Association of central and peripheral blood pressure with cardiovascular biomarkers in women with preeclampsia

Abstract

Background: Hypertensive disorders of pregnancy (HDP) are major contributors to maternal and perinatal morbidity and mortality worldwide. Traditional diagnosis of hypertension relies on peripheral blood pressure (PBP), but recent studies suggest central blood pressure (CBP) may better predict cardiovascular outcomes. Cardiac biomarkers such as N-terminal pro B-type natriuretic peptide (NT-proBNP) and high-sensitivity cardiac troponin I (hs-cTnI) are established and widely utilised biomarkers in cardiovascular risk stratification, and it is known these biomarkers are elevated in patients with HDP. However, the relationship between these cardiac biomarkers, CBP, and maternal complications of HDP remains unclear. Additionally, the current clinical use of these markers in women with HDP is not well-documented. Aims: The aims of this thesis were to theoretically assess whether arterial stiffness in women with a history of HDP persists beyond the puerperal period. Additionally, the thesis aimed to evaluate the correlation between CBP and the PBP measured using the Microlife WatchBP Office Central, as well as the association between CBP and adverse maternal outcomes, and the association between serum levels of NT-proBNP and hs-cTnI and adverse maternal outcomes among pregnant black African women with HDP and normotensive controls. Lastly, the thesis sought to evaluate the likelihood of clinical practitioners incorporating additional clinical diagnostic markers into the management of preeclampsia. Methodology: This thesis had three main studies: a systematic review and meta-analysis, an experimental study, and an online survey. The systematic review followed PRISMA-P 2015 guidelines, conducting comprehensive searches across major databases to identify studies on arterial stiffness in women with HDP after delivery. Data were extracted, screened by independent reviewers, and meta-analyses were performed to compare arterial stiffness indices between women with and without HDP. The experimental study was a cross-sectional investigation at Nelson Mandela Academic Hospital, that consecutively recruited a total of 540 participants, consisting of 270 inpatients diagnosed with HDP and an equal number of 270 normotensive pregnant inpatients. Inclusion and exclusion criteria were rigorously applied, and all procedures and measurements were conducted with meticulous attention to accuracy and adherence to clinical guidelines. The survey targeted registrars and medical specialists in regional and tertiary maternity units, gathering insights via an online questionnaire about their experience and perspective on the use of cardiac biomarkers in women with preeclampsia. Data were statistically analysed, and ethical approvals were obtained for all components. Results: Women with a history of HDP showed significantly higher augmentation index and pulse wave velocity compared to normotensive controls in the systematic review. The Microlife WatchBP Office Central device demonstrated high reliability for blood pressure measurements, with coefficients of variation between 1.0–1.8% and intraclass correlation coefficients above 0.96. Peripheral and central systolic blood pressures were strongly correlated, with central systolic blood CSBP) of 116 mmHg and central diastolic blood pressure of 78 mmHg identified as diagnostic thresholds for hypertension in pregnancy. The median peripheral systolic blood pressure among eclamptic patients with mild peripheral hypertension was 138.0 mmHg (IQR: 133.0-148.0) while the CSBP level in the same group was in the severe range [145.0 mmHg (IQR: 140.0-150.0) mmHg]. Women with HDP and maternal complications had higher CBP, NT-proBNP, and hs-cTnI levels compared to those without complications. Among surveyed clinicians, 75.9% acknowledged the potential benefit of cardiac biomarkers for preeclampsia management. Conclusion: Arterial stiffness may remain elevated in women with a history of preeclampsia, suggesting a possible increased risk of long-term cardiovascular disease. CBP, NT-proBNP, and hs-cTnI are higher in women with HDP and maternal complications, supporting their potential roles in risk stratification and monitoring. CBP may be more informative than PBP in recognizing individuals who could be at higher risk of developing eclampsia. Incorporating CBP and these biomarkers may help strengthen screening and management strategies for hypertensive pregnancy disorders.