Aims: Atherosclerosis accelerates with increasing age; however, young women presenting with acute coronary syndromes (ACS) have adverse outcomes compared to men despite less obstructive coronary artery disease. We sought to evaluate the in vivo plaque characteristics and composition of untreated non-culprit lesions (NCL) at two ages (<65 years old and ≥65 years old) in patients with ACS and examine the effect of sex in both groups.
Methods and results: Untreated NCLs from 697 patients with ACS were imaged with greyscale and radiofrequency intravascular ultrasound. NCL plaque morphology, burden, composition, and major adverse cardiac events (MACE) were analysed in both age groups, and a posterior sex-based sub-analysis was performed. Plaques from patients ≥65 (n=974) vs. <65 (n=2,275) years old were longer (median 12.62 mm vs. 10.75 mm, p=0.008) and had greater plaque burden (48.2% vs. 47.5%, p=0.001), necrotic core (12.5% vs. 11.0%, p=0.001) and dense calcium (5.7% vs. 4.0%, p<0.0001). Men <65 years old also had a greater number of fibroatheromas (3.0 vs. 2.0, p=0.007) and NCLs per patient (5.0 vs. 4.0, p=0.004) with larger plaque volumes (47.7% vs. 46.8%, p=0.04), and fewer fibrotic plaques (2.2% vs. 4.4%, p=0.03) than women in the same age group. These sex differences were not observed in patients ≥65 years old. The incidence of MACE during median 3.4 year follow-up did not significantly differ according to age in this study.
Conclusions: The current study confirms in vivo that, with aging, plaque burden, necrotic core and calcium content increase significantly. Moreover, gender-specific differences in the extent and composition of coronary plaque are present in patients <65 years (but not ≥65 years) of age, which suggest differential sex-related effects on atherosclerosis development and progression.