Increased aortic arch calcification in patients older than 75 years: implications for carotid artery stenting in elderly patients.

OBJECTIVE: Recent studies reveal a consistently higher periprocedural risk of stroke during carotid artery stenting in octogenarians compared with younger patients. The mechanisms accounting for this increased risk of embolization and stroke in elderly patients are poorly understood. We analyzed the calcium content and aortic arch type in a consecutive series of patients to determine whether aortic arch calcium content is related to either age or arch type classification.
METHODS: Aortic arch calcium content and arch classification were examined in consecutive patients undergoing thoracic computed tomography scans. The calcium content of the aortic arch, measured from the aortic root to the descending thoracic aorta at the level of the carina, was determined by using a coronary calcium score grade. The aortic arch classification was determined by using two-dimensional and multiplanar image reconstructions. Linear regression and analysis of variance were used to determine the effect of age, arch classification, and patient comorbidity on aortic arch calcium content.
RESULTS: The computed tomography scans of 94 patients were analyzed. There was a positive correlation between age and aortic arch calcium content; the mean calcium score (Agatston units) for patients increased by decade (age <50 years, 12.6 +/- 12.3, n = 18; age 50-59 years, 14.6 +/- 8.2, n = 21; age 60-69 years, 276 +/- 120, n = 17; age 70-79 years, 1382 +/- 366, n = 27; age > or =80 years, 3889 +/- 778, n = 11; P < .001). There was significantly more arch calcium in patients 75 years or older compared with patients younger than 75 years (2458 +/- 447 vs 145 +/- 49; P < .001). There was no effect of patient comorbidity on aortic arch calcium content. Patients with type II aortic arches were older and had a higher calcium content compared with patients with type I aortic arches (2028 +/- 546 vs 712 +/- 191; P = .01). Power analysis showed more than 99% power to detect differences between patients younger than 75 years and 75 years or older.
CONCLUSIONS: Patients 75 years of age or older have significantly more aortic arch calcification compared with younger patients. Increased arch calcium content and type II aortic arches may be markers of increased potential for embolization during endovascular manipulation that transverses the aortic arch. Preprocedural determination of aortic arch calcification and morphology may help to further stratify periprocedural carotid artery stenting risk in elderly patients.