Intima-media thickness and ankle-brachial index are correlated with the extent of coronary artery disease measured by the SYNTAX score

Introduction
The extent of peripheral artery disease (PAD) measured by the ankle-brachial index (ABI) and intima-media thickness (IMT) is correlated with the complexity of coronary artery disease (CAD) in stable angina patients. However, data regarding patients with acute coronary syndromes are still lacking.

Aim
To compare coronary complexity measured by the SYNTAX score in patients with and without PAD presenting with myocardial infarction (MI).

Material and methods
Both ABI and IMT were measured in 101 consecutive patients who underwent primary diagnostic due to MI. Patients were divided into three tertile groups depending on the SYNTAX score (0–4; 5–11; 12 and more points).

Results
Mean ABI in the general population was 0.9 0.26, mean IMT was 0.8 0.3 mm and mean SYNTAX score was 7.8 5.4 points. We found significant correlations between ABI and SYNTAX score (p = 0.01), IMT and SYNTAX score (p < 0.001), and IMT and ABI (p < 0.001). The highest mean values of IMT (p < 0.001) and lowest mean values of ABI (p = 0.015) were found in patients in the highest SYNTAX score group. When analyzing receiver operating characteristics (ROC) curves, IMT had greater specificity and sensitivity than ABI.

Conclusions
Both IMT and ABI are correlated with SYNTAX score (positively for IMT and negatively for ABI values). In our study, IMT was a better predictor of SYNTAX score than ABI. Our study suggests that the higher rate of cardiovascular events in patients with PAD presenting with MI may be partially explained by greater coronary lesion complexity.