A Pilot Study of Renin-Guided Angiotensin-II Infusion to Reduce Kidney Stress After Cardiac Surgery

BACKGROUND: Vasoplegia is common after cardiac surgery, is associated with hyperreninemia, and can lead to acute kidney stress. We aimed to conduct a pilot study to test the hypothesis that, in vasoplegic cardiac surgery patients, angiotensin-II (AT-II) may not increase kidney stress (measured by [TIMP-2][IGFBP7]). METHODS: We randomly assigned patients with vasoplegia (cardiac index [CI] > 2.1l/min, postoperative hypotension requiring vasopressors) and Δ-renin (4-hour postoperative-preoperative value) ≥3.7 µU/mL, to AT-II or placebo targeting a mean arterial pressure ≥65 mm Hg for 12 hours. The primary end point was the incidence of kidney stress defined as the difference between baseline and 12 hours [TIMP-2][IGFBP7] levels. Secondary end points included serious adverse events (SAEs). RESULTS: We randomized 64 patients. With 1 being excluded, 31 patients received AT-II, and 32 received placebo. No significant difference was observed between AT-II and placebo groups for kidney stress (Δ-[TIMP-2][IGFBP7] 0.06 [ng/mL]²/1000 [Q1-Q3, -0.24 to 0.28] vs -0.08 [ng/mL]²/1000 [Q1-Q3, -0.35 to 0.14]; P =.19; Hodges-Lehmann estimation of the location shift of 0.12 [ng/mL]²/1000 [95% confidence interval, CI, -0.1 to 0.36]). AT-II patients received less fluid during treatment than placebo patients (2946 vs 3341 mL, P =.03), and required lower doses of norepinephrine equivalent (0.19 mg vs 4.18mg, P <.001). SAEs were reported in 38.7% of patients in the AT-II group and in 46.9% of patients in the placebo group. CONCLUSIONS: The infusion of AT-II for 12 hours appears feasible and did not lead to an increase in kidney stress in a high-risk cohort of cardiac surgery patients. These findings support the cautious continued investigation of AT-II as a vasopressor in hyperreninemic cardiac surgery patients.