In a patient with symptomatic heart failure with reduced ejection fraction who is stable on an ACE inhibitor or ARB, how should I initiate and titrate an angiotensin‑receptor neprilysin inhibitor (ARNI) (sacubitril/valsartan)?

ARNI Initiation and Titration in HFrEF Patients

In patients with symptomatic HFrEF stable on an ACE inhibitor or ARB, switch to sacubitril/valsartan 49/51 mg twice daily after a mandatory 36-hour washout period from the ACE inhibitor, then double the dose every 2-4 weeks to reach the target of 97/103 mg twice daily. 1, 2

Critical Safety Requirements Before Switching

Mandatory 36-hour washout period: You must wait at least 36 hours between the last ACE inhibitor dose and the first ARNI dose to prevent life-threatening angioedema 1, 2. This is a contraindication, not a suggestion. ARBs do not require a washout period.

Absolute contraindications:

• Any history of angioedema (with ACE inhibitor, ARB, or otherwise) 1, 2
• Concomitant ACE inhibitor use 2
• Concomitant aliskiren use in diabetic patients 2

Initial Dosing Strategy

Standard Initiation (Most Patients)

Start sacubitril/valsartan 49/51 mg twice daily if the patient was on:

• High-dose ACE inhibitor (e.g., enalapril ≥10 mg twice daily) 3, 2
• High-dose ARB (e.g., valsartan ≥160 mg total daily) 3, 2

Lower Starting Dose (24/26 mg twice daily)

Use half the standard starting dose in these specific situations 3, 2:

• Not currently on ACE inhibitor or ARB (de novo initiation)
• Previously on low-dose ACE inhibitor or ARB
• Severe renal impairment (eGFR <30 mL/min/1.73 m²)
• Moderate hepatic impairment (Child-Pugh B)
• Age ≥75 years (consider, though not absolute)
• Borderline blood pressure (systolic ≤100 mmHg)

Titration Protocol

Double the dose every 2-4 weeks as tolerated 1, 2:

• 24/26 mg twice daily → 49/51 mg twice daily → 97/103 mg twice daily (target)
• OR 49/51 mg twice daily → 97/103 mg twice daily (target)

The target maintenance dose is 97/103 mg twice daily for all patients who can tolerate it 2. This is where the mortality and morbidity benefits are maximized from the PARADIGM-HF trial 1.

Managing Common Barriers to Titration

Hypotension

• Most common side effect, especially compared to ACE inhibitors 1
• If patient is non-congested with stable clinical profile, empirically reduce loop diuretic dose before ARNI initiation 3
• Ensure patient is not volume-depleted at initiation (up to 25% developed hypotension in PIONEER-HF) 3
• Symptomatic hypotension is manageable; asymptomatic low blood pressure alone should not prevent titration

Renal Function Changes

• Monitor creatinine and potassium, but mild increases should not automatically stop therapy
• Only severe renal impairment (eGFR <30) requires dose adjustment at initiation 2

Hyperkalemia

• Monitor potassium levels during titration
• Comparable rates to ACE inhibitors in trials 1

De Novo Initiation (No Prior ACE Inhibitor/ARB)

You can initiate ARNI directly without prior ACE inhibitor or ARB exposure 1, 3. Recent data supports this approach as safe and effective, simplifying management rather than requiring ACE inhibitor run-in first 3. Start at 24/26 mg twice daily in ACE inhibitor/ARB-naïve patients 2.

Inpatient Initiation

ARNI can and should be initiated during hospitalization for acute decompensated HF before discharge once the patient is hemodynamically stabilized 1, 3. The PIONEER-HF trial established feasibility and showed NT-proBNP reduction, improved health status, and favorable LV remodeling compared to enalapril 1. The TRANSITION trial demonstrated similar safety whether started before or after discharge 1.

Why This Matters

ARNI reduces cardiovascular death or HF hospitalization by 20% and all-cause mortality by 16% compared to enalapril 1. This represents a Class IA recommendation—the highest level of evidence and benefit 1. The evidence is so compelling that ARNI should replace ACE inhibitors or ARBs as the foundation of HFrEF treatment in NYHA Class II-III patients 1.

Common Pitfalls to Avoid

1. Forgetting the 36-hour washout: This causes angioedema risk and is the most dangerous error 2
2. Starting too conservatively in appropriate patients: Most stable patients on adequate ACE inhibitor/ARB doses should start at 49/51 mg, not 24/26 mg 2
3. Stopping at sub-target doses: Only 18% of usual care patients reach target dose versus 60.9% with pharmacist-led titration 4. Push to 97/103 mg twice daily unless truly not tolerated
4. Withholding due to asymptomatic hypotension: Focus on symptoms, not numbers alone
5. Not reducing diuretics proactively: In stable, non-congested patients, empirically lower loop diuretics to prevent hypotension 3