Transitioning from ARNI to ACEI
When switching from an ARNI (sacubitril/valsartan) to an ACEI, you must implement a mandatory 36-hour washout period between the last dose of ARNI and the first dose of ACEI to prevent life-threatening angioedema. 1, 2
Critical Safety Requirements
The 36-hour washout is bidirectional and non-negotiable:
- Stop ARNI completely
- Wait a full 36 hours
- Only then initiate ACEI therapy
This washout period exists because both drugs affect the bradykinin pathway, and concurrent use dramatically increases angioedema risk 1, 2, 3.
Absolute Contraindications to ACEI After ARNI
Do not initiate an ACEI if the patient has:
- Any history of angioedema (from any cause, including previous ACEI/ARB/ARNI use) 1, 2
- Current angioedema symptoms
- Less than 36 hours since last ARNI dose 2
Clinical Context: Why This Switch Is Generally Not Recommended
This transition represents a step backward in guideline-directed medical therapy. The 2022 AHA/ACC/HFSA guidelines explicitly recommend ARNI over ACEI for chronic symptomatic HFrEF (NYHA class II-III) because ARNI reduces cardiovascular death and HF hospitalization by 20% compared to enalapril, with 16% reduction in all-cause mortality 1, 3, 4.
Valid Reasons to Switch from ARNI to ACEI:
- Cost/access barriers preventing ARNI continuation
- Symptomatic hypotension refractory to dose adjustment 1, 5
- Patient intolerance to ARNI not manageable with dose modification
- Acute kidney injury requiring temporary switch to shorter-acting agent
Practical Implementation Algorithm
Step 1: Verify the clinical necessity of switching (see valid reasons above)
Step 2: Administer the last dose of ARNI and document exact time
Step 3: Monitor during washout period:
- Blood pressure (risk of rebound hypertension)
- Volume status (may need temporary diuretic adjustment)
- Symptoms of HF decompensation
Step 4: After exactly 36 hours, initiate ACEI at standard starting dose:
- Enalapril 2.5 mg twice daily
- Lisinopril 2.5-5 mg daily
- Ramipril 1.25-2.5 mg daily
Step 5: Uptitrate ACEI to target doses per standard HF protocols
Common Pitfalls to Avoid
- Never overlap ARNI and ACEI - this is explicitly contraindicated 1, 2
- Don't rush the washout - 24 hours is insufficient; the full 36 hours is required based on pharmacokinetics 2, 3
- Don't assume prior ACEI tolerance predicts current tolerance - reassess renal function and potassium before initiating
- Don't forget to counsel patients about angioedema warning signs (tongue/lip/throat swelling, difficulty breathing)
Monitoring After Switch
Check within 1-2 weeks:
- Renal function (creatinine, eGFR)
- Serum potassium
- Blood pressure
- HF symptoms (may worsen given inferior efficacy of ACEI vs ARNI)
The evidence consistently shows that this transition moves patients away from optimal therapy 1, 4, 5, so document clear justification and consider strategies to return to ARNI when feasible.