In the News | Surgery
Hospitals always strive to improve outcomes after cardiac surgery, but what practices help physicians and administrators achieve that goal? Recent research has shed light on practices that provide benefits as well as some that don’t. Below are summaries of key studies on cardiac surgery and CABG.

Stick with ACE inhibitors post-CABG

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Source: Siemens Healthcare, image courtesy of Columbia Radiology Imaging, Columbia, Mich.
Continuing or initiating angiotensin-converting enzyme inhibitor (ACEI) therapy early after CABG surgery reduces in-hospital complications while acute withdrawal of ACEI treatment increases the odds of cardiac and renal events, researchers reported (Circulation online June 19). Despite the benefits, they found that physicians withdrew ACEI therapy in about half of the patients after cardiac surgery.

Drenger et al designed a prospective, observational study of patients undergoing CABG surgery to determine if the continuation, addition or withdrawal of ACEI therapy affected outcomes. They identified 4,224 patients, among whom 1,838 received ACEIs before surgery and 2,386 received no ACEIs. They categorized them into four post-operative groups based on ACEI use: continuation of ACEI treatment, withdrawal of treatment, additional treatment and no treatment.

Continuous treatment lowered the adjusted odds of the composite outcome (cardiac, cerebral and renal events and in-hospital mortality) 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. Among the withdrawal group, the adjusted odds of cardiac and renal events were 127 percent and 113 percent higher, respectively.

Half of the patients who had received ACEI therapy before surgery had it discontinued postoperatively, a finding the authors called alarming. “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,” they wrote.

Acadesine: No benefit post-CABG

Administering the adenosine-regulating agent, acadesine, to intermediate- and high-risk patients undergoing CABG did not reduce their risk of all-cause mortality, stroke or left ventricular dysfunction, according to the RED-CABG trial (JAMA 2012;308(2):157-164). The study‘s primary outcomes—all-cause mortality, cases of nonfatal stroke and the need for mechanical support for severe left ventricular dysfunction (SLVD) through post-op day 28—were found in 5 percent of the study population with no significant differences between the placebo and acadesine groups.

Refusing transfusions? It’s OK

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Patients who refuse blood transfusions after undergoing cardiac surgery are not at an increased risk for surgical complications or death, according to a study (Arch Intern Med online July 2).

Pattakos et al compared the complication and long-term death rate of 322 Jehovah Witness patients with 87,453 non-Witnesses who underwent cardiac surgery at the Cleveland Clinic. Among non-Witnesses, 38,467 did not receive blood transfusions and 48,986 did.

Using propensity matching, they found similar risks for hospital mortality between the two groups, but Witnesses had lower rates of additional operations for bleeding, renal failure and sepsis compared with those who received blood transfusion after surgery. Witnesses also had lower rates of MI, complications and additional bleeding operations, as well as shorter hospital length of stay and ICU length of stay compared with those who received blood transfusions. Those who refused blood transfusion had higher rates of survival at one-year compared with those who underwent the treatment, 95 percent vs. 89 percent, respectively.

“[C]urrent extreme blood management strategies do not appear to place patients at heightened risk for reduced long-term survival,” the authors wrote. “It is important to examine care of a patient population managed differently not only out of concern for morbidity risk but also for possible adoption of management strategies that may benefit other patient groups.”

Surgeries fuel increase in acute dialysis

The use of acute dialysis after surgery increased three-fold between 1995 and 2009 and occurred primarily after cardiac and vascular surgery, according to a study (CMAJ online June 25). More than one-third of those who received acute dialysis died within 90 days after surgery.

Siddiqui et al identified 552,672 patients in Ontario who underwent elective surgery at 118 hospitals between 1995 and 2009. Surgeries were categorized as abdominal, cardiac, retroperitoneal, thoracic and vascular. Their primary outcome was acute dialysis. The secondary outcomes were death within 90 days of surgery and chronic dialysis for those who received acute dialysis and survived beyond 90 days.

They observed a three-fold increase in the use of dialysis, primarily due to vascular and cardiac surgeries. The authors attributed some of their findings to changes in the patient population. They wrote that there likely was a higher risk for acute kidney injury among older and sicker patients, and that the increasing use of less invasive procedures made these patients candidates for surgeries.

Key Stats | In this study population:
  • 0.4 percent of patients received acute dialysis within 14 days of surgery
  • Incidence of acute dialysis increased from 0.2 percent in 1995 to 0.6 percent in 2009, primarily among cardiac and vascular surgery patients
  • 42 percent of patients who received acute dialysis died within 90 days
  • Among survivors, 27.2 percent needed chronic dialysis
Source: CMAJ online June 25.