Objectives: The purpose of this study was to prospectively investigate the diagnostic and prognostic impact of cardiac magnetic resonance (CMR) T1 mapping and validate it against left ventricular biopsies.
Background: Extracellular volume (ECV) expansion is a key feature of heart failure. CMR T1 mapping has been developed as a noninvasive technique to estimate ECV; however, the diagnostic and prognostic impacts of this technique have not been well established.
Methods: A total of 473 consecutive patients referred for CMR (49.5% female, age 57.8 ± 17.1 years) without hypertrophic cardiomyopathy, cardiac amyloidosis, or Anderson-Fabry disease were studied. T1 mapping with the modified Look-Locker inversion recovery (MOLLI) sequence was used for ECV calculation (CMR-ECV). For methodological validation, 36 patients also underwent left ventricular biopsy, and ECV was quantified by TissueFAXS analysis (TissueFAXS-ECV). To assess the prognostic value of CMR-ECV, its association with hospitalization for cardiovascular reasons or cardiac death was tested in a multivariable Cox regression model.
Results: TissueFAXS-ECV was 26.3 ± 7.2% and was significantly correlated with CMR-ECV (r = 0.493, p = 0.002). Patients were followed up for 13.3 ± 9.0 months and divided into CMR-ECV tertiles for Kaplan-Meier analysis (tertiles were ≤ 25.7%, 25.8% to 28.5%, and ≥ 28.6%). Significantly higher event rates were observed in patients with higher CMR-ECV (log-rank p = 0.013). By multivariable Cox regression analysis, CMR-ECV was independently associated with outcome among imaging variables (p = 0.004) but not after adjustment for clinical parameters.
Conclusions: CMR T1 mapping allows accurate noninvasive quantification of ECV and is independently associated with event-free survival among imaging parameters. Its prognostic value on top of established clinical risk factors warrants further investigation in long-term studies.
Keywords: T1 mapping; cardiac magnetic resonance imaging; extracellular matrix; outcome.
Copyright © 2016 American College of Cardiology Foundation. Published by Elsevier Inc. All rights reserved.