル失敗の過小評価された要因

The Society of Thoracic Surgeons Predicted Risk of Mortality (STS-PROM) score is guideline-endorsed for estimating procedural risk in aortic stenosis (AS) but tends to overestimate long-term mortality after transcatheter aortic valve replacement (TAVR). This study aimed to evaluate whether markers of right-sided extravalvular damage improve STS-PROM's performance in predicting 1-year mortality post-TAVR for patients with low-flow, low-gradient AS.

Four hundred ten patients with valve area ≤1.0 cm², stroke volume index ≤35 mL/m², and mean gradient <40 mm Hg who underwent TAVR were retrospectively stratified into low (<4%), moderate (4%-8%), and high (>8%) STS-PROM risk groups. Performance of an enhanced logistic regression model incorporating both STS-PROM and right-sided extravalvular damage (defined as moderate+ pulmonary hypertension, moderate+ tricuspid regurgitation, or right ventricular systolic dysfunction) was assessed using receiver operating characteristic curves, net reclassification index (NRI), and integrated discrimination index (IDI).

Right-sided extravalvular damage was independently associated with increased 1-year mortality (OR, 2.45; 95% CI, 1.34-4.46; P < .01). Model fit improved with its addition (Δχ² = 8.68, P < .01), and discrimination increased (IDI = 0.02, P = .01). NRI analysis showed improved survivor classification (non-event NRI = 0.10, P < .01). The largest gain was in moderate-risk patients (area under the curve, 0.46-0.67; P = .06).

Markers of right-sided extravalvular damage conferred meaningful prognostic value in low-flow, low-gradient AS by correcting the STS-PROM score's tendency to overestimate post-TAVR mortality. The added value of these markers was most pronounced in moderate-risk patients, for whom existing tools appear least reliable. These markers may improve patient selection for TAVR and merit evaluation in other severe AS phenotypes.