Trending Cardiac Biomarkers During Pregnancy in Women With Cardiovascular Disease

Clinical utility of cardiac biomarker testing during pregnancy in women with preexisting cardiac disease is not well known. We studied the levels and temporal trends of NT-proBNP (N-terminal pro-B-type natriuretic peptide) and hs-cTnI (high-sensitivity cardiac troponin I) throughout pregnancy in women with preexisting cardiac disease and sought to assess the association between NT-proBNP and hs-cTnI and pregnancy outcomes.

Three hundred seven pregnant women with preexisting cardiac disease were prospectively recruited. Mixed-effects linear regression analysis was used to compare the NT-proBNP and hs-cTnI levels between time periods and subgroups. Logistic regression analysis adjusted for maternal age and CARPREG II (Cardiac Disease in Pregnancy) risk score assessed the association between NT-proBNP levels and adverse events.

Geometric mean NT-proBNP (95% CI) was stable through pregnancy with a transient significant increase with labor and delivery (101.4 pg/mL [87.1-118.1], 90.2 pg/mL [78.5-103.6], 153.6 pg/mL [126.8-186.1], and 112.2 pg/mL [94.2-133.7] for first/second trimester, third trimester, labor/delivery and postpartum, respectively). We observed a statistically significant difference in the NT-proBNP between women with preserved versus decreased systemic ventricular function, structurally normal versus abnormal heart, modified World Health Organization class 1, 2 versus modified World Health Organization class 3, 4 and no congenital heart disease versus congenital heart disease. Compared to those without events, median (interquartile range) NT-proBNP levels were significantly higher in those who had heart failure (204 pg/mL [51-450] versus 55 pg/mL [31-97]; P=0.001) and preeclampsia (98 pg/mL [40-319] versus 55 pg/mL [31-99]; P=0.027). NT-proBNP, adjusted for age and CARPREG II risk score, was significantly associated with combined heart failure and preeclampsia (adjusted odds ratio, 2.14 [95% CI, 1.48-3.10] per log NT-proBNP increase; P<0.001). NT-proBNP <200 pg/mL had a specificity of 91% and negative predictive value of 95% in predicting combined heart failure and preeclampsia.

NT-proBNP remains steady over the course of pregnancy with a transient increase during labor and delivery with higher levels in subgroups of stable cardiac patients. NT-proBNP level of 200 pg/mL can be used in the diagnosis of heart failure/preeclampsia in the pregnant cardiac population.