Abstract 80: Correlation of N-terminal pro-BNP Release with Myocardial Involvement in Acute Kawasaki Disease

Abstract

N-terminal pro-BNP (NT-proBNP) is elevated at the onset of Kawasaki Disease (KD). This is based on the hypothesis of immune myocardial inflammation. We sought to study the relationship between NT-proBNP and cardiac function in KD. Parameters of myocardial involvement determined by ECG (PR and QTc intervals, QT dispersion, R-T axis) and by echocardiogram (systole and diastole) were correlated with levels of NT-proBNP in the acute (1 week), sub-acute (2-3 months) and chronic (6 months to 1 year) phases of KD. KD patients were compared to a febrile group. KD patients were further subdivided into 2 groups according to the levels of NT-proBNP; normal NT-proBNP (NT-proBNP Z-score < 2), or elevated NT-proBNP (Z-score ≥ 2). There were 56 subjects (14 controls, 19 KD-1 and 23 KD-2 patients), with similar age at assessment (3.8±4.3 vs. 3.3±2.3 years-old, p=0.609). Myocardial contractility was significantly lower in KD patients in the acute phase with an ejection fraction of 57.4±7.5% compared to CTL 61.9±6.5%; p=0.049). Myocardial dysfunction was more significant in KD with high NT-proBNP compared to those with normal NT-proBNP, (shortening fraction Z-score of-1.6±1.5 versus -0.5±1.5; p=0.025) QTc interval was longer in KD compared to febrile CTL (412.3±21.0 mS vs. 390.6±14.6 mS, respectively; p=0.009). In contrast, there were no significant differences for left ventricular mass index (p=0.935) or LV end-diastolic diameter (p=0.565). Likewise, there were no significant differences for the PR interval (p=0.344), QT dispersion (p=0.288) or R-T axis (p=0.577). Otherwise, there was a significant correlation between coronary artery involvement (CA z-score ≥ 2.5) and the likelihood of lower LV ejection fraction (p=0.049) and higher NT-proBNP z-score (p=0.043), but no correlation with normalized LV shortening fraction (p=0.16) or QTc (p=0.14). The anomalous findings disappear in the sub-acute phase. On the other hand, a lengthening of QTc interval in the acute phase, irrespective of NT-proBNP status, resolves after 2-3 months. In acute KD, there is a reduction in myocardial function, to a higher extent in cases with elevated NT-proBNP. This correlates with coronary artery involvement. KD patients with elevated NT-proBNP z-score may warrant careful follow-up.