Association Between DOAC Exposure and Lower-Extremity Arterial Calcification: A Propensity-Matched Exploratory CT Study

Background: Lower limb arterial calcification (LLAC) is a robust imaging biomarker of peripheral artery disease (PAD) severity. Vitamin K antagonists are presumed to accelerate cardiovascular calcification. Direct oral anticoagulants (DOACs) may influence vascular calcification differently, but lower limb data are limited. Methods: We performed a single-center retrospective cross-sectional study comparing LLAC on clinically acquired non-contrast CT between DOAC users and controls without anticoagulation. Patients were propensity score-matched 1:1 (48 DOAC vs. 48 control; n = 96) using baseline clinical covariates. Associations between LLAC scores and perioperative or cardiovascular events were assessed. Segment-specific LLAC was quantified on non-contrast CT and normalized for arterial segment length. A prespecified exposure–duration sensitivity analysis compared the outcomes in patients with ≥5 years of continuous DOAC therapy (n = 22) versus matched controls. Results: In the matched cohort, total LLAC scores did not differ significantly between DOAC and control groups (infrarenal aorta: median 7596.0 vs. 8637.0 (p = 0.487), iliac segment: median 5689.5 vs. 5193.5 (p = 0.602). However, in patients with ≥5 years of DOAC use, LLAC scores were significantly lower in proximal segments: infrarenal aorta median 5593.5 vs. 11,185.0 (p = 0.001997) and iliac arteries 5624.5 vs. 11,501.0 (p = 0.001867)). Higher LLAC was associated with major adverse cardiovascular events (such as myocardial infarction, stroke, or significant bleeding) in controls (p = 0.0023) but not in DOAC-treated patients. Conclusions: In this propensity-matched, cross-sectional CT study, long-term DOAC exposure was associated with lower proximal LLAC scores in a small duration-defined subgroup, while the primary matched analysis showed no overall difference in total LLAC scores. Because baseline (pre-DOAC) imaging was unavailable and residual confounding/survivor bias is possible, these findings should be considered hypothesis-generating and require prospective validation. The cohort reflected a mixed lower-extremity vascular population rather than exclusively classic chronic atherosclerotic PAD, which may limit biological interpretation and generalizability.