Incremental significance of myocardial oedema for prognosis in hypertrophic cardiomyopathy

AIMS: To explore the prognosis of myocardial oedema measured by T2 mapping in hypertrophic cardiomyopathy (HCM). METHODS AND RESULTS: A total of 674 patients with HCM (age: 50 ± 15 years, 60.5% males) who underwent cardiovascular magnetic resonance were prospectively enrolled from 2011 to 2020. One hundred healthy controls (age: 48 ± 19 years, 58.0% males) were included for comparison. Myocardial oedema was quantitatively measured by T2 mapping in both global and segmental myocardium. The endpoints were defined as a combination of cardiovascular death and appropriate implantable cardioverter defibrillator discharge. During a median follow-up of 36 months (interquartile range: 24-60 months), 55 patients (8.2%) had cardiovascular events. Patients with cardiovascular events had a higher T2 max, T2 min, and T2 global values (all P < 0.001) than patients who remained event free. Survival analysis demonstrated that patients with HCM with late gadolinium enhancement [LGE(+)] and T2 max ≥44.9 ms had a higher risk of developing cardiovascular events (P < 0.001). A multivariate Cox regression analysis showed that T2 max, T2 min, and T2 global provided significant prognostic value to predict cardiovascular events (all P < 0.001). According to the C-index (0.825, 0.814), net reclassification index (0.612, 0.536, both P < 0.001), and integrative discrimination index (0.029, 0.029, both P < 0.05), T2 max or T2 min significantly increased the predictive performance of established risk factors, including extensive LGE. CONCLUSION: Patients with HCM with LGE(+) and higher T2 had worse prognosis than those with LGE(+) and lower T2.