Plasma Angiotensin Levels and Postoperative Hypotension in Patients With and Without Chronic Heart Failure Undergoing Cardiac Surgery

The renin-angiotensin-aldosterone system (RAAS) is essential to cardiovascular homeostasis, particularly in heart failure (HF) and cardiogenic shock states. Relative angiotensin II depletion is a potential mechanism for postoperative hypotension and may be potentiated by pre-existing HF. The availability of exogenous AT2 allows for tailored vasoplegia management in a state of RAAS dysregulation. This prospective, single-institution pilot study aimed to characterize the expected reduction in angiotensin II (AT2) and angiotensin I (AT1) levels following cardiopulmonary bypass (CPB) in patients with and without chronic systolic HF, with enrollment of 10 patients in each arm. Preoperative AT2 and AT1 levels were significantly higher in patients with HF and remained so following cardiac surgery. A lower postoperative AT2 correlated with lower mean arterial pressure and a trend toward higher pressor requirements in HF patients only. No association was seen in HF or non-HF patients between CPB time and the change in AT1, AT2, or their ratio. Taken together, this pilot study suggests a role for characterizing RAAS function in patients with HF undergoing cardiac surgery for prediction and treatment of postcardiotomy vasoplegia.