Quantification of left ventricular fibrosis in arrhythmic mitral valve prolapse patients: comparison of different semi-automated techniques assessed by cardiac magnetic resonance

Abstract

Abstract Background Left ventricular (LV) fibrosis has a key role in arrhythmogenesis in mitral valve prolapse (MVP) patients. Cardiac magnetic resonance (CMR) demonstrated able to clearly identify LV fibrosis with the post-contrast late gadolinium enhancement (LGE) images. Despite the pivotal role of LV fibrosis in the arrhythmogenesis, a quantification and identification of reproducible method able to accurately measure LGE in arrhythmic MVP patients has not been recognized. Purpose We aimed to measure and compare different semi-quantitative methods for LGE quantification assessed by CMR, in order to identify the most reproducible one, in arrhythmic MVP patients. Methods 66 arrhythmic MVP patients with normal systolic function and without significant regurgitation were enrolled. Semi-automated gray-scale thresholding technique using full with at half maximum (FWHM) and 2, 3 and 5 standard deviation (SD) above the remote myocardium were used and compared with visual assessment (Fig. 1). Results LGE was identified in 41 arrhythmic MVP patients (62%) and quantified (Fig. 2). 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 quantification visually assessed (2.402±1.075 vs 2.363±0.9909, p: 0.543). Despite all semi-quantitative methods for LGE quantification demonstrated a good intra and inter-observer agreement, the 5-SD threshold quantification, both in percentage and in grams, revealed the less intra-observer (respectively, ICC: 0.976 and 0.966) and inter-observer variability (respectively ICC: 0.948 and 0.935) when compared with visual assessment. Conclusion This is the first study that quantified and compared different CMR semi-automated methods for LGE assessment in a population of arrhythmic MVP patients. The 5-SD gray-scale threshold technique in percentage revealed the best correlation with the visual assessment and an optimal reproducibility. Funding Acknowledgement Type of funding sources: None.