Withholding angiotensin receptor blockers (ARBs) for longer than 2 days after surgery is associated with a significantly increased risk of postoperative death, according to a study published in Anesthesiology.
“For non-cardiac surgery, ARBs are commonly stopped on the day of surgery because that makes it much easier to control blood pressure for a patient under general anaesthesia,” said Susan M. Lee, MD, University of California at San Francisco and the San Francisco VA Medical Center, San Francisco, California. “In many patients, they are often not restarted right away because of continued concerns about low blood pressure or kidney function. It turns out that this may be contributing to higher postoperative mortality.”
The authors analysed the medical records of 30,173 VA patients nationwide who underwent inpatient non-cardiac surgery between 1999 and 2011 and who were regularly prescribed an ARB. Almost 34% were not put back on ARBs within 2 days after surgery.
After adjusting for other variables, results showed that patients who were not put back on ARBs within 2 days after surgery were up to 1.5 times more likely to die within 30 days compared with patients whose ARB prescriptions were resumed within 2 days.
The researchers did not look at possible reasons for the increased risk, but they did find that the patients whose ARBs were restarted sooner had reduced rates of infections, pneumonia, heart failure, and kidney failure.
“Since ARBs are known to reduce inflammation, this tells us that post-operative inflammation is probably contributing to increased mortality in patients who aren’t put back on ARBs right away,” said Dr. Lee.
To their surprise, the authors also found that mortality risk associated with ARB withholding was even higher in patients aged younger than 60 years.
“However, we know that younger people have a more pronounced inflammatory response, so this makes sense,” said Dr. Lee.
She noted that the optimal time for restarting ARBs still needs to be determined by future research.
“We may find that continuing ARBs right through the day of surgery is better than stopping even for 1 day,” she said. “The next logical research step would be to conduct a prospective study, where we deliberately compare a group in which we stop and then resume ARBs and a group in which we don’t stop them at all.”