A Highly Sensitive Regulatory System of Plasma B-Type Natriuretic Peptide to Ischemic Heart Disease Determined by Intracoronary Pressure Measurement

Background: B-type natriuretic peptide (BNP) is a biomarker of heart failure, however, the response of BNP to cardiac ischemia is still unclear. Therefore the myocardial ischemic effect on BNP by intracoronary pressure measurement in patients with suspected cardiac ischemia was investigated. Methods: The baseline distal-to-aortic pressure ratio (Pd/Pa) and fractional flow reserve (FFR) were examined in 167 patients with the intermediate coronary stenosis. Results: A significant inverse correlation between Pd/Pa and LogBNP became clear only in the patients with FFR ≤ 0.80 but not in those with FFR > 0.08. To examine a causative contribution of Pd/Pa to LogBNP in patients with FFR ≤ 0.08, the covariance structure analysis were performed. The Pd/Pa causatively affected LVEF (standard regression coefficient: β = −0.458, P < .001) and LogBNP (β = 0.394, P = .002). In order to examine a causative role of BNP to coronary vasodilation, another path model by using a value dividing FFR by Pd/Pa (FFR/Pd/Pa) as an index of hyperemia response was performed. A significant contribution of LogBNP to FFR/Pd/Pa (β = 0.353, P = .045) and also significant positive correlation between these factors were showed that, as the LogBNP increased, the value of FFR/Pd/Pa approached toward 1.0 but fell short of 1.0, suggesting an insufficient secretion of BNP for full coronary vasodilation. Conclusion: This study showed that BNP finely responded to the degree of cardiac ischemia, which should work to alleviate increased coronary arterial tonus.