Abstract
BackgroundCardiovascular magnetic resonance permits assessment of irreversible myocardial fibrosis and contractile function in patients with previous myocardial infarction. We aimed to assess the prognostic value of myocardial fibrotic tissue with preserved/restored contractile activity.MethodsIn 730 consecutive myocardial infarction patients (64 ± 11 years), we quantified left ventricular (LV) end-diastolic (EDV) and end-systolic (ESV) volumes, ejection fraction (EF), regional wall motion (WM) (1 normal, 2 hypokinetic, 3 akinetic, 4 dyskinetic), and WM score index (WMSI), and measured the transmural (1–50 and 51–100) and global extent of the infarct scar by late gadolinium enhancement (LGE). Contractile fibrotic (CT-F) segments were identified as those showing WM-1 and WM-2 with LGE ≤ or ≥ 50%.ResultsDuring follow-up (median 2.5, range 1–4.7 years), cardiac events (cardiac death or appropriate implantable defibrillator shocks) occurred in 123 patients (17%). At univariate analysis, age, LVEDV, LVESV, LVEF, WMSI, extent of LGE, segments with transmural extent > 50%, and CT-F segments were associated with cardiac events. At multivariate analysis, age > 65 years, LVEF < 30%, WMSI > 1.7, and dilated LVEDV independently predicted cardiac events, while CT-F tissue was the only independent predictor of better outcome. After adjustment for LVEF < 30% and LVEDV dilatation, the presence of CT-F tissue was associated with good prognosis.ConclusionsIn addition to CMR imaging parameters associated with adverse outcome (severe LV dysfunction, poor WM, and dilated EDV), the presence of fibrotic myocardium showing contractile activity in patients with previous myocardial infarction yields a beneficial effect on patient survival.
Highlights
Cardiovascular magnetic resonance permits assessment of irreversible myocardial fibrosis and contractile function in patients with previous myocardial infarction
Left ventricular (LV) dysfunction is a common finding after myocardial infarction (MI) that is associated with high morbidity and mortality in patients with heart failure [1, 2]
Contractile function is synonymous with myocardial viability, several definitions exist based on the markers used by different cardiac imaging techniques: wall thickness, myocardial contractile reserve, myocyte cellular integrity (single-photon emission computed tomography (SPECT)), myocardial metabolism (positron emission tomography (PET)), and myocardial scar/fibrosis [4,5,6,7,8,9]
Summary
Cardiovascular magnetic resonance permits assessment of irreversible myocardial fibrosis and contractile function in patients with previous myocardial infarction. Left ventricular (LV) dysfunction is a common finding after myocardial infarction (MI) that is associated with high morbidity and mortality in patients with heart failure [1, 2] It is the extent of myocardial necrosis. (subendocardial and/or transmural) and the severity of myocardial dysfunction in the jeopardized myocardium that contribute to post-MI ventricular remodeling, but other pathophysiological pathways (e.g., neuroendocrine systems) involving the remote zones [3] In this clinical context, contractile function represents a key element in counteracting post-ischemic remodeling and avoiding progression of LV dysfunction and heart failure [4]. These two variables often are intermingled as they can coexist within the same myocardial segment, and, importantly, the likelihood of improvement in contractility after revascularization is predicted by the transmural extent of the scar, i.e., the lower the transmural extent of myocardial scar tissue, the higher the probability of functional recovery [10]
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