Beta-blockers may increase cardiovascular risks in surgery for hypertensive patients

Patients with uncomplicated hypertension who undergo non-cardiac surgery may be at higher risk of a major adverse cardiovascular event (MACE), including death, if they are being treated with a beta-blocker, according to results of a Danish study.

The researchers, led by Mads Jørgensen, of the department of cardiology, Gentofte Hospital, University of Copenhagen, Denmark, warn that patients aged over 70 years, male patients and those undergoing acute surgery — rather than elective — are most at risk.

“Perioperative management of patients with hypertension should receive specific attention in clinical practice and future guidelines,” the researchers recommend.

The study, published in JAMA Internal Medicine
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on 5 October 2015, involved an analysis of hospital records and post-hospital drug therapy of patients who had uncomplicated hypertension and underwent non-cardiac surgery in Denmark between 2005 and 2011. The patients were treated with at least two antihypertensive drugs: beta-blockers, thiazides, calcium antagonists or renin-angiotensin system [RAS] inhibitors.

The researchers considered 14,644 patients who had received beta-blockers and another 40,676 patients who had been given other antihypertensive drugs. They found that a MACE occurred within 30 days of surgery in 1.3% of patients treated with beta-blockers compared with 0.8% of patients who did not use beta-blockers (P<0.001).

“All regimens that included a beta-blocker were associated with a statistically significant increased risk of MACE and all-cause mortality, compared with a regimen of RAS inhibitors and thiazides, with the exception of patients treated with beta-blockers and two other antihypertensive drugs,” say the researchers. Patients treated with any combination of other antihypertensive drugs were not at increased risk of MACE or mortality, compared with the reference, they found.

Risk of MACEs associated with beta-blocker use seemed especially pronounced for patients aged at least 70 years (number needed to harm [NNH] 140, 95% confidence interval [CI] 86–364), for men (NNH 142, 95% CI 93–195) and for patients undergoing acute surgery (NNH 97, 95% CI 57–331), compared with patients younger than 70 years, women and patients undergoing elective surgery, respectively.

Sotiris Antoniou, consultant pharmacist in cardiovascular medicine at Barts Health NHS Trust in London, who was not involved in the study, says current recommendations for non-cardiac surgery suggest that patients already on beta-blockers should continue taking them and that preoperative initiation of beta-blockers may be considered in certain patients scheduled for high-risk surgery. Beta-blockers are not recommended for patients scheduled for low-risk surgery, he says.

“Does this study change the guidelines,” Antoniou asks. “Not yet, as this is an observational study and so many factors that may influence outcome, such as heart rate, blood pressure, hypotension perioperatively, are not reported.” However, he says further investigations are needed to ensure guidance is clear.