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Patients with hypertension who are taking beta-blockers have after noncardiac surgery, a large observational study found.

The study appears to support current guidelines against using beta-blockers in the initial treatment of essential hypertension and may offer a contribution to the .

Danish researchers analyzed countrywide data for more than 55,000 patients with hypertension taking at least two blood pressure drugs who underwent noncardiac surgery. At 30 days, the event rates were significantly higher in patients who were taking a beta-blocker:

• For major adverse cardiovascular events, 1.32% versus 0.84% (P<0.001)
• For mortality, 1.93% versus 1.32% (P<0.001)

There were some important differences between the groups, including a larger proportion of women in the beta-blocker group. The overall findings remained significant after adjusting for differences between the groups. The paper was published in JAMA Internal Medicine.

, of the University of Michigan in Ann Arbor, who was the chair of the 2015 update to the American Heart Association/American College of Cardiology guidelines for perioperative cardiovascular evaluation for noncardiac surgery, warned that this was a very "dangerous study to interpret."

He said there were three different ways to interpret the study, only one of which is that beta-blockers are more dangerous than other drugs in the perioperative setting.

One interpretation is that the use of a multivariate analysis to adjust for various factors requires extreme caution, he said. It is entirely possible that the results are due to the fact that the patients taking beta-blockers were sicker than patients taking other drugs.

Another interpretation is based on the now-accepted understanding that beta-blockers are less effective antihypertensive agents, Eagle said. In this case, the perioperative complications might be a result of the patients having more problems because of their less well-controlled hypertension.

Eagle's third interpretation was that the sympathetic nervous system may play an important role if there is a problem during surgery, because "one of the ways our body gets out of that problem is by increasing heart rate." Inhibiting the sympathetic nervous system with beta-blockers in this context "could be potentially catastrophic," he said.

But, said Eagle, on the basis of this observational study, "I don't feel you can draw any conclusion from this at all."

, of Mount Sinai in New York City, said that the study provides further confirmation that "hypertension is an inappropriate indication for beta-blockade, particularly in the elderly."

"In this day and age, no physician in his or her right mind should treat uncomplicated hypertension in the elderly with a beta-blocker," he said. "These provocative findings suggest that even in combination, beta-blockers are inappropriate for the treatment of hypertension."