Docs discontinue ACE inhibitors post-CABG despite benefits

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cardiology, surgery, error, blood - 284.85 Kb

Continuing or initiating angiotensin-converting enzyme inhibitors (ACEI) therapy early after coronary artery bypass (CABG) surgery reduces in-hospital complications while acute withdrawal of ACEI treatment increases the odds of cardiac and renal events, researchers reported in a study published online June 19 in Circulation. Despite the benefits, they found that physicians withdrew ACEI therapy in about half of the patients after cardiac surgery.

Benjamin Drenger, MD, of Hadassah-Hebrew University Medical Center in Jerusalem, and colleagues designed a prospective observational study of patients undergoing CABG surgery to determine if the continuation, addition or withdrawal of ACEI therapy affected outcomes. They noted that ICEI may offer prophylactic benefits after cardiac surgery that protect against cerebrovascular and renal events and consequently help reduce complications. But, the perioperative use of ACEI has been erratic, they wrote, in part due to reports linking ACEI to protracted vasoplegia.

They used Ischemia Research and Education Foundation (IREF)/McSPI EPI-II, a longitudinal study that prospectively enrolled patients from 72 medical institutions in 17 countries who were admitted for CABG surgery using cardiopulmonary bypass. The primary outcome was the composite of cardiac, cerebral and renal events and in-hospital mortality.

For this study, the researchers identified 4,224 patients, among whom 1,838 received ICEI therapy before surgery and 2,386 received no ACEI therapy. They categorized them into four post-operative groups based on ACEI use: continuation of ACEI treatment (915 patients), withdrawal of treatment (923 patients), additional treatment (343 patients) and no treatment (2,043 patients).

The patients who were not on ACEI therapy before surgery had fewer preoperative cardiovascular risk factors compared with those on the therapy. The two groups had similar intraoperative clinical and surgical characteristics.

They found that continuous treatment lowered the adjusted odds of the composite outcome and of a cardiovascular event by 31 percent and 36 percent, respectively. Only 14.4 percent of the patients had ACEI treatment added after surgery, but its addition lowered the odds of the composite outcome by 44 percent, mostly due to a decrease in cardiovascular events.   
“The use of ACEI was associated mostly with better cardiac outcome , with a near 40 percent reduction in odds of both postoperative CHF [congestive heart failure] and MI [myocardial infraction],” Drenger and colleagues wrote.

But among the withdrawal group, the adjusted odds of cardiac and renal events were 127 percent and 113 percent higher. This group also had the poorest outcome, with 71 percent event-free one month after surgery.

“According to our findings, ACEI therapy in cardiac surgery is most valuable when it is provided perioperatively and, importantly, its acute withdrawal after surgery can be associated with poor outcomes,” they wrote. “In comparing the continuation group with the acute withdrawal cohort we observed a 50 percent reduction of odds in overall complication, inclusive of a 61 percent and a 46 percent in CHF and MI.”

Half of the patients who had received ACEI therapy before surgery had it discontinued postoperatively, a finding the authors called alarming. “This pattern of practice was associated with major vascular complications,” they wrote. “Acute withdrawal of ACEI therapy may be particularly harmful in the context of cardiac surgery as an abrupt rebound in ACE activity may further compromise microcirculatory flow.”

Drenger and colleagues pointed to the study’s observational design as a limitation. They also noted a difference between the clinical characteristics between the patients who before surgery received ACEI treatments and those who did not.

Their results showed that continuing or adding ACEI therapy after CABG surgery with cardiopulmonary bypass was associated with improved in-hospital cardiovascular and renal outcomes while discontinuing ACEI treatment postoperatively was associated with poor in-hospital outcomes, they summarized.