Chronic hypertension diagnosed by the American Heart Association and American College of Cardiology criteria is associated with increased risk of developing hypertensive disorders of pregnancy

Abstract

Background: ACOG uses a systolic blood pressure (SBP) ≥140 or diastolic blood pressure (DBP) ≥90 documented at <20 weeks of gestation to define chronic hypertension. In the nonpregnant state, the American Heart Association (AHA) and the American College of Cardiology (ACC) define chronic hypertension using lower diagnostic thresholds of SBP ≥130 or DBP ≥80. It remains unclear whether using more conservative guidelines in pregnancy improves identification of those at risk for gestational hypertension (GHTN) or preeclampsia (PRE).

Objective: We sought to investigate whether subjects with chronic hypertension based on the American Heart Association and American College of Cardiology criteria had an increased risk for gestational hypertension and preeclampsia than those without chronic hypertension.

Study design: We conducted a retrospective cohort study utilizing a clinical database at a diverse, large urban, safety-net hospital. Subjects aged 18 to 40 years with singleton gestations and first trimester prenatal care were included. We defined subjects that met the criteria for stage 1 chronic hypertension based on first trimester systolic blood pressure and diastolic blood pressure cutoffs satisfying the American Heart Association and American College of Cardiology criteria (systolic blood pressure ≥130 mm Hg or diastolic blood pressure ≥80 mm Hg). Those who did not meet these criteria had a systolic blood pressure <130 mm Hg and a diastolic blood pressure <90 mm Hg. We did not include those with chronic hypertension based on the American College of Obstetricians and Gynecologists criteria in this cohort (systolic blood pressure ≥140 mm Hg or diastolic blood pressure ≥90 mm Hg at <20 weeks); therefore, those who met the American Heart Association and American College of Cardiology criteria solely consisted of subjects with systolic blood pressure of 130 to 139 mm Hg and diastolic blood pressure of 80 of 89 mm Hg. By doing this, we were able to specifically investigate the increased risk for this specific population, which remains unclear. Diagnoses of gestational hypertension and preeclampsia were based on the established American College of Obstetricians and Gynecologists criteria. Preeclampsia included those with and without severe features. Tests for normality were performed. Student t-tests or rank sum tests were performed as appropriate for continuous variables; chi-square or Fisher's exact tests were performed for categorical variables. Generalized linear models were performed to calculate risk ratios while controlling for appropriate confounders.

Results: Of N=3354 subjects, 18% (n=629) were diagnosed with stage 1 chronic hypertension based on American Heart Association and American College of Cardiology criteria. Those with American Heart Association and American College of Cardiology stage 1 chronic hypertension had increased rates of gestational hypertension (35.4% vs 20%; P<.001) and preeclampsia (22.3% vs 10%; P<.001) than those without Stage 1 chronic hypertension based on these criteria. When controlling for maternal age, race, first trimester body mass index, pregestational diabetes, and substance use, those with the American Heart Association and American College of Cardiology stage 1 chronic hypertension had an almost 1.5-fold higher adjusted risk ratio of experiencing gestational hypertension (adjusted risk ratio, 1.49±0.10; P<.001) and almost 2-fold increased adjusted risk ratio of experiencing preeclampsia (adjusted risk ratio, 1.98±0.19; P<.001).

Conclusion: Our data suggest an increased risk for developing gestational hypertension and preeclampsia for subjects satisfying the American Heart Association and American College of Cardiology cutoff for stage 1 chronic hypertension. Future studies need to consider whether diagnosis of chronic hypertension in pregnancy should conform with American Heart Association and American College of Cardiology criteria, and if those with stage 1 chronic hypertension based on American Heart Association and American College of Cardiology criteria require the same preventative measures and interventions utilized by those diagnosed by American College of Obstetricians and Gynecologists criteria.

Keywords: American College of Cardiology; American Heart Association; gestational hypertension; preeclampsia; stage 1 hypertension.