Heart rate variability as a predictor factor of the development of preeclampsia: systematic review of the literature

Abstract

Abstract Introduction Preeclampsia corresponds to one of the main causes of maternal and fetal morbidity and mortality worldwide. There are several studies in the literature that refer to heart rate variability (HRV) as a potential predictor factor for preeclampsia. However, a large number of these evidence shows wide heterogeneity in the results of the evaluated domains, which raises the need to develop new studies to demonstrate their predictive value and applicability. Purpose To determine if HRV is a predictor factor for the development of preeclampsia. Methods The electronic databases PUBMED, Google Scholar and EBSCO host, were searched for observational studies that measured the HRV in pregnant women, comparing the evolution towards the development or not of preeclampsia. Two independent reviewers extracted the data using a predesigned data collection form for their respective analysis in the statistical program STATA v.14. In each of the studies, clinical and statistical heterogeneity was assessed using the I2 test. Additionally, an overall effect measure was calculated based on the standardized mean difference. The Forest-plot graph was used to summarize the results of the study. Results The search identified 1661 articles of which 15 were included in this review. The variables that were associated with the development of preeclampsia from the standardized mean difference (SMD) with an I2 of 0.0% were High frequency (HF) in normalized units with a SMD of −0.45 (95% CI: −0.68, −0.22); Low frequency (LF) in ms2 with a SMD of 0.36 (95% CI: 0.04, 0.68) and SDNN in ms2 with a SMD of −0.43 (95% CI: −0.67, −0.18). Other variables that showed a significant standardized mean difference but with a higher heterogeneity were LF in normalized units with an I2 of 57.3%, a SMD of 0.45 (95% CI: 0.22, 0.68), and the Low frequency/High frequency (LF/HF) ratio with an I2 of 41.9% and a SMD of 0.41 (95% CI: 0.18, 0.64). Conclusion The findings of this review indicate that preeclamptic women present decreased vagal tone, evidenced in low HF and SDNN SMD values, and an increased sympathetic activity, shown in high LF and LF/HF ratio SMD values, compared to the healthy pregnant women. These findings open the discussion about if autonomic disturbances are a consequence or could be a cause associated with the develop of preeclampsia. Funding Acknowledgement Type of funding sources: None.