Sex differences in morphology of coronary artery plaque assessed by intravascular ultrasound.

BACKGROUND: Results of autopsy studies have suggested that there are sex differences in morphology of coronary-artery plaques, but these differences have yet to be adequately evaluated in vivo. DESIGN AND METHODS: We performed preintervention intravascular ultrasound (IVUS) measurements on coronary plaques in a consecutive series of 76 men and 30 women with unstable angina pectoris. Both the target lesion and an adjacent reference site were evaluated. Arterial, plaque, and luminal areas were measured by planimetry. Plaques were classified as either calcified or uncalcified, and relative density of plaque was quantitatively assessed by videodensitometry, using a linear gray scale normalized with respect to density of adventitia. RESULTS: Although women were older than men (mean age 55.0 +/- 10.9 versus 60.4 +/- 12.2 years, P = 0.02), their target lesions were less dense (74.6 +/- 23.4 versus 86.2 +/- 22.2% of adventitial density, P = 0.02) and less often found to be calcified (20.0 versus 38.2%, P = 0.05). Similarly, reference sites in female subjects were less dense (77.6 +/- 15.3 versus 97.1 +/- 19.4% of adventitial density, P = 0.01). There was no sex difference in the severity of coronary stenosis. CONCLUSIONS: Both qualitative and quantitative sex differences in in-vivo morphology of coronary plaques morphology were detected by IVUS measurement. Plaques in women appear less videodense and are less often calcified than are those in men. Future studies employing sequential IVUS examinations are needed in order to determine whether these morphologic differences relate to a delay in initiation of plaques, slower progression of plaques, or other sex-specific modulators of plaque composition.

Pathologic validation of a new method to quantify coronary calcific deposits in vivo using intravascular ultrasound.

Current methods of calcium quantification by intravascular ultrasound (IVUS) measure the arc of calcium using the cross-sectional image at the lesion and at the reference site while neglecting calcium elsewhere. Calcium at these sites may not adequately represent the extent of total epicardial coronary calcium. We devised a new method to quantify calcium as a percentage of the coronary luminal surface. This study examines whether this new method accurately reflects coronary calcium determined by histology. Seventeen postmortem coronary arteries were pressure-fixed and imaged by IVUS using a motorized pullback device. Total plaque-luminal circumferential length and calcified plaque-luminal circumferential length were measured from serial cross-sectional IVUS images every 1 mm. With use of Simpson's method, the total plaque and calcified plaque surface area was then calculated. Histologic sections were stained with hematoxylin-eosin and Movat pentachrome at 3-mm intervals. Calcium was independently quantified by planimetry under light microscopy. Histologic analysis (n = 253 sections) revealed a wide range of calcium (0 to 47 mm2; mean 12 +/- 16 mm3). The IVUS-derived calcified plaque surface area was 17 +/- 23 mm2), which represented 3.1 +/- 4.1% (range 0% to 13.9%) of the total plaque surface area. The histologic and IVUS quantification of calcium by this method was strongly related (r = 0.84, p <0.0001), which was an improvement over current 2-dimensional measures of calcium arc (r = 0.41, p = 0.18). Calculation of calcified plaque surface area from sequential IVUS images appears to accurately reflect the degree of total coronary calcification.

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.