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

Abstract

To evaluate whether myocardial fibrosis predicts cardiovascular events (CVEs) and mortality in the Multi-Ethnic Study of Atherosclerosis. Cardiac magnetic resonance (CMR) T1 mapping with gadolinium administration for assessment of extracellular volume 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. 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.