Three-dimensional transoesophageal echocardiography is crucial for valid assessment of mitral valve leaflet morphology in severe mitral regurgitation prior to interventional repair

BACKGROUND: Interventional mitral valve (MV) repair of severe symptomatic mitral regurgitation (MR) is a therapeutic option in high-risk surgical or inoperable patients. Assessment of the MV remains a crucial part of pre-interventional screening. Three-dimensional transoesophageal echocardiography (3D-TOE) may compensate for well-known pitfalls that occur in 2D-TOE. PURPOSE: We investigated whether the functional length of the central segments of the posterior and anterior MV leaflets (PML-P2 and AML-A2) is more reliably determined by 3D-TOE full volume datasets (3D-MPR) or orthogonal biplane-imaging (Xplane) when compared to 2D-TOE. METHODS AND RESULTS: Between February 2014 and August 2015, 265 consecutive patients with moderate to severe symptomatic MR were screened. Seventy patients were judged suitable for interventional MV repair by the in-house Heart-Team. Eventually, 59 patients remained for data analysis. Inter-observer variability was lowest in 3D-MPR followed by Xplane (r = 0.92 and 0.90, p < .001 for both) and highest in Mplane (r = 0.82, p < .001). Mean functional PML-P2 lengths were similar in Xplane (12.6 ± 1.7 mm) and 3D-MPR (12.1 ± 2.0 mm), however, significantly different in 2D-TOE (10.0 ± 2.1 mm, p < .001). 2D-TOE underestimated PML-P2 length with a bias of -2.5 mm compared to Xplane and -1.95 mm compared to 3D-MPR. In contrast, functional AML-A2 length was determined similar across all methods. CONCLUSIONS: Our results demonstrate the superiority of 3D-TOE over 2D-TOE for accurate MV assessment in MR, especially for the determination of the functional PML length. Erroneous MV leaflet assessment may result in inadequate therapy restriction if the MV is deemed not suitable for interventional repair.