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- Open Access
Pathophysiology of myocardial remodeling in survivors of ST-elevation myocardial infarction revealed by native T1 mapping: inflammation, remote myocardium and prognostic significance
© Carrick et al; licensee BioMed Central Ltd. 2015
- Published: 3 February 2015
- Cardiac Magnetic Resonance
- Major Adverse Cardiac Event
- STEMI Patient
- Monocyte Count
- Remote Myocardium
The pathophysiology and prognostic significance of remote myocardium in the natural history of STEMI is uncertain. Cardiac magnetic resonance (CMR) provides a non-invasive assessment of myocardial pathology that is spatially and temporally coordinated. Native T1 quantified by CMR (T1 relaxation time, milliseconds) is a fundamental tissue property determined by water content and cellularity. We aimed to investigate the clinical significance of remote myocardium in survivors of acute ST-elevation myocardial infarction (STEMI) using native T1 mapping.
We performed a prospective single center cohort study in reperfused STEMI patients who underwent CMR 2 days and 6 months post-MI and long term follow-up (18 months minimum). Native T1 CMR (MOLLI investigational prototype sequence: 3 (3) 3 (3) 5) was measured in regions-of-interest in remote and injured myocardium. Infarction was depicted on late gadolinium contrast enhancement imaging. Adverse remodeling was defined as an increase in left ventricular end-diastolic volume ≥ 20% at 6 months. Major adverse cardiac events (MACE) were defined as cardiac death or hospitalization for non-fatal MI or heart failure. Results are mean±SD unless specified.
300 STEMI patients (mean age 59 years, 74% male) gave informed consent (14 July 2011 - 21 November 2012). Of these, 288 STEMI patients had evaluable native T1 CMR and follow-up data (median duration 845 days). Infarct size was 18±14% of left ventricular mass. Two days post-STEMI, native T1 in remote myocardium was lower than native T1 in the infarct zone (961±25 ms vs. 1097±52 ms; p<0.01). In multivariable linear regression, remote zone native T1 was independently associated with incomplete ST-segment resolution (9.42 (2.37 to 16.47); p=0.009), the log of the initial CRP concentration (regression coefficient 3.01 (95% CI 0.016 to 5.55); p=0.038) and the peak monocyte count within 2 days of admission (10.20 (0.74, 19.67); p=0.035).
At 6 months, left ventricular end-diastolic volume increased by 5 (25) ml (n=262 patients with evaluable data) overall, and adverse remodeling occurred in 30 (12%) patients. Remote zone native T1 was a multivariable predictor of the change in left ventricular end-diastolic volume from baseline (0.13 (0.01, 0.24); p=0.035).
39 (13.5%) patients experienced a MACE including 20 (6.9%) patients with a post-discharge MACE. Remote zone native T1 was an independent predictor of post-discharge MACE (hazard ratio 1.016, 95% CI 1.000, 1.032; p=0.048) including after adjustment for changes in LVEF (p=0.032), LV end-diastolic volume (p=0.053), and monocyte count (p=0.036).
Remote zone tissue characteristics early post-MI are temporally linked with reperfusion injury and inflammation and independently predict left ventricular remodeling and MACE in STEMI survivors.
This article is published under license to BioMed Central Ltd. This is an Open Access article distributed under the terms of the Creative Commons Attribution License (http://creativecommons.org/licenses/by/4.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited. The Creative Commons Public Domain Dedication waiver (http://creativecommons.org/publicdomain/zero/1.0/) applies to the data made available in this article, unless otherwise stated.