ACE inhibitors associated with improved in-hospital outcomes for CABG patients

Continuing angiotensin-converting enzyme (ACE) inhibitors, or adding them early after surgery, is associated with improved in-hospital outcomes for patients undergoing coronary artery bypass grafting (CABG), a study found.

In a prospective, observational study, researchers examined 4,224 patients undergoing CABG surgery. Patients were analyzed in four groups: continuation, that is, patients who were on ACE inhibitors pre- and postoperatively (21.7%, n=915); withdrawal, patients who took ACE inhibitors preoperatively but not postoperatively (21.8%, n=923); addition, patients who didn't take ACE inhibitors preoperatively but added them postoperatively (8.1%, n=343); and patients with no exposure to ACE inhibitors (48.4%, n=2,043). The primary outcome was a composite of cardiac, cerebral and renal events and in-hospital mortality. Results were published onlinepublished online June 18 by Circulation.

Compared to not using ACE inhibitors, continuous treatment with ACE inhibitors was associated with a significant reduction in the risk of nonfatal events (adjusted odds ratio [OR] for composite outcome, 0.69; P=0.009) and cardiovascular events (OR, 0.64; P=0.006). Adding ACE inhibitors after surgery compared to no use was also associated with a significantly lower risk of composite outcome (OR, 0.56; P=0.004) and cardiovascular events (OR, 0.63; P=0.04). Compared to withdrawal of ACE inhibitors, continuous treatment was associated with a lower risk of the composite outcome (OR, 0.50; P=0.001) as well as a decreased risk in cardiac and renal events (P<0.001 and P=0.005). There were no differences in in-hospital deaths or cerebral events based on ACE inhibitor usage.

The results indicate that withdrawing ACE inhibitors after CABG surgery is associated with nonfatal in-hospital events, while continuing ACE inhibitor treatment or adding it early after surgery is associated with better outcomes, the authors concluded. Given these findings, it is "alarming to learn that clinicians chose to acutely discontinue [ACE inhibitor] therapy in nearly 50% of patients following cardiac surgery. This pattern of practice was associated with major vascular complications. Acute withdrawal of [ACE inhibitor] therapy may be particularly harmful in the context of cardiac surgery….," they wrote.

Editorialistscaution that, as the study was observational, one can only note associations and not assume causation, and a randomized, controlled trial is needed. "As such, we should not yet conclude that withdrawal of [ACE inhibitors] necessarily causes increased post-operative complications," they wrote. For example, "If [ACE inhibitors] were withdrawn from patients at high risk of cardiovascular instability postoperatively, it may erroneously appear as if [ACE inhibitor] withdrawal is a cause of the postoperative cardiovascular events." Still, they said, the study is important "in that it forces providers to re-examine the practice of routinely discontinuing [ACE inhibitors] peri-operatively. Our advice to readers is to be open minded [and] stay tuned…."