Association of myocardial fibrosis, B-type natriuretic peptide, and cardiac magnetic resonance parameters of remodeling in chronic ischemic cardiomyopathy

The left ventricular (LV) scar size detected by cardiac magnetic resonance (CMR) imaging in ischemic cardiomyopathy (IC) has been correlated with mortality. However, the associations among myocardial fibrosis, ventricular geometry, and physiologic measures of myocardial performance remain to be defined. A retrospective analysis of patients with stable chronic IC (LV ejection fraction ≤50%) who underwent CMR imaging from 2004 to 2010 and had plasma B-type natriuretic peptide (BNP) measured within 14 days of the CMR study was undertaken. A total of 38 patients met the criteria (mean age 66 ± 10 years; 31 men [82%]). The duration of IC was 67 ± 69 months. The CMR characteristics included LV dilation (LV end-diastolic dimension 62 ± 8 mm) and severe systolic dysfunction (LV ejection fraction 28 ± 11%). The average quantitated myocardial fibrosis was 20 ± 12% of the LV mass. When stratified by fibrotic mass, increased myocardial scar size was associated with increased LV cavity size (p = 0.007), lower LV ejection fraction (p = 0.04), and higher BNP (p = 0.013). In comparison, when stratified by median BNP (475 pg/ml), an elevated BNP level was associated, not only with LV size, function, and degree of fibrosis, but also with increased meridional wall stress (p = 0.002) and worse New York Heart Association functional class (p = 0.006). In conclusion, in chronic IC, quantitated myocardial fibrosis is associated with CMR structural and functional LV abnormalities. Elevated BNP levels are related to high-risk structural and functional CMR abnormalities and wall stress and functional status. Myocardial fibrosis appears to be related to plasma BNP through the processes of ventricular remodeling.