Plasma Renin Activity Increases With Cardiopulmonary Bypass and is Associated With Vasoplegia After Cardiac Surgery

Objectives: To describe the trend in plasma renin activity over time in patients undergoing cardiac surgery on cardiopulmonary bypass, and to investigate if increased plasma renin activity is associated with postcardiopulmonary bypass vasoplegia. Design: A prospective cohort study. Setting: Patients were enrolled from June 2020 to May 2021 at a tertiary cardiac surgical institution. Patients: A cohort of 100 adult patients undergoing cardiac surgery on cardiopulmonary bypass. Interventions: None. Measurements and Main Results: Plasma renin activity was measured at 5 time points: baseline, postoperatively, and at midnight on postoperative days 1, 2, and 3. Plasma renin activity and delta plasma renin activity were correlated with the incidence of vasoplegia and clinical outcomes. The median plasma renin activity increased approximately 3 times from baseline immediately after cardiac surgery, remained elevated on postoperative days 0, 1, and 2, and began to downtrend on postoperative day 3. Plasma renin activity was approximately 3 times higher at all measured time points in patients who developed vasoplegia versus those who did not. Conclusions: In patients undergoing cardiac surgery on cardiopulmonary bypass, plasma renin activity increased postoperatively and remained elevated through postoperative day 2. Additionally, patients with vasoplegic syndrome after cardiac surgery on cardiopulmonary bypass had more robust elevations in plasma renin activity than nonvasoplegic patients. These findings support the need for randomized controlled trials to determine if patients undergoing cardiac surgery with high plasma renin activity may benefit from targeted treatment with therapies such as synthetic angiotensin II.