Tolerance to ACE inhibitors after cardiac surgery

Several studies have shown angiotensin-converting enzyme (ACE) inhibitors to confer significant mortality and morbidity benefits in heart failure. First-dose hypotension may necessitate interruption of such therapy. This is more likely to occur if the ACE inhibitor is administered early after coronary artery bypass grafting (CABG). The purpose of this study was to analyse the haemodynamic tolerance to early post-operative treatment with perindopril and enalapril in patients with impaired renal and ventricular function.

Eighty one consecutive CABG patients with a previous myocardial infarction, impaired pre-operative left ventricular ejection fraction (LVEF) on ventriculography and moderately impaired renal function (serum creatinine of 115-150 micromol/l) were randomised into three groups to receive oral placebo, perindopril (4 mg) or enalapril (5 mg) once daily. Groups were subdivided into those with mild ventricular dysfunction (LVEF = 35-65%, n = 20) and significant ventricular dysfunction (LVEF < 35%, n = 7). Exclusion criteria included oliguria (<0.5 ml/kg per h) or inotrope dependance at the point of entry on the first post-operative day. Intolerance to ACE inhibitor was defined as hypotension (<95 mmHg systolic blood pressure or a decrease exceeding 25 mmHg in systolic blood pressure) leading to oliguria (<0.5 ml/kg per h) which was unresponsive to intravenous furosemide (20 mg). In such cases ACE inhibitor treatment was discontinued and patients commenced on dopamine.

In the groups with mild ventricular dysfunction (LVEF = 35-65%) perindopril was discontinued in 1/20 and enalapril in 4/20 patients (P = n.s). However, in the groups with significant ventricular dysfunction (LVEF < 35%) perindopril was discontinued in 2/7 and enalapril in 7/7 patients (P = 0.02).

Our results suggest that after CABG, patients with moderately impaired renal function and significant ventricular dysfunction do not tolerate ACE inhibitors well when these were commenced on the first post-operative day. However, perindopril was associated with less haemodynamic deterioration than enalapril and consequently may be advantageous in this setting. rights reserved.