Abstract 18212: Relationship Between Aortic Distensibility and Coronary Blood Flow in Patients with Ascending Thoracic Aortic Aneurysm

Abstract

Introduction: We have observed coronary slow flow in patients with aortic aneurysms in the absence of coronary artery disease (CAD). Other observations have identified that aortic wall distensibility influences coronary blood flow. In order to further evaluate this phenomenon, we sought to study the relationship between aortic distensibility and coronary blood flow among the patients with ascending thoracic aortic aneurysms (ATAA). Methods: Evaluation of consecutive patients referred for surgical repair of ATAA who had non- obstructive CAD (<40% stenosis) as evaluated by coronary angiography. Aortic distensibility was calculated from aortograms using the formula D = 2 x (change in aortic diameter) / (diastolic aortic diameter) x (change in aortic pressure). Coronary blood flow was measured in all major coronary arteries by calculating TIMI frame count. Spearman rank correlation test was performed to evaluate the correlation between aortic distensibility and TIMI frame counts for the three major coronary arteries. Results: Out of 96 patients with angiographic slow flow, 89 (92.7%) patients had involvement of the ascending aorta with or without arch and/or descending aorta and non-obstructive CAD. Analysis of the 89 ATAA patients showed a significant correlation between decreased ascending aortic distensibility and prolonged TIMI frame count in all the three coronary arteries. Correlation coefficient between ascending aortic distensibility and LAD flow is r = -0.23, p = 0.03, LCX is r = -0.28, p = 0.007, RCA is r = -0.30, p = 0.005. A significant inverse correlation, r = -0.23, p = 0.04 is also observed between aortic arch distensibility and LAD flow. Conclusion: As the distensibility of the aorta decreases in patients with thoracic aortic aneurysm, the coronary blood flow also decreases. Our study for the first time shows that among the patients with thoracic aortic aneurysms, aortic distensibility does impact coronary blood flow in the absence of significant CAD, possibly through alteration in coronary blood flow mechanics and microvascular dysfunction. The clinical impact of this finding warrants further studies.