Infrapopliteal Arterial Calcifications on Plain Film Radiographs and Association With Coronary Artery Calcification: A Retrospective Cohort Study and Suggested Screening Flowchart

BACKGROUND: Infrapopliteal arterial calcifications (IPACs) are commonly seen on radiographs. No studies have examined the association between IPACs on radiographs and coronary artery calcium scores among the general population. METHODS: This retrospective cohort study examined patients who had both a heart scan for calcium scoring and foot, ankle, heel, or tibia/fibula plain film radiographs within a year of each other. Two radiologists and three foot and ankle specialists reviewed radiographs independently followed by a consensus review. Agatston scores and demographics were recorded via chart review. Univariate and regression analyses were performed to compare rates of abnormal and severe cardiac scans among patients with and without IPACs. RESULTS: Blind concordance was achieved among five reviewers for 211 of 283 radiographs (74.5%); each reviewer scored higher than 89% compared with the consensus results. Thirty-four of 283 patients were found to have IPACs and were more likely to have a nonzero heart scan score compared with those without IPACs (91% [31 of 34] versus 55% [136 of 249]; odds ratio, 8.6; 95% confidence interval, 2.6-28.8; P < .0001). Sixty-two percent (21 of 34) of patients with IPACs had category 3 or 4 heart scores, whereas only 21% (52 of 249) of those without IPACs had category 3 or 4 heart scores (P < .0001). IPACs remained significantly associated with category 3 or 4 heart scores (odds ratio, 4.4; 95% confidence interval, 2.0-9.7; P = .0003) even after controlling for age and diabetes with logistic regression modeling. Only four of 34 patients (11.7%) had IPACs reported on their original radiology report. CONCLUSIONS: IPACs were accurately identified on radiographs by several reviewers but are often not mentioned on radiology reports. When present, IPACs are strongly associated with nonzero heart scores and severe heart scores. This finding could influence preventive cardiac care in asymptomatic patients.