Assessment of left ventricular function measured with cardiac MRI feature tracking predicts heart failure events in childhood hypertrophic cardiomyopathy

Background Hypertrophic cardiomyopathy (HCM) is the most common heritable myocardial disease, but far less frequent in pediatric populations. Compared to adult HCM, pediatric patients have a higher risk of developing left ventricular dysfunction and may be more likely and early to experience cardiovascular events. Strain with CMR Feature Tracking (CMR-FT) analysis allows sensitive evaluation of tissue deformation than LVEF and thus may have a role in identifying patients at risk of Heart faliure(HF). However, the prognostic value of strain has not been specifically studied in a pediatric cohort with HCM. Thus, we sought to investigate the association between LV strain parameters derived from CMR feature-tracking and HF-related events, and evaluate the possible incremental prognostic benefit beyond clinical features and traditional CMR features. Methods This retrospective study consecutively involved 228 primary HCM patients aged ≤18 years with contrast-enhanced CMR. The extent of LGE was quantified by measuring areas with the increased signal intensity of ≥ 6 standard deviations above the mean of normal myocardium. The CMR-FT analysis was performed on the acquired cine images in short-axis and three long axis views (2-chamber, 4-chamber, and LV outflow tract) with global longitudinal strain (GLS), global radial strain (GRS) and global circumferential strain (GCS). HF-related events include HF-related mortality, unscheduled hospitalizations for HF management, and heart transplantation. Results Patients were 15±3 years of age at baseline and 65% were male. During a median follow-up of 61.4 months (IQR: 39.0-84.3), 13(6.5%) patients with HCM reached HF-related events. Including heart transplantation in 2, HF-related death in 4, unscheduled hospitalizations for HF in 7. Patients suffering from HF-related events had larger LV diameter, higher LV mass index and LGE extent, worser GLS, GRS and lower early GLS rate than patients without HF-related events. According to Kaplan-Meier analysis, patients with worse GLS were more likely to experience HF-related events (log-rank P < 0.001). Similar results were observed in worser GRS group (log-rank P = 0.002), worser GCS group (log-rank P = 0.009) and lower early GLS rate (log-rank P < 0.001) group. After univariable analysis and multivariable Cox analysis adjusting clinical and cardiac functional factors respectively, GLS (HR: 1.32, 95%CI: 1.05-1.67, P = 0.020) and LGE extent (HR: 1.13, 95%CI: 1.03-1.23, P = 0.006) were still an independent predictor for HF-related events. Besides, the addition of GLS significantly improved the model’s performance in comparison with the model of traditional markers of LVEF and LGE presence (C index: 0.73 vs 0.88, Delong’s P < 0.001) Conclusion Myocardial strain using CMR-FT provides independent and incremental prognostic value over clinical features, LVEF, and LGE in childhood HCM. CMR-FT may serve as a novel marker to improve risk stratification in childhood HCM.overview K-M analysis of HF related events