Abstract 5808: Assessment of Aortic Bioprostheses is Feasible Applying Cardiovascular Magnetic Resonance - In Vivo and In Vitro Studies
Orifice area is decisive to assess bioprosthetic performance after aortic valve replacement. However, standard calculation by transthoracic echocardiography (TTE) is often limited. This is the first series testing cardiovascular magnetic resonance (CMR) to quantify the orifice area of bioprostheses. Prosthetic orifice visualization was performed in a clinical 1.5T MR system (Siemens Magnetom Avanto) within a stack of prosthesis parallel steady state free precession cines (slice thickness 5mm, no gap). Orifice quantification was done manually by planimetry. In vivo, we compared the orifice area obtained by CMR with TTE (continuity equation) prospectively in 56 patients with aortic bioprostheses (40 stented, 16 stentless). In a subgroup of 23 patients also transesophageal echocardiography (planimetry; TEE) was applied. In vitro, we studied four different bioprostheses in a CMR-compatible pulsatile flow model under standardized conditions. In vivo, CMR planimetry was feasible in 52 patients (92.9%). Atrial fibrillation with rapid heart rate, inability to sustain breath holds and flow-artifacts rendered image-quality non-diagnostic in 3 patients. Three patients had insufficient transthoracic acoustic windows. Correlations of CMR with TTE (n=50; r=0.85; p<0.001) and CMR with TEE (n=21; r=0.97; p<0.001) were highly significant, both for stentless and stented bioprostheses. In Bland-Altman analysis, mean difference between CMR and TTE was −0.06±0.24cm2, between CMR and TEE 0.03±0.12cm2. In vitro, mean orifice areas obtained by CMR planimetry were 1.60±0.04cm2 for Hancock 25, 1.59±0.01cm2 for Perimount 23, 1.29±0.07cm2 for Perimount 21 and 1.56±0.04cm2 for Mitroflow 25. The assessment of bioprostheses by CMR is technically feasible and provides orifice areas with close correlation to echocardiography. Thus, CMR is an important non-invasive tool to assess bioprostheses in selected patients. The flow model allows for establishing CMR specific reference orifice areas for various valve types and comparing their hydrodynamic performance under standardized conditions. The concepts and information presented in this abstract are based on research and are not commercially available.