Harms of BP lowering drugs before surgery may outweigh the benefits

The long-standing controversy around whether to continue or withhold renin angiotensin antagonists (RAAs) before non-cardiac surgery has chalked up new evidence that favours withholding the therapy before an operation.

Doctors at the Princess Alexandra hospital in Queensland found that patients undergoing elective joint replacements who were receiving RAAs in the lead up to their surgery had a higher incidence of intraoperative hypotension compared to patients not receiving the blood pressure lowering agents (76% vs 46% respectively).

Speaking to the limbic Professor Ian Scottlead author of the retrospective case controlled study of 230 patients, said although the hypotensive episodes were treated promptly acute kidney injury occurred in more than 1 in 10 patients studied and MACCE occurred in more than 1 in 20 patients receiving RAAs.

“All the adverse events tended to appear in patients who had intra operative hypotension so we think it’s a signal that the drugs may be harmful,” said Dr Scott who is Director of Internal Medicine at the Brisbane based hospital.

He said the findings prompted the hospital to review its perioperative guidelines, which now recommend withholding the agents for 24 hours prior to surgery in the absence of uncontrolled hypertension.

Results from a prospective randomised controlled trial would be needed to unequivocally show that RAAs were associated with harm in the perioperative setting, Professor Scott noted.

However, he said there was still ‘reasonably compelling’ evidence to indicate that the potential harm of withholding RAAs is likely to be very small while the harm of continuing them is not insignificant.

“Perhaps physicians may want to be a little more circumspect in continuing these agents at the time of surgery, particularly in people who are at higher risk of being harmed by a sudden drop in blood pressure during the operation.”

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