Disturbed RAAS response to cardiac surgery in heart failure patients

Introduction Heart failure (HF) patients are prone to postoperative hemodynamic instability after cardiac surgery, possibly due to upregulated renin-angiotensin-aldosterone system (RAAS) activity. We evaluated perioperative RAAS activity in control and HF patients and its impact on acute kidney injury (AKI) incidence. Materials and Methods Pre-specified analysis of a prospective observational cohort study (VASOR). Plasma renin, angiotensinogen and aldosterone were measured perioperatively in 18 control and 18 HF patients. Results RAAS blocker use was identical in both groups. HF patients displayed a diminished preoperative renal function. AKI occurred in 1 control and 8 HF patients. Preoperatively, HF patients exhibited 5-fold higher renin and aldosterone levels, identical aldosterone/renin ratios, and modestly lower angiotensinogen levels than controls. During surgery, renin rose 10-fold higher in HF patients. Aldosterone increased proportionally, but was blunted when normalized for renin (aldosterone/renin ratio). This was not due to angiotensinogen depletion. Postoperatively, angiotensinogen increased 50% in both groups, allowing aldosterone to increase, despite a modest postoperative renin decline. Preoperative renin levels and the surgery-induced renin rise predicted postoperative AKI. Conclusions HF patients exhibit dysregulated RAAS responses to surgery may reflect impaired angiotensin I-angiotensin II conversion. Elevated renin signals RAAS dysregulation, identifying patients who might benefit from angiotensin II infusion. The Netherlands Trial Register (NTR5647); http://www.trialregister.nl/trialreg/admin/rctview.asp?TC=5647 .