Perioperative β-blockade was associated with lower 30-day mortality in patients with three to four cardiac risk factors undergoing noncardiac surgery (NCS), but with increased mortality in patients with no cardiac risk factors, according to a retrospective cohort study published in May JAMA Surgery.
“Perioperative β-blockade is widely accepted in patients who undergo cardiac surgery,” write Mark L. Friedell, MD, from the University of Missouri-Kansas City School of Medicine, and colleagues. “However, its use in patients undergoing [NCS] is controversial.”
“Our hypothesis was that β-blockade is beneficial in patients at high cardiac risk but may be harmful in those with little or no risk,” they continue.
In patients at low risk for cardiac events, use of β-blockade before or during NCS carries increased risk for stroke and hypotension. The goal of this retrospective observational analysis was to examine the effect of perioperative β-blockade on patients undergoing NCS, particularly among those with no cardiovascular risk factors.
The study cohort consisted of 326,489 patients undergoing NCS surgery (n = 314,114) or cardiac surgery (n = 12,375) from October 1, 2008, through September 31, 2013, at Veterans Affairs hospitals.
The investigators calculated a 4-point cardiac risk score by assigning 1 point each for renal failure, coronary artery disease, diabetes mellitus, and surgery in a major body cavity. Among patients with three or four cardiac risk factors who had NCS, β-blockade at any time between 8 hours before surgery and 24 hours postoperatively significantly lowered the odds ratio for unadjusted 30-day surgical mortality (odds ratio, 0.63; 95% confidence interval, 0.43 – 0.93).
However, β-blockade had no effect on patients with one or two cardiac risk factors, and it was associated with significantly increased mortality in patients with no risk factors (odds ratio, 1.19; 95% confidence interval, 1.06 – 1.35).
Unadjusted 30-day mortality rates for NCS among patients not receiving β-blockers were 0.5% for patients with no cardiac risk factors, 1.4% for those with one or two risk factors, and 6.7% for those with three or four risk factors. Among patients treated with β-blockers, these rates were 1.0%, 1.7%, and 3.5%, respectively.
“β-blockade is beneficial perioperatively for patients with 3 to 4 cardiac risk factors undergoing NCS but not in patients with 1 to 2 cardiac risk factors,” the study authors write. “Most important, the use of β-blockers in patients with no cardiac risk factors appears to be associated with a higher risk of death, which has, to our knowledge, not been previously reported.”
Limitations of this study include retrospective design, use of a Veterans Affairs population consisting predominantly of men, and lack of data regarding use of specific drugs, the causes of death, and the number of strokes. In addition, it is unclear whether the patient was first given the β-blocker in the hospital or at home, whether it was given preoperatively or postoperatively, and whether it was given for treatment of a complication.