Beta-blockers before CABG not associated with better outcomes

Use of beta-blockers in patients who have not had a recent heart attack but are undergoing nonemergency coronary artery bypass grafting (CABG) surgery was not associated with better outcomes, a study found.

Preoperative beta-blocker therapy is a national quality standard, the authors noted. They conducted a retrospective analysis of the Society of Thoracic Surgeons National Adult Cardiac database of U.S. hospitals performing cardiac surgery from 2008 to 2012. The study included 506,110 patients undergoing nonemergency CABG surgery who had not had a heart attack in the previous 21 days or any other high-risk symptoms.

Results appeared online June 16 at JAMA Internal Medicine.

Of the 506,110 patients, 86.2% received preoperative beta-blockers within 24 hours of surgery. A propensity-matched analysis included 138,542 patients. There was no difference between patients who did and did not receive preoperative beta-blockers in rates of:

• operative mortality (1.12% vs. 1.17%; odds ratio [OR], 0.96; 95% CI, 0.87 to 1.06; P=0.38),
• permanent stroke (0.97% vs. 0.98%; OR, 0.99; 95% CI, 0.89 to 1.10; P=0.81),
• prolonged ventilation (7.01% vs. 6.86%; OR, 1.02; 95% CI, 0.98 to 1.07; P=0.26),
• any reoperation (3.60% vs. 3.69%; OR, 0.97; 95% CI, 0.92 to 1.03; P=0.35),
• renal failure (2.33% vs. 2.24%; OR, 1.04; 95% CI, 0.97 to 1.11; P=0.30), and
• deep sternal wound infection (0.29% vs. 0.34%; OR, 0.86; 95% CI, 0.71 to 1.04; P=0.12).

Patients who received preoperative beta-blockers within 24 hours of surgery did have higher rates of new-onset atrial fibrillation than patients who did not (21.50% vs. 20.10%; OR, 1.09; 95% CI, 1.06 to 1.12; P<0.001), the authors wrote.

“[Beta]-blockers are an important and effective tool in the care of patients undergoing cardiac surgery in specific clinical scenarios,” the authors wrote. “However, the empirical use of [beta]-blockers as recommended by the National Quality Forum (without physiologic goals i.e., adequate clinical drug levels) in all patients before CABG may not improve outcomes.”

In an invited commentary, the editorialist states that, because of 5 limitations of the study, physicians should continue to adhere to American College of Cardiology/American Heart Association guidelines for preoperative beta-blockade in CABG surgery. Limitations include the following:

• Short-term CABG mortality rates, which have decreased to about 1%, may no longer be a sufficiently sensitive outcome to assess the value of perioperative beta-blockade;
• The study excluded 28% of patients with isolated CABG because of a myocardial infarction within 21 days before surgery, thus eliminating patients with ST-elevation myocardial infarction (STEMI) and non-STEMI;
• Critical variables necessary to address the efficacy of perioperative beta-blockade are not present in the study, such the specific beta-blocker used, whether the patient was receiving long-term beta-blocker therapy, the exact timing and protocol for beta-blocker administration, and use of amiodarone hydrochloride;
• Substantial differences were noted in the baseline characteristics of the beta-blocker and non-beta-blocker groups; and
• Pharmacogenetic variation may affect the efficacy of preoperative beta-blockade.

“Important considerations include perioperative continuation of [beta]-blockade in patients receiving long-term therapy and administration and titration of [beta]-blockers to optimal heart rate and blood pressure in [beta]-blocker-naïve patients, initiated as long before surgery as possible (preferably weeks before in elective patients),” the commentary concluded.