Objective: The clinical significance of an intramural course (or bridging) of the coronary artery remains controversial. We investigated the relationship between intramural coronary arteries (ICAs) and coronary stenosis and prognosis of subjects with ICA.
Methods and results: ICA and coronary stenosis were assessed by multidetector computed tomography coronary angiography. ICAs in the left anterior descending artery were studied, which were further classified as superficial (≤2 mm) or deep type (>2 mm). Coronary stenosis was classified as nonstenosis, insignificant stenosis (<50%), and significant stenosis (≥50%). A total of 261 subjects with ICA in left anterior descending artery were identified from 2318 enrolled subjects. Most of the ICAs (66.3%) were superficial. ICA was positively associated with insignificant stenosis, and the odds ratios were 2.055 (95% confidence interval, 1.405-3.007), 3.314 (1.818-6.039), and 1.640 (1.036-2.597) for overall, deep, and superficial ICA (all P<0.05), respectively. In the case of significant stenosis, ICA was negatively associated, and the odds ratios were 0.555 (0.416-0.739) and 0.413 (0.288-0.590) for overall and superficial ICA (both P<0.05), respectively, and 0.985 (0.611-1.588; P>0.05) for deep ICA type. The depth and location of ICA correlated with stenosis. The major cardiac events, including cardiovascular death, myocardial infarction, and revascularization, were recorded during 3-year follow-up. ICA predicted a lower incidence of major cardiac events, especially superficial type; the adjusted hazard ratios were 0.585 (0.375-0.911; P=0.018) and 0.535 (0.300-0.954; P=0.034) for total and superficial type, respectively.
Conclusions: ICA, especially deep type, is positively associated with insignificant stenosis proximal to ICA. Meanwhile, ICA, especially superficial type, is negatively associated with significant stenosis proximal to ICA and predicts a better prognosis not only in normal subjects but also in patients with coronary artery disease.