Age-dependent hypertrophy and fibrosis dynamics in hypertrophic cardiomyopathy: Insights from longitudinal CMR studies.

BACKGROUND

This study aims to evaluate the progression of morphological and functional alterations over time in patients with hypertrophic cardiomyopathy (HCM) using Cardiac Magnetic Resonance (CMR).

METHODS

A retrospective analysis was conducted on patients with HCM who underwent serial CMR at 1.5 Tesla. Left ventricular (LV) mass was measured during diastole, including papillary muscles and trabeculae assessment. Appearance of Late Gadolinium Enhancement (LGE) was volumetrically quantified using a 5-standard-deviation (SD) threshold.

RESULTS

Thirty-two patients, with a mean age of 44 ± 16 years (range: 11-70 years), were evaluated after an average follow-up period of 5.2 ± 2.4 years (range: 0.8-9.1 years). Significant increases were observed in LV mass (from 194 ± 56 g to 217 ± 60 g; p = 0.0001), septal wall thickness (from 18 ± 4 mm to 19 ± 4 mm; p = 0.01), LGE mass (from 6 ± 17 g to 8 ± 18 g; p = 0.006), and left atrial volume (from 109 ± 41 ml to 129 ± 40 ml; p = 0.0001). Both left and right ventricular ejection fractions (LVEF and RVEF) significantly decreased over time (LVEF: from 70 ± 9 % to 66 ± 9 %; p = 0.04 and RVEF: from 70 ± 7 % to 67 ± 9 %; p = 0.02). Multivariate regression analysis revealed that HCM mass gain was independently associated with age (B = -0.43; p = 0.02) and LGE mass (B = -0.46; p = 0.02). The median LV mass gain rate in adults was 1.7 g per year/BSA (IQR, 0.6-2.7) compared to 6.0 g per year/BSA (IQR, 0.5-11.6) in adolescents (mean age: 16 years; range: 11-20 years). A positive correlation was found between LV mass and LGE mass (B = 0.55; p = 0.001), while an inverse relationship was observed between LV mass gain and LGE mass gain rates (-0.37; p = 0.03).

CONCLUSION

The range of morphological changes in HCM seems to reflect an age-related equilibrium between hypertrophy and fibrosis. The extent of changes in LV mass, fibrosis, and functional decline in HCM may help identify patients at risk, emphasizing the importance of ongoing follow-up studies.