Feasibility of Cardiovascular Magnetic Resonance to Assess the Orifice Area of Aortic Bioprostheses

Abstract

Background— Prosthetic orifice area, usually calculated by transthoracic echocardiography (TTE) or transesophageal echocardiography (TEE), provides important information regarding the hemodynamic performance of aortic bioprostheses. However, both TTE and TEE have limitations; therefore accurate and reproducible determination of the orifice area often remains a challenge. The present study aimed to investigate the feasibility of cardiovascular magnetic resonance (CMR) to assess the orifice areas of aortic bioprostheses. Methods and Results— CMR planimetry of the orifice area was performed in 65 patients (43/22 stented/stentless prostheses; mean time since implantation, 3.1�2.8 years; mean orifice area [TTE], 1.70�0.43 cm 2 ; 62 normally functioning prostheses, 2 severe stenoses, and 1 severe regurgitation) in an imaging plane perpendicular to the transprosthetic flow using steady-state free-precession cine imaging under breath-hold conditions on a 1.5-T MR system. CMR results were compared with TTE (continuity equation, n=65) and TEE (planimetry, n=31). CMR planimetry was readily feasible in 80.0%; feasible with limitation in 15.4% because of stent, flow, and sternal wire artifacts; and impossible in 4.6% because of flow artifacts. Correlations of the orifice areas by CMR with TTE ( r =0.82) and CMR with TEE ( r =0.92) were significant. The average difference between the methods was −0.02�0.24 cm 2 (TTE) and 0.05�0.15 cm 2 (TEE). Agreement was present for stented and stentless devices and independent of orifice size. Intraobserver and interobserver variabilities of CMR planimetry were 6.7�5.4% and 11.5�7.8%. Conclusions— The assessment of aortic bioprostheses with normal orifice areas by CMR is technically feasible and provides orifice areas with a close correlation to echocardiography and low observer dependency.