What are the indications, dosing, titration schedule, monitoring parameters, and contraindications for angiotensin‑converting enzyme (ACE) inhibitors?

ACE Inhibitors: Clinical Guide

ACE inhibitors should be prescribed to all patients with heart failure with reduced ejection fraction (HFrEF) and to patients with hypertension, post-myocardial infarction with left ventricular dysfunction, chronic kidney disease with proteinuria, or diabetes with hypertension, unless absolutely contraindicated. 1

Primary Indications

ACE inhibitors reduce mortality, hospitalizations, and improve quality of life in multiple cardiovascular conditions:

• Heart failure with reduced ejection fraction (HFrEF) - First-line therapy alongside beta-blockers for all NYHA classes 1
• Post-myocardial infarction - Especially with anterior MI, heart failure, or EF ≤40% (start within 24 hours) 2
• Hypertension - Particularly with diabetes, chronic kidney disease, or coronary artery disease 3, 4
• Chronic kidney disease - With proteinuria >500 mg/24h or albumin-to-creatinine ratio >30 mg/mmol 3
• Post-stroke/TIA - Preferably combined with diuretic after acute phase 3
• Left ventricular hypertrophy - To reduce cardiovascular events 3

Absolute Contraindications

Never prescribe ACE inhibitors if:

• History of angioedema (including with previous ACE inhibitor exposure) 1, 5
• Pregnancy or planning pregnancy 1
• Bilateral renal artery stenosis 1

Relative Contraindications (Use with Caution)

Seek specialist advice or use extreme caution when:

• Systolic blood pressure <80 mmHg 1
• Serum creatinine >3 mg/dL (>221 μmol/L) 1, 6
• Serum potassium >5.0 mEq/L 1, 6, 1
• Significant renal artery stenosis (unilateral) 7

Dosing and Titration

Starting Doses and Target Doses 1, 5

ACE Inhibitor	Starting Dose	Target/Maximum Dose
Captopril	6.25 mg three times daily	50 mg three times daily
Enalapril	2.5 mg twice daily	10-20 mg twice daily
Lisinopril	2.5-5 mg once daily	20-40 mg once daily
Ramipril	1.25-2.5 mg once daily	10 mg once daily
Fosinopril	5-10 mg once daily	40 mg once daily
Perindopril	2 mg once daily	8-16 mg once daily
Quinapril	5 mg twice daily	20 mg twice daily
Trandolapril	1 mg once daily	4 mg once daily

Titration Schedule

Start low and go slow, but aim high: 1, 6, 1

1. Begin with the lowest starting dose listed above
2. Double the dose every 2 weeks if well tolerated
3. Continue titrating until target dose achieved (the doses proven in clinical trials)
4. If target dose not tolerated, use the highest tolerated dose—intermediate doses still provide benefit, though slightly less than target doses 1
5. Never abruptly discontinue—can cause clinical deterioration 1

Critical point: In clinical trials, doses were increased to predetermined targets regardless of symptom response—this approach reduces mortality and hospitalizations 1

Monitoring Parameters

Baseline Assessment

• Serum creatinine and estimated GFR
• Serum potassium
• Blood pressure
• Volume status

Follow-up Monitoring 1, 6, 1

Check renal function and potassium:

• 1-2 weeks after initiation
• 1-2 weeks after each dose increase
• Periodically thereafter (every 3-6 months once stable)

Monitor more frequently in high-risk patients: 1

• Pre-existing hypotension
• Hyponatremia
• Diabetes mellitus
• Baseline azotemia
• Taking potassium supplements or aldosterone antagonists

Acceptable Changes After Starting ACE Inhibitor 6

Small increases are expected and acceptable:

• Creatinine increase <20%
• eGFR decrease <15%
• Potassium increase to <5.5 mEq/L (if asymptomatic)

Consider discontinuation if:

• Creatinine increases >20%
• eGFR decreases >15%
• Potassium >5.5 mEq/L despite management
• Symptomatic hypotension unresponsive to adjustments

Managing Adverse Effects

Hypotension 6

Asymptomatic low blood pressure requires no action. If symptomatic:

1. Reduce or eliminate other vasodilators (nitrates, calcium channel blockers)
2. If no signs of congestion, reduce diuretic dose
3. If these fail, seek specialist advice
4. Do not discontinue ACE inhibitor unless absolutely necessary

Cough 1, 5

• Occurs in 5-20% of patients (more common in certain populations, including up to 50% in Chinese patients) 5
• Dry, persistent, tickling sensation in throat
• First, exclude pulmonary congestion as cause 6, 5
• Most patients can continue therapy if cough is tolerable 5
• Only discontinue if cough is severe and prevents sleep 6
• If discontinuation necessary, substitute ARB (though some patients develop cough with ARBs too)

Angioedema 1, 5

• Occurs in <1% of patients (more frequent in Black patients) 1, 5
• Life-threatening—permanently discontinue ALL ACE inhibitors 1, 5
• ARBs may be considered as alternative, but use extreme caution—some patients develop angioedema with ARBs too 5

Hyperkalemia 6, 8

If potassium rises:

1. Discontinue potassium supplements
2. Reduce or stop potassium-sparing diuretics if safe
3. Ensure adequate diuretic therapy
4. Consider dietary potassium restriction
5. If persistent >5.5 mEq/L, may need to reduce ACE inhibitor dose or discontinue

Worsening Renal Function 6, 8

• Small increases in creatinine (up to 20%) are expected and acceptable
• Ensure patient is not volume depleted
• Check for bilateral renal artery stenosis if creatinine rises significantly
• May need dose reduction or discontinuation if creatinine increases >20% or eGFR decreases >15%

Important Clinical Pearls

All ACE inhibitors are equally effective for heart failure and survival—no evidence of superiority of one over another 1. Choose based on:

• Dosing convenience (once vs. multiple daily dosing)
• Cost
• Formulary availability

Combination therapy considerations:

• ACE inhibitor + beta-blocker: Recommended for HFrEF 1, 3, 4
• ACE inhibitor + diuretic: Appropriate for hypertension and heart failure 3
• ACE inhibitor + ARB: Not recommended routinely—increases adverse effects (hypotension, hyperkalemia, renal dysfunction) without clear mortality benefit 3, 5
• ACE inhibitor + ARB + aldosterone antagonist: Avoid—insufficient safety data, high risk of complications 5

Race-specific considerations: 9

• Black patients may have reduced blood pressure response to ACE inhibitor monotherapy
• However, ACE inhibitors remain appropriate when combined with calcium channel blocker or thiazide diuretic
• For heart failure, post-MI, and renal protection, ACE inhibitors are equally indicated regardless of race

Special populations:

• Diabetes with hypertension or CKD: ACE inhibitors are first-line 3, 4, 10
• Post-MI with LV dysfunction: Start within 24 hours unless contraindicated 2
• Elderly: Same indications apply; monitor closely for hypotension and renal function

If ACE inhibitor cannot be used: 3, 5, 4

1. First alternative: ARB (similar benefits for most indications)
2. Second alternative (if both contraindicated): Hydralazine + isosorbide dinitrate for heart failure 3, 4