Myocardial fibrosis by T1 mapping magnetic resonance imaging predicts incident cardiovascular events and all-cause mortality: The Multi-Ethnic Study of Atherosclerosis

Aims To evaluate whether myocardial fibrosis predicts cardiovascular events (CVEs) and mortality in the Multi-Ethnic Study of Atherosclerosis.Methods Cardiac magnetic resonance (CMR) T1 mapping with gadolinium administration for assessment of extracellular vol- and results ume fraction (ECV) was performed in 1326 participants, in whom myocardial scar was assessed by late gadolinium enhancement (LGE). The clinical outcomes were defined as all-cause mortality, atherosclerotic CVEs, and incident heart failure (HF) during an average of 8 years of follow-up after the scan. Participants’ mean native T1 time was 971 ms [standard deviation (SD) 45.5], ECV was 27 (SD 2.9), and 117 (8.8%) of them had LGE. At the time of the CMR exam, participant age was 68 years (SD 9) and 48% of them were women. Ideal cut-offs were identified using classification and regression trees accounting for time-to-event outcomes for ECV (30%) and native T1 time (954 ms). Over the follow-up period, 106 participants died, 78 developed CVE, and 23 developed HF. After adjustment for risk factors, ECV >30% was associated with death [hazard ratio (HR): 1.67, P < 0.05], incident CVE (HR: 2.02, P < 0.05), and incident HF (HR: 2.85, P < 0.05). After adjustments, native T1 >954 ms was associated with incident CVE (HR: 2.09, P < 0.05). Myocardial scar by LGE was not predictive of clinical outcomes after adjustments. Conclusion ECV is an independent prognostic marker of incident HF, atherosclerotic CVEs, and all-cause mortality. ECV, with its ability to characterize both diffuse and focal fibrosis processes, better predicted incident events than regional myocardial abnormalities as visualized by LGE imaging in a large multi-ethnic population.