Sex differences in coronary artery size assessed by intravascular ultrasound

BACKGROUND: Women have worse outcomes after myocardial infarction and coronary revascularization. The explanations are likely multifactorial but may include smaller coronary artery size. Smaller luminal diameter has been confirmed angiographically; however, because of possible confounding effects of coronary remodeling, angiographically silent atherosclerosis, and body size, it is unclear if there is a true sex influence on arterial size. METHODS: We performed intravascular ultrasound on left main (LM) and proximal left anterior descending (LAD) coronary artery segments that were free of significant atherosclerosis in 50 men and 25 women. Arterial and luminal areas were measured by planimetry and corrected for body surface area. We evaluated associations between sex and coronary dimensions with univariate and then multiple linear regression analyses. RESULTS: Mean uncorrected LM and LAD arterial areas were smaller in women than in men (21.53 vs 26.95 mm(2), P <.001, and 14. 68 vs 19.94 mm(2), P =.002, respectively), as were mean LM and LAD luminal areas (15.94 vs 18.79 mm(2), P =.020, and 10.13 vs 12.71 mm(2), P =.036, respectively). In multivariate models accounting for body surface area and controlling for other factors, sex independently predicted corrected LM and LAD arterial area. In analyses that additionally controlled for plaque area, sex independently predicted corrected LAD luminal area. CONCLUSIONS: LM and LAD arteries are smaller in women, independent of body size. This suggests an intrinsic sex effect on coronary dimensions. Future studies should investigate underlying mechanisms because they may lead to novel therapeutic strategies and improved outcomes for women with coronary artery disease.