Feature-tracking cardiac magnetic resonance method: a valuable marker of replacement fibrosis in hypertrophic cardiomyopathy

Purpose
Left ventricular (LV) replacement fibrosis is a marker of adverse cardiac events in hypertrophic cardiomyopathy (HCM). We aimed to assess the efficacy of the feature-tracking cardiac magnetic resonance (FT-CMR) in the detection of LV replacement fibrosis.

Material and methods
Fifty-one patients with HCM (51% female, mean age = 21 ± 5.2 years) and significant myocardial hypertrophy, who underwent CMR between February 2018 and December 2019 were enrolled. Functional and 3D FT-CMR parameters were measured. LV global longitudinal strain, global radial strain (GRS), and global circumferential strain (GCS) were recorded. The percentage of enhanced myocardial mass was calculated. Univariate and multivariate regression analyses were performed to determine the predictors of fibrosis. A p-value of less than 0.05 was considered significant.

Results
The mean enhanced mass percentage was 15.2 ± 10.53%. Among LV volumetric parameters, end-systolic and end-diastolic volume indices predicted fibrosis (fitness [F] = 8.11 and p = 0.006 vs. F = 6.6 and p = 0.012, correspondingly). The univariate linear regression demonstrated that GCS and GRS predicted total enhanced mass (%) (F = 12.29 and p = 0.001 vs. F = 7.92 and p = 0.007, respectively). After the inclusion of all volumetric and deformation parameters, the multivariate analysis identified the model of a combination of LV end-diastolic volume index (LV EDVI) and LV GCS as a robust predictor of the fibrosis percentage (F = 8.86 and p = 0.005).

Conclusions
Non-contrast CMR parameters including LV GCS and LV EDVI are valuable markers of replacement fibrosis in HCM patients with notable myocardial hypertrophy.