Intrapartum trends of NT-proBNP and hs-cTnT in patients with severe features of preeclampsia

Abstract

Background: Preeclampsia with severe features (SPE) is a multisystem syndrome associated with long-term cardiovascular morbidity. Serum concentrations of N-terminal B-type natriuretic peptide (NT-proBNP) and high sensitivity cardiac troponin-T (hs-cTnT) are sensitive markers of cardiac stretch and ischemia, respectively.

Objective: Our aim was to examine NT-proBNP and hs-cTnT in patients with SPE during labor. We hypothesized that patients with severe preeclampsia would have increased serum concentrations of these analytes as compared with normotensive laboring patients.

Study design: This was a prospective cohort study of intrapartum patients with SPE and normotensive controls. Patients were recruited at the time of SPE diagnosis or admission to the labor unit, and those with medical conditions that could predispose to baseline cardiac dysfunction were excluded. Serum from venous blood was collected for NT-proBNP and hs-cTnT measurement at three time points: 0-2 h, 4 h, and 12 h after admission. A mixed random effects regression model was used to compare analyte levels at each time point and to compare trends over time. The primary outcome was NT-proBNP concentration at each collection time point in patients with severe preeclampsia as compared to normotensive controls. Power analysis yielded a goal sample of 25 patients with a 12 h and at least 1 other sample in each arm. Two-tailed P values less than 0.05 were considered statistically significant. P value adjustment for multiple comparisons was performed.

Results: Of 78 patients analyzed, 36 had severe preeclampsia and 42 were normotensive controls with 25 in each cohort having a 12 h and at least 1 other sample. The NT-proBNP trend was significantly different in the two cohorts (P < 0.001). After adjustment for multiple comparisons, the mean serum concentration of NT-proBNP was elevated in the severe preeclampsia group at 0-2 and 4 h, but not at 12 h. After similar adjustment, detectable serum concentrations of hs-cTnT were more frequent in patients with severe preeclampsia at all three timepoints.

Conclusion: Intrapartum serum concentrations of NT-proBNP were elevated nearly twofold in patients with SPE when compared with normotensive controls, with the most pronounced differences found during early labor. Detectable but low serum concentrations of hs-cTnT were more common in women with severe preeclampsia as compared with normotensive controls. These findings suggest cardiac dysfunction with SPE may be present at the time of admission and contribute to features of maternal cardiovascular morbidity and mortality.

Keywords: Cardiac biomarkers; Hypertension; Natriuretic peptide; Preeclampsia; Troponin.