BACKGROUND: 

Hyperreninemia after cardiac surgery is associated with cardiovascular instability. Angiotensin II (AT-II) could potentially attenuate hyperreninemia while maintaining target blood pressure. This study assesses the association between AT-II usage and renin levels in cardiac surgery patients with postoperative hyperreninemia and vasoplegia.

METHODS: 

Between September 2020 and March 2021, we retrospectively identified 40 cardiac surgery patients with high Δ-renin levels (4 hours after cardiopulmonary bypass [CPB] minus preoperative levels) (defined as higher than 3.7 µU/mL) and vasopressor use who received a vasopressor therapy with either AT-II or continued norepinephrine alone. The primary outcome was the renin plasma level at 12 hours after surgery, adjusted by the renin plasma level at 4 hours after surgery.

RESULTS: 

Overall, the median renin plasma concentration increased from a baseline with median of 44.3 µU/mL (Q1–Q3, 14.6–155.5) to 188.6 µU/mL (Q1–Q3, 29.8–379.0) 4 hours after CPB. High Δ-renin (difference between postoperation and preoperation) patients (higher than 3.7 µU/mL) were then treated with norepinephrine alone (median dose of 3.25 mg [Q1–Q3, 1.00–4.75]) or with additional AT-II (norepinephrine dose: 1.33 mg [Q1–Q3, 0.78–2.04]; AT-II dose: 0.34 mg [Q1–Q3, 0.29–0.78]). At 12 hours after surgery, AT-II patients had lower renin levels than standard of care patients (71.7 µU/mL [Q1–Q3, 21.9–211.4] vs 130.6 µU/mL [Q1–Q3, 62.9–317.0]; P = .034 adjusting for the renin plasma level at 4 hours after surgery).

CONCLUSIONS: 

In cardiac surgery patients with hypotonia and postoperative high Δ-renin levels, AT-II was associated with reduced renin plasma levels for at 12 hours and significantly decreased norepinephrine use, while norepinephrine alone was associated with increased renin levels. Further studies of AT-II in cardiac surgery appear justified.