Assessment of mitral bioprostheses using cardiovascular magnetic resonance.
BACKGROUND
The orifice area of mitral bioprostheses provides important information regarding their hemodynamic performance. It is usually calculated by transthoracic echocardiography (TTE), however, accurate and reproducible determination may be challenging. Cardiovascular magnetic resonance (CMR) has been proven as an accurate alternative for assessing aortic bioprostheses. However, whether CMR can be similarly applied for bioprostheses in the mitral position, particularly in the presence of frequently coincident arrhythmias, is unclear. The aim of the study is to test the feasibility of CMR to evaluate the orifice area of mitral bioprostheses.


METHODS
CMR planimetry was performed in 18 consecutive patients with mitral bioprostheses (n = 13 Hancock(R), n = 4 Labcore(R), n = 1 Perimount(R); mean time since implantation 4.5 +/- 3.9 years) in an imaging plane perpendicular to the transprosthetic flow using steady-state free-precession cine imaging under breath-hold conditions on a 1.5T MR system. CMR results were compared with pressure half-time derived orifice areas obtained by TTE.


RESULTS
Six subjects were in sinus rhythm, 11 in atrial fibrillation, and 1 exhibited frequent ventricular extrasystoles. CMR image quality was rated as good in 10, moderate in 6, and significantly impaired in 2 subjects. In one prosthetic type (Perimount(R)), strong stent artifacts occurred. Orifice areas by CMR (mean 2.1 +/- 0.3 cm2) and TTE (mean 2.1 +/- 0.3 cm2) correlated significantly (r = 0.94; p < 0.001). Bland-Altman analysis showed a 95% confidence interval from -0.16 to 0.28 cm2 (mean difference 0.06 +/- 0.11 cm2; range -0.1 to 0.3 cm2). Intra- and inter-observer variabilities of CMR planimetry were 4.5 +/- 2.9% and 7.9 +/- 5.2%.


CONCLUSIONS
The assessment of mitral bioprostheses using CMR is feasible even in those with arrhythmias, providing orifice areas with close agreement to echocardiography and low observer dependency. Larger samples with a greater variety of prosthetic types and more cases of prosthetic dysfunction are required to confirm these preliminary results.
von Knobelsdorff-Brenkenhoff
Florian
F
Working Group on Cardiovascular Magnetic Resonance, Medical University Berlin, Charité Campus Buch, HELIOS Klinikum Berlin-Buch, Department of Cardiology and Nephrology, Schwanebecker Chaussee 50, 13125 Berlin, Germany. florian.von-knobelsdorff@charite.de
Rudolph
André
A
Wassmuth
Ralf
R
Schulz-Menger
Jeanette
J
D001705:Bioprosthesis; D004452:Echocardiography; D005240:Feasibility Studies; D005260:Female; D006350:Heart Valve Prosthesis; D006801:Humans; D008279:Magnetic Resonance Imaging; D008297:Male; D008943:Mitral Valve / Q000000981:diagnostic imaging* / Q000473:pathology*; D015588:Observer Variation