The Association Between Abnormal Electrocardiogram Findings and the Ankle Brachial Index

Background and Objectives: Peripheral artery disease (PAD) is a common manifestation of systemic atherosclerosis associated with significant morbidity and mortality, yet it remains underdiagnosed due to limited routine screening and its often-asymptomatic presentation. Although the ankle–brachial index (ABI) is the gold standard diagnostic tool for PAD, its use may be limited in some settings because it requires specialized equipment and trained personnel. In contrast, the electrocardiogram (ECG) is widely available and routinely performed. Given that ECG abnormalities may reflect systemic cardiovascular disease, we investigated the association between ECG findings and ABI classification. Materials and Methods: This retrospective case–control study analyzed patients with and without PAD who received care from outpatient vascular clinics between March 2018 and February 2022. PAD was defined as ABI ≤ 0.9 or toe–brachial index ≤ 0.67 with abnormal pedal pulses. The most recent ECG performed within one year of ABI measurement was retrieved for each patient and classified as normal, borderline, or abnormal according to standardized guideline recommendations. The association between ECG category and ABI classification was assessed using chi-square testing and multivariable logistic regression adjusted for age and sex, with results reported as odds ratios (ORs) and 95% confidence intervals (CIs). Discriminatory performance of the ability of ECG findings to predict ABI classification was evaluated using the area under the receiver operating characteristic curve (AUROC) with 95% CI. Model calibration was assessed using the Hosmer–Lemeshow test. Results: Overall, 491 patients had paired ECG and ABI data. ECGs were categorized as abnormal (n = 345), borderline (n = 58), or normal (n = 88). The prevalence of abnormal ABI (≤0.9) was highest among patients with abnormal ECGs (45.8%), compared to borderline (34.5%) and normal ECGs (28.4%) (p = 0.0067). On multivariable logistic regression analysis adjusted for age and sex, abnormal ECG findings were associated with increased odds of abnormal ABI compared to normal ECGs (adjusted OR 2.07, 95% CI 1.24–3.46, p = 0.005), whereas borderline ECGs were not (OR 1.31, 95% CI 0.64–2.68, p = 0.455). ECG categorization demonstrated moderate discrimination (AUROC 0.73, 95% CI 0.68–0.78) and good calibration (Hosmer–Lemeshow χ² 5.0, p = 0.76) for predicting abnormal ABI. Conclusions: In this retrospective case–control study, we found an association between abnormal ECG findings and abnormal ABI. These results support the concept that clinically significant ECG abnormalities may reflect systemic atherosclerotic burden rather than isolated cardiac pathology. Given the widespread availability and low cost of ECG testing, ECG interpretation may help identify patients who warrant further investigations, including PAD screening, vascular assessment, and risk-stratification, particularly in lower-resource settings without routine access to ABI testing. Prospective, multicenter studies are needed to validate these findings.