Routine cine-CMR for prosthesis-associated mitral regurgitation: a multicenter comparison to echocardiography

BACKGROUND AND AIM OF THE STUDY: Mitral regurgitation (MR) is an important complication after prosthetic mitral valve (PMV) implantation. Transthoracic echocardiography is widely used to screen for native MR, but can be limited with PMV. Cine-cardiac magnetic resonance (CMR) holds the potential for the non-invasive assessment of regurgitant severity based on MR-induced inter-voxel dephasing. The study aim was to evaluate routine cine-CMR for the visual assessment of PMV-associated MR.

METHODS: Routine cine-CMR was performed at nine sites. A uniform protocol was used to grade MR based on jet size in relation to the left atrium (mild < 1/3, moderate 1/3-2/3, severe > 2/3). MR was graded in each long-axis orientation, with overall severity based on cumulative grade. Cine-CMR was also scored for MR density and pulmonary vein systolic flow reversal (PVSFR). Visual interpretation was compared to quantitative analysis in a single-center (derivation) cohort, and to transesophageal echocardiography (TEE) in a multicenter (validation) cohort.

RESULTS: The population comprised 85 PMV patients (59% mechanical valves, 41% bioprostheses). Among the derivation cohort (n = 25), quantitative indices paralleled visual scores, with stepwise increases in jet size and density in relation to visually graded MR severity (both p = 0.001). Patients with severe MR had an almost three-fold increase in quantitative jet area (p = 0.002), and a two-fold increase in density (p = 0.04) than did other patients. Among the multicenter cohort, cine-CMR and TEE (Δ =. 2 ± 3 days) demonstrated moderate agreement (κ = 0.44); 64% of discordances differed by ≤ 1 grade (Δ = 1.2 ± 0.5). Using a TEE reference, cine-CMR yielded excellent diagnostic performance for severe MR (sensitivity, negative predictive value = 100%). Patients with visually graded severe MR also had more frequent PVSFR (p < 0.001), denser jets (p < 0.001), and larger left atria (p = 0.01) on cine-CMR.

CONCLUSION: Cine-CMR is useful for the assessment of PMV-associated MR, which manifests concordant quantitative and qualitative changes in size and density of inter-voxel dephasing. Visual MR assessment based on jet size provides an accurate non-invasive means of screening for TEE-evidenced severe MR.