Feasibility of ultra-low volume contrast pulmonary arterial injection protocol for CTA in TAVI candidates with severe renal failure

Abstract Introduction Computer tomography angiography (CTA) has an important role in patient screening before TAVI. The high volumes of iodinated contrast media (CM) injected during the examination represents the main limitation of CTA with a dose-dependent association with contrast-induced nephropathy. Purpose Show the feasibility of an ultra-low-dose CM pulmonary arterial injection protocol for CTA in TAVI candidates in high risk patients with severe renal failure. Methods In our retrospective study seventy-seven (77) patients with CKD on stage 3b or worse (eGFR ≤ 45/min/1.73 m2) underwent pre-procedural CTA for TAVI-planning with a pulmonary arterial administration of CM. All CTA examinations were performed using a Dual Source 256-slice CT system. All enhanced CT acquisitions were performed using our dedicated biphasic injection protocol composed of two connected phases of contrast medium injection using different amount of CM (8, 10, 15 and 20 ml) according to BMI (<22 kg/m2; 22-24 kg/m2; 24-28 kg/m2; >28 kg/m2). The CM was administered directly into the pulmonary artery in all patients. For each examination was measured Intraluminal attenuation at thoraco-abdominal aorta and along the ilio-femoral vessels using the ROI (mean SD in HU) as objective image parameters (Picture 1). Serum creatinine and the eGFR were recorded pre-TAVI CT scan and after the procedures as reference of CM to renal function. Results CTA was successfully performed in all patients. Mean creatinine was 2.25 ± 0,76 mg/dL and mean GFR was 26.5± 8.1 mL/min/m2. Mean vessel attenuation was 352±164 HU at the aortic annulus, 238.1 ± 141,3 HU in the aortic arch and 266±168 in the iliac arteries (Picture 2). The mean image noise was 28.2 ± 7 HU in the aortic annulus, 24.4 ± 10,9 in the right external iliac artery, and 25. ± 12,8 HU in the left external iliac artery. After CTA examination, a total of 74 patients (96%) underwent TAVI. Mean CM dose administered during TAVI procedure was 150,6 ± 85,8. Three patients (3.9%) were abolished for TAVI. Postprocedural settings complications were recorded. A total of 31 patients (41%) had grade 1 paravalvular regurgitation, 10 patients (14%) grade 2. No cases of valve embolization or anulus rupture occured. No major vascular complications occured. No significant differences between creatine and eGFR pre and post procedures (p<0,001). Conclusions The use of an ultra-low-dose CM pulmonary arterial injection protocol for CTA in TAVI candidates does not affect the renal function and procedural success rate is high and the clinical outcomes after TAVI is satisfactory according to the litterature.