Preoperative treatment with renin-angiotensin system inhibitors (RASIs) does not help reduce the risk of postoperative atrial fibrillation (POAF), stroke, death or hospitalisation in the setting of cardiac surgery.

A systematic review of the evidence identified 11 relevant studies comprising almost 28,000 patients undergoing CABG or valve surgery who were allocated to either a RASI – angiotensin-converting enzyme inhibitor or angiotensin receptor blocker – or a control group.

The incidence of POAF was 26.1% in the RASI group versus 24.3% in the control group (OR 1.04) demonstrating no benefit from the drugs in reducing the risk of POAF.

The meta-regression analysis found only male sex was associated with increased POAF while the use of beta-blockers was associated with reduced POAF.

The incidence of secondary outcomes was similar in both groups such as stroke (1.8% v 2.0%), all-cause mortality (3.2% v 3.2%), and a composite of adverse cardiac event (30.6% v 28.9%). Duration of hospital stay was also similar in both groups.

The study said the specific mechanism for POAF had yet to be fully understood and there was an urgent clinical need to reduce this postoperative complication.

Evidence that RASIs might play a protective role in AF was largely in nonsurgical patients.

“This large-sample pooled analysis involving existing evidence suggests that preoperative treatment using RASIs does not appear to offer additional benefit in reducing the acute risk of POAF, stroke, mortality, and hospitalisation in the setting of cardiac surgery,” they said.

Professor Julien Smith, head of Cardiothoracic Surgery at Monash Health, told the limbic that RASIs were not prescribed routinely in Australia in advance of cardiac surgery as a prophylaxis against post-operative atrial fibrillation.

This practice was vindicated by the results of the meta-analysis, he said.

“However, many patients are already on beta-blockers prior to cardiac surgery but there is variable practice as to whether beta-blockers are prescribed as routine prophylaxis against post-operative atrial fibrillation. I suspect such would be in a minority.”