Changes in CMR-derived ventricular strain, fibrosis progression and outcomes in hypertrophic cardiomyopathy

: Hypertrophic cardiomyopathy (HCM) is a major health concern, with cardiac magnetic resonance (CMR) playing a crucial role in risk assessment. We investigated for the first time the utility of sequential CMR, particularly strain analysis, for tracking HCM progression. We retrospectively evaluated HCM patients undergoing two CMR scans over a 10-year period. We measured changes in left ventricular (LV) strain parameters and examined their yearly changes as predictors of a composite of sudden cardiac death, life-threatening ventricular arrhythmias, stroke, new-onset atrial fibrillation, and heart failure hospitalizations. Patients (n = 114) were predominantly male (73%), with a median age of 51 years (interquartile range 36-60), obstructive HCM in 14%, and a median HCM risk score of 2% (1-3%). Only one patient (0.9%) had LGE ≥ 15% on the first scan, while 8 (7.0%) had LGE ≥ 15% after a median of 5.1 years (3.5-6.5). Absolute changes in LV strain displayed significant relationships with changes in LGE mass (longitudinal strain: beta = 0.227, p = 0.016; circumferential strain: beta = 0.421, p < 0.001; radial long-axis: beta=-0.261, p = 0.006). During a 4.3-year median follow-up after the second CMR scan (interquartile range 2.2-6.9), 40 patients experienced an event; hard arrhythmic events were infrequent. Among patients with LGE < 15% at baseline, yearly absolute changes in radial short-axis strain predicted outcomes beyond baseline HCM score and LGE extent (hazard ratio 1.12, 95% confidence interval 1.03-1.22, p = 0.011). In patients with predominantly early-stage HCM, worsening short-axis radial strain was associated with composite adverse events after the second CMR, independent of baseline LGE and ESC SCD risk.