Relation of Strain by Feature Tracking and Clinical Outcome in Children, Adolescents, and Young Adults With Hypertrophic Cardiomyopathy

• In young patients with hypertrophic cardiomyopathy, strain by feature tracking is reduced in hypertrophied segments.
• Global radial and longitudinal strains are decreased in patients with hypertrophic cardiomyopathy with adverse events.
• Intraobserver and interobserver variabilities are high, necessitating refinement before clinical use.

Evaluation of hypertrophic cardiomyopathy (HC) in young patients is limited by lack of age-specific norms for wall thickness on cardiovascular magnetic resonance (CMR) images. Left ventricular strain may have a role in identifying and risk stratifying patients with HC, but few data exist for strain measurement on CMR images. In 30 patients (14.1 ± 3.2 years) with clinically diagnosed HC and 24 controls (15.6 ± 2.8 years), strain (radial, longitudinal, and circumferential) was evaluated by 2 experienced readers using CMR feature tracking. In patients with HC, hypertrophied segments had decreased radial (28.0 ± 5.2% vs 58.6 ± 3.9%, p = 0.0002), circumferential (−23.7 ± 1.1% vs −28.3 ± 0.8%, p = 0.004), and longitudinal (−11.2 ± 1.2% vs −21.7 ± 0.8%, p <0.0001) strains versus control segments. Hypertrophied segments had decreased longitudinal (basal segments −12.2 ± 1.9% vs −22.6 ± 1.2%, p = 0.0002), radial (basal segments 22.7 ± 10.8% vs 78.8 ± 7.2%, p = 0.0001), and circumferential (basal segments −22.4 ± 1.7% vs −30.6 ± 1%, p = 0.0004) strains versus nonhypertrophied segments in patients with HC. Longitudinal strain had the lowest intraobserver and interobserver variabilities (coefficient of variability −15.7% and −18.5%). After a median follow-up of 28.1 months (interquartile range [IQR] 4.2 to 33.1), 7 patients with HC with an adverse event outcome (5 ventricular tachycardia, 1 appropriate implantable cardioverter-defibrillator discharge, and 1 death) had reduced global radial (median 39.7%, IQR 39.6% to 46.6% vs 65.4%, IQR 46.1% to 83.4%, p = 0.01) and longitudinal strains (median −16.5%, IQR −18.7% to −15.5% vs −19.7%, IQR −23.8% to −17.5%, p = 0.046) compared with patients with HC without an event. In conclusion, CMR feature tracking detects differences in global and segmental strains and may represent a novel method to predict clinical outcome in patients with HC. Further study is necessary to evaluate longitudinal changes in this population.