Perioperative Management of Losartan
Discontinuation of losartan (and other ARBs/ACE inhibitors) on the day before surgery may be considered to reduce the risk of severe intraoperative hypotension, though this must be balanced against the reasonable alternative of continuing therapy through surgery. The evidence shows conflicting recommendations, with newer guidelines suggesting discontinuation is optional rather than mandatory.
Primary Recommendation
The 2017 ACC/AHA guidelines state that discontinuation of ARBs perioperatively may be considered (Class IIb, Level B-NR), while continuation is also reasonable (Class IIa, Level B). 1 This reflects genuine clinical equipoise in the evidence base.
Key Evidence Supporting Each Approach
Arguments for Discontinuation:
Intraoperative hypotension is significantly more common when ARBs are continued. A randomized trial of 37 patients showed those who received angiotensin II antagonists on the morning of surgery had more frequent hypotensive episodes (2±1 vs 1±1, p<0.01), longer duration of hypotension (8±7 min vs 3±4 min, p<0.01), and greater need for vasopressor support compared to those who discontinued the drug the day before. 2
A 2018 meta-analysis of 6,022 patients confirmed that withholding ACE-I/ARB therapy was associated with significantly less intraoperative hypotension (OR 0.63,95% CI 0.47-0.85). 3
The 2009 European Society of Cardiology guidelines suggest that transient discontinuation of ACE inhibitors before non-cardiac surgery in hypertensive patients should be considered (Class IIa, Level C). 1
Arguments for Continuation:
No difference in mortality or major adverse cardiac events (MACE) has been demonstrated between continuation and discontinuation strategies. The same 2018 meta-analysis showed no association with mortality (OR 0.97,95% CI 0.62-1.52) or MACE (OR 1.12,95% CI 0.82-1.52). 3
The 2017 ACC/AHA guidelines state it is reasonable to continue medical therapy for hypertension until surgery (Class IIa, Level C-EO), and if held, ARBs should be restarted as soon as clinically feasible postoperatively. 1
Practical Algorithm for Decision-Making
Recommend Discontinuation (24 hours before surgery) if:
- Major vascular surgery or procedures with high risk of significant hemodynamic instability 2
- Patient has baseline hypotension or is volume-depleted 2
- Limited anesthesia resources or concerns about managing intraoperative hypotension 3
Reasonable to Continue if:
- Minor or intermediate-risk surgery with stable hemodynamics expected 1
- Patient has heart failure with reduced ejection fraction where ARB discontinuation could worsen volume status 1
- Strong indication for ARB therapy (e.g., diabetic nephropathy, recent MI) and surgery cannot be delayed 1
Critical Management Points
If losartan is discontinued:
- Stop 24 hours before surgery (not just the morning of surgery). 2 The half-life of losartan is 2 hours, but its active metabolite has a half-life of 6-9 hours, requiring a full day for clearance.
- Resume as soon as clinically feasible postoperatively, typically when oral intake is tolerated and hemodynamics are stable. 1
If losartan is continued:
- Anticipate and prepare for intraoperative hypotension with readily available vasopressors. 3, 2
- Consider using direct-acting vasopressors (phenylephrine, norepinephrine) rather than indirect agents (ephedrine), as renin-angiotensin blockade may reduce responsiveness to indirect agents. 2
- Ensure adequate preoperative hydration. 2
Common Pitfalls
- Stopping losartan only on the morning of surgery is insufficient - the drug requires 24 hours for adequate clearance to reduce hypotension risk. 2
- Assuming hypotension from continued ARB therapy leads to worse outcomes - current evidence does not support increased mortality or MACE despite increased hypotension. 3
- Forgetting to restart ARBs postoperatively - prolonged discontinuation may lead to rebound hypertension or worsening of underlying conditions. 1
- Beta blockers and clonidine should never be abruptly discontinued perioperatively (Class III: Harm) - this is distinct from ARB management. 1