Left ventricular fibrosis in arrhythmic mitral valve prolapse: quantification and comparison of semi-automated techniques assessed by cardiac magnetic resonance

Purpose Left ventricular (LV) fbrosis has a key role in arrhythmogenesis in patients with mitral valve prolapse (MVP). Cardiac magnetic resonance identifes LV fbrosis by using late gadolinium enhancement (LGE) technique. LGE assessment and quantifcation in patients with MVP lacks of standardization protocols. Methods 66 MVP patients with normal systolic function and without signifcant regurgitation were enrolled. Semi-automated gray-scale thresholding techniques using full width at half maximum (FWHM) and 2, 3 and 5 standard deviation (SD) above the remote myocardium were used and compared with the visual assessment, considered as the gold standard. Results LGE was identifed in 41 MVP patients (62%) and quantifed. The mean quantity of LGE visually assessed was 2.40±1.07% or 1.40±0.82 g. With FWHM, LGE resulted 3.56±1.23% or 1.99±1.13 g. Using thresholding, the mean LGE quantity was 9.2±3.1% or 4.82±2.28 g for 2-SD, 5.72±1.75% or 3.06±1.47 g for 3-SD and 2.36±0.99% or 1.29±0.79 g for 5-SD. The 5-SD measurement in percentage demonstrated a good correlation with LGE quantifcation visually assessed (2.40±1.07 vs. 2.363±0.9909, p = 0.543). When compared with the gold standard, the 5-SD threshold quantifcation, both in percentage and in grams, revealed the least intra-observer (respectively, ICC: 0.976 and 0.966) and inter-observer variability (respectively ICC: 0.948 and 0.935). Conclusion The 5-SD gray-scale threshold technique in percentage revealed the best correlation with the visual assessment and an optimal reproducibility in MVP patient.