Incremental significance of myocardial oedema for prognosis in hypertrophic cardiomyopathy

To explore the prognosis of myocardial oedema measured by T2 mapping in hypertrophic cardiomyopathy (HCM).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.Patients with HCM with LGE(+) and higher T2 had worse prognosis than those with LGE(+) and lower T2.