Vascular assessment for transcatheter aortic valve replacement: Intravascular ultrasound compared with computed tomography

BACKGROUND: Assessment of the femoral and iliac arteries is essential prior to transcatheter aortic valve replacement (TAVR). It is critical for establishing candidacy for a femoral approach, and can help predict vascular complications. Although computed tomography angiography (CTA) is the standard imaging modality, it has limitations. OBJECTIVE: This study compared CTA with intravascular ultrasound (IVUS) in patients undergoing TAVR evaluation. METHODS: Fifteen patients undergoing pre-TAVR coronary angiography and hemodynamic assessment were recruited. Following coronary angiography, patients underwent distal aortography, bilateral iliac and femoral arteriography, and IVUS assessment. Vascular tortuosity, minimum lumen diameter, and cross-sectional area were obtained and the findings were compared with those obtained from CTA. RESULTS: Correlation between IVUS and CTA was strong for minimum luminal diameter (r≤0.62). Concordance was also strong between CTA and invasive iliofemoral angiography for assessment of tortuosity (r≤0.75). Utilizing Bland-Altman analysis, vessel diameters obtained by IVUS were consistently greater than those obtained by CTA. The angiography and IVUS strategy was associated with a lower overall mean contrast utilization (29 cc vs 100 cc; P<.001), reduced mean radiation exposure (527 mGy vs 998 mGy; P≤.045), and no significant difference in mean test duration (13.3 minutes vs 10 minutes; P≤.12). CONCLUSIONS: For femoral and iliac arterial assessment prior to TAVR, IVUS is a viable alternative to CTA with comparable accuracy, and the potential for less contrast use and less radiation exposure. IVUS is also a valuable adjunct to CTA in patients with borderline femoral access diameters or considerable CTA artifacts.