The prognostic and incremental value of T1 mapping for predicting adverse events in hypertrophic cardiomyopathy

Abstract Background In patients with hypertrophic cardiomyopathy (HCM), the prognostic value of native T1 and extracellular volume fraction (ECV) for adverse cardiovascular events has not been well defined. Methods Consecutive 663 participants with HCM who underwent cardiovascular magnetic resonance (CMR) were recruited. The follow-up endpoints included heart failure (HF)-related death and sudden cardiac death (SCD) or aborted SCD. Results During the median follow-up time of 44 months (interquartile range [IQR]: 23 to 66.0 months), 56 (8.4%) participants reached composite endpoints including 38 (5.7%) with SCD or aborted SCD, 16 (2.4%) with HF-related death and 2 (0.3%) with heart transplantation. On multivariable Cox proportional hazards regression analyses, native T1 including late gadolinium enhancement (LGE) from three short axes were significantly associated with cardiac death (basal native T1: hazard ratio [HR], 1.06 per 10 ms increase; 95% confidence interval [CI], 1.02 to 1.09; middle native T1: HR, 1.05 per 10 ms increase; 95% CI, 1.01 to 1.09; apical native T1: HR, 1.04 per 10 ms increase; 95% CI, 1.02 to 1.07; all P < 0.05) after adjustment for non-sustained ventricular tachycardia, history of syncope, the extent of LGE, left atrial size, and NYHA class. Conversely, only basal ECV was associated with cardiac death (basal ECV including LGE area: HR, 1.08 per 1% increase, 95%CI, 1.03 to 1.13, P = 0.001; basal ECV excluding LGE: HR, 1.1 per 1% increase; 95%CI, 1.04 to 1.16; P < 0.001) In addition, participants with increased mean native T1 (≥1349.4 ms) or basal ECV(≥ 29.4%) were more likely to suffer from cardiac death in the entire study cohort or the subgroup with low LGE extent (<15%) or low ESC risk score (<6%) (all P < 0.05). Furthermore, the addition of mean LV native T1 (≥1349.4 ms) or basal ECV (≥ 29.4%) to current risk factors in the guidelines could further improve prediction for the composite endpoint (C-index increased to 0.719 from 0.521 for the AHA/ACC risk model, P < 0.001; C index increased to 0.709 from 0.514 for the ESC risk model; P < 0.001). Conclusions In this study of patients with HCM, mean native T1 of three short axes and basal ECV were independently associated with cardiac death and added incremental value to conventional clinical predictors for patients with HCM.Figure 1.Demonstrative images.Figure 2 Incremental Value of T1 mapping