(688) Effect of oral loop diuretics on postpartum blood pressure trajectories: a randomized-controlled trial secondary analysis

Objective:
In patients at risk for postpartum hypertension (PP HTN), physiologic volume shifts after delivery may contribute to hypertensive episodes. Diuretic therapy is proposed to limit this response without robust data to support efficacy. In this secondary analysis of a negative randomized trial (NCT04752475), we examined the effect of furosemide on longitudinal PP blood pressure (BP) patterns in patients at risk for PP HTN.

Study Design:
We analyzed data of normotensive patients at high risk for de novo PP HTN (dnPPHTN) randomized to daily furosemide or placebo from PP day 1-5. BP was monitored every 4-8 hours while inpatient, then by remote monitoring twice-daily for 6 weeks. The primary objective of this secondary analysis was comparison of BP trajectories between exposure groups. Secondary goals included exploring differential effects of furosemide on BP trends between those with or without dnPPHTN. Trends were assessed using local polynomial regression fitting. Linear mixed-effects models were used to examine temporal BP trajectories.

Results:
We analyzed 80 participants contributing 4129 PP BP readings. The furosemide group reached peak SBP earlier than the placebo group (PP day 8: 127.4 ± 14.9mmHg vs day 10: 120.7 ± 13.4mmHg) and reached peak DBP earlier (day 10: 83.1 ± 10.6mmHg vs day 12: 81.0 ± 10.3mmHg, Fig. 1). Participants who developed dnPPHTN had more pronounced acceleration in BP peak when randomized to furosemide vs placebo (SBP: day 8 vs 9; DBP: day 10 vs 14), whereas normotensive participants had no SBP difference (day 9, both groups) and a smaller DBP shift (day 10 vs 12, Fig. 2). Though there was no significant difference in the rate of dnPPHTN, median time to diagnosis was earlier in the furosemide group (PP day 3, IQR 3-6 vs day 5, IQR 5-5.5).

Conclusion:
In normotensive patients with PP HTN risk factors, administration of a 5-day course of oral furosemide led to earlier peak BP and earlier dnPPHTN detection. However, furosemide exposure did not influence dnPPHTN incidence, suggesting that PP fluid shifts are not the sole mechanism for pathophysiological BP changes in this population.