Lesion Guided Strategy for the Use of Bare Metal Stents in Large Coronary Vessels

Abstract

Methods: Subjects greater than one year post implantation of a balloon expandable aortic valve underwent MDCT. Geometry of the stent frame was assessed for circularity, minimum (Dmin) and maximum (Dmax) external diameter and expansion ratio at three levels: ventricular, mid and aortic. Circularity was defined as an eccentricity index (EI) of less than 0.1 (EI = 1−Dmin/Dmax) and expansion ratio as a percentage of themeasured short axis derived area divided by the expected area. Results: Thirty-seven patients underwent MDCT at an average 2.7 years (987 days) post implantation (range 1.0–4.0 years) including 26 Edward Sapien, six Sapien XT and five Cribier Edwards valves. 110 of 111 (99%) segments in the 37 valveswere circular. Thewas no difference in circularity between valve type (p= 0.66) or from the ventricular to aortic aspect of the frame (p= 0.54). The mean external diameter of the 23 and 26mm valves was 23.4± 1.0mm and 25.9± 0.9mm, respectively. The average expansion ratio was 104.1± 7.5% with a significant increase from the ventricular to aortic level (100.7% vs 108.5%, p=<0.001). There were no cases of stent frame fracture. Conclusion: Balloon expandable aortic valves have excellent rates of circularity and maintain full expansion without stent frame fracture late following implantation, thus supporting long term stent durability.