Correlation between microvascular dysfunction and B-type natriuretic peptide levels in non-ischemic heart failure patients with cardiac fibrosis.

BACKGROUNDS: The relationship between microvascular dysfunction and plasma B-type natriuretic peptide (BNP) levels remains unclear in heart failure (HF) patients with cardiac fibrosis.
METHODS: This study evaluated 55 consecutive non-ischemic HF patients in an effort to determine the relationship between endothelial independent coronary microvascular dysfunction and plasma BNP levels, as well as whether each measure is correlated with myocardial fibrosis. We evaluated plasma BNP levels in patients with stable HF. We used cardiac catheterization to measure trans-cardiac BNP release levels, measuring from the coronary sinus and the aortic root, and coronary flow reserve (CFR). Patients also underwent cardiac magnetic resonance imaging to evaluate for the presence of late gadolinium enhancement (LGE), as an indicator of cardiac fibrosis.
RESULTS: CFR in cardiac catheterization was significantly and inversely correlated with plasma BNP levels (r=0.336, p=0.012) and trans-cardiac BNP release levels (r=0.347, p=0.041). Thirty-three patients were LGE-positive. CFR was significantly correlated with plasma BNP levels in the LGE-positive group (r=0.349, p=0.046), but this correlation was not significant in the LGE-negative group. (r=0.338, p=0.125). Multivariate logistic regression analysis revealed that a plasma BNP levels >180pg/ml at stable HF condition was significant and independent predictor of CFR<2.5 in all patients (p=0.035, odds ratio: 5.2, 95% confidence interval: 1.1-29.0), and in the LGE-positive group (p=0.040, odds ratio: 5.4, 95% confidence interval: 1.1-27.2).
CONCLUSIONS: In non-ischemic HF patients especially those with cardiac fibrosis, endothelial independent microvascular dysfunction is closely correlated with plasma BNP levels, and ventricular wall tension.