Measurement of aortic augmentation index in pregnant women with raised blood pressure and subsequent outcomes: a preliminary prospective cohort study

Objective: Preeclampsia is associated with arterial dysfunction and augmentation index (AIX%) is an established indicator of arterial dysfunction. Our aim was to investigate the relationship of AIX% with time-to-delivery and other outcomes in women admitted to an antenatal triage unit. Methods: We recruited 28 women with singleton pregnancies attending antenatal triage ward for assessment of hypertension. After 10 min rest, seated brachial blood pressure (Omron HEM-757) and AIX% (SphygmoCor applanation tonometry pulse wave analysis, PWA) were measured by a single investigator; other clinicians remained blinded to PWA results. Routine assessment included cardiotocography, urine analysis and blood tests. Subsequent outcomes were extracted from the obstetric records. Results: Mean AIX% was 19.7% (SD 11.5; range -4% to +36%), maternal age 31 years, gestation 37 weeks, brachial BP 145/95, proteinuria 39%. Nine women had preeclampsia at assessment and six subsequently developed preeclampsia. Median time-to-delivery was 10 d (IQR 1.6-25 d) and was shorter for AIX% ≥ 20% (median 8.9 versus 19.8 d). AIX% was higher with preeclampsia (24.0%; SD 9.5) versus gestational hypertension (15.2%; SD 12.4); absolute difference 8.8% (95%CI 0.1-17.5; p = 0.05). A one-point higher AIX% (adjusted for age, urate and gestation) was associated with 0.3 d (95%CI -0.5 to 0.0; p = 0.06) reduced time-to-delivery. A higher AIX% was also associated with induction for preeclampsia, severe preeclampsia, peripartum-anti-hypertensives and discharge-on-anti-hypertensives. Area under the curve (AUC) for AIX% predicting preeclampsia was 0.80 (95%CI 0.59-1.00; p = 0.04). Conclusion: AIX% is associated with time-to-delivery and other outcomes in pregnancy.