When should a patient with chronic kidney disease and congestive heart failure be treated with hydralazine and nitrates?

Hydralazine-Nitrate Therapy in CKD and Heart Failure

Hydralazine and isosorbide dinitrate should be used in patients with CKD and heart failure with reduced ejection fraction (HFrEF) primarily in two specific scenarios: (1) African American patients with NYHA class III-IV symptoms despite optimal medical therapy with ACEi/ARB, beta-blockers, and MRA, or (2) any patient who cannot tolerate first-line agents (ARNi, ACEi, or ARB) due to renal insufficiency or drug intolerance. 1

Primary Indication: African American Patients

The strongest evidence supports hydralazine-isosorbide dinitrate (H-ISDN) as add-on therapy for self-identified African American patients with symptomatic HFrEF (NYHA class III-IV) who remain symptomatic despite guideline-directed medical therapy 1. This is a Class 1, Level A recommendation with demonstrated:

• 43% relative risk reduction in all-cause mortality 2
• Number needed to treat of 21 over 12 months to prevent one death 2
• High economic value with cost per life-year <$60,000 1

The benefit was established in the A-HeFT trial, which showed remarkable improvements in survival and reduced HF hospitalizations 1.

Secondary Indication: ACEi/ARB/ARNi Intolerance

For patients of any race who cannot tolerate first-line neurohormonal blockade due to renal insufficiency, hypotension, or drug intolerance, H-ISDN might be considered as an alternative therapy 1. This is a Class 2b, Level C-LD recommendation, meaning the evidence is weaker but the option exists when standard therapy is impossible.

Why This Matters in CKD

The 2022 ACC/AHA/HFSA guidelines specifically acknowledge that renal insufficiency is a common reason patients cannot tolerate ACEi/ARB 1. The FDA label notes that hydralazine can maintain or even improve renal blood flow and glomerular filtration rate in hypertensive patients 3. However, the label also cautions to use hydralazine carefully in advanced renal damage 3.

Recent observational data from dialysis patients showed H-ISDN was associated with lower all-cause mortality (HR 0.48) and cardiovascular death (HR 0.62), though HF hospitalizations were paradoxically higher 4. This suggests potential benefit even in end-stage kidney disease, though this requires careful interpretation.

Critical Implementation Details

Dosing Requirements

The clinical trial benefits were achieved only with high doses that are often higher than used in routine practice 1:

• Target doses from trials must be achieved for mortality benefit
• Uptitration should be aggressive as tolerated
• Short-acting nitrate formulations were used in successful trials

Common Pitfalls to Avoid

1. Inadequate dosing: Most patients in practice receive lower doses than those proven effective in trials 1

2. Poor adherence: Real-world data shows very low prescription refill rates and high discontinuation (27% in one study) 1, 5, 6

3. Adverse effects limiting use:

   • Headaches, dizziness, and hypotension are common 3, 5
   • Drug-induced lupus syndrome can occur (monitor ANA titers) 3
   • Peripheral neuritis may develop (consider pyridoxine supplementation) 3

4. Using as monotherapy: The combination is essential; neither agent alone shows clear mortality benefit 7

5. Expecting benefit in non-African Americans on standard therapy: Evidence for benefit as add-on therapy in non-African Americans is lacking 1

When NOT to Use

• Do not use H-ISDN as first-line therapy in any patient when ARNi, ACEi, or ARB can be tolerated 1
• Insufficient data exists for concomitant use with ARNi 1
• Caution in coronary artery disease: Hydralazine can precipitate angina and myocardial ischemia through myocardial stimulation 3
• Avoid in mitral valve disease: May increase pulmonary artery pressure 3

Clinical Algorithm

Step 1: Determine if patient has HFrEF (LVEF ≤40%)

Step 2: Assess race/ethnicity

• If African American with NYHA III-IV symptoms on ACEi/ARB + beta-blocker + MRA → ADD H-ISDN (strong recommendation) 1

Step 3: If not African American or not on optimal therapy, assess tolerance to first-line agents

• If intolerant to ARNi/ACEi/ARB due to renal insufficiency or other contraindication → CONSIDER H-ISDN as alternative (weak recommendation, refer to HF specialist) 1
• If tolerating first-line agents → Do not add H-ISDN

Step 4: If initiating H-ISDN

• Start low, uptitrate to trial-proven target doses
• Monitor for hypotension, headache, lupus-like symptoms
• Check CBC and ANA periodically 3
• Consider pyridoxine supplementation 3
• Ensure close follow-up for adherence

Nuance Regarding CKD Specifically

The guidelines explicitly mention that renal insufficiency is a valid reason to consider H-ISDN when ACEi/ARB cannot be used 1. The FDA label indicates hydralazine can maintain renal function, but caution is needed in advanced renal disease 3. The recent dialysis study suggests potential benefit even in ESKD 4, though this requires prospective validation. When CKD prevents use of standard neurohormonal blockade, H-ISDN becomes a reasonable alternative regardless of race, though referral to a HF specialist is recommended 1.