1.5 Heart Failure: Classification, Staging & Guideline-Directed Medical Therapy
Key Takeaways
- Myocardial disease is a blueprint subsection that explicitly includes heart failure with preserved ejection fraction, myocarditis and the cardiomyopathies.
- Four foundational classes reduce mortality in heart failure with reduced ejection fraction: renin-angiotensin system inhibition, beta-blockade, mineralocorticoid receptor antagonism and SGLT2 inhibition.
- A 36-hour washout is required when switching from an ACE inhibitor to sacubitril/valsartan because of angioedema risk.
- Beta-blockade should be initiated when the patient is euvolemic, not during an acute decompensation.
- ACC/AHA stages describe risk and structural disease, whereas NYHA classes describe current symptom burden; a patient can move between NYHA classes without changing stage.
Last updated: August 2026
Heart failure (HF) affects over 6.5 million adults in the United States and accounts for substantial morbidity, mortality, and hospitalizations. The 2022 AHA/ACC/HFSA Guidelines established a unified classification system, defined the 4 foundational pillars of guideline-directed medical therapy (GDMT) for HFrEF, expanded SGLT2 inhibitor indications to preserved EF, and updated recommendations for cardiomyopathies and device therapy.
1. Classification & Staging of Heart Failure
Universal Ejection Fraction Phenotypes
- HFrEF (Heart Failure with reduced Ejection Fraction): LVEF <= 40%. Characterized by progressive left ventricular dilation, adverse eccentric remodeling, and marked neurohormonal activation.
- HFmrEF (Heart Failure with mildly reduced Ejection Fraction): LVEF 41% to 49%. Demonstrates intermediate biology; responds favorably to HFrEF GDMT.
- HFpEF (Heart Failure with preserved Ejection Fraction): LVEF >= 50%. Characterized by concentric remodeling, impaired active LV relaxation, increased passive myocardial stiffness, and elevated filling pressures.
- HFimpEF (Heart Failure with improved Ejection Fraction): Documented baseline LVEF <= 40% with a >=10-point increase and a second measurement of LVEF > 40%. Critical Rule: Never discontinue GDMT in patients whose EF improves to >40%, as cessation leads to rapid relapse of LV dysfunction and clinical heart failure (TRED-HF trial).
ACC/AHA Stages vs. NYHA Functional Classes
| Stage / Class | Definition | Clinical Description | Management Focus |
|---|---|---|---|
| Stage A | At Risk for Heart Failure | No structural heart disease or HF symptoms; risk factors present (HTN, DM, ASCVD, obesity, cardiotoxins) | Treat underlying risk factors (SGLT2i for DM/CKD, ACEi/ARB for HTN, statins) |
| Stage B | Pre-Heart Failure | Structural heart disease present (LVH, chamber enlargement, prior MI, LVEF <50%), elevated troponin/BNP, but NO symptoms | Initiate ACEi/ARB/ARNI and beta-blocker if LVEF <=40%; post-MI management |
| Stage C | Symptomatic Heart Failure | Structural heart disease with current or prior symptoms of HF | 4-Pillar GDMT, loop diuretics PRN, device therapy (ICD/CRT), cardiac rehab |
| Stage D | Advanced Heart Failure | Refractory HF symptoms interfering with daily life despite maximal GDMT; recurrent hospitalizations | Advanced therapies: Inotropes, Left Ventricular Assist Device (LVAD), Heart Transplant, Palliative Care |
| NYHA I | Class I | No limitation of physical activity; ordinary physical activity does not cause undue fatigue or dyspnea | Guideline medical management |
| NYHA II | Class II | Slight limitation of physical activity; comfortable at rest, but ordinary activity causes fatigue/palpitations/dyspnea | Guideline medical management |
| NYHA III | Class III | Marked limitation of physical activity; comfortable at rest, but less-than-ordinary activity causes symptoms | Guideline medical management + consideration of advanced add-ons |
| NYHA IV | Class IV | Unable to carry on any physical activity without discomfort; symptoms of HF present at rest | Advanced HF evaluation, continuous inotropes, mechanical support |
2. The 4 Pillars of GDMT for HFrEF
Every patient with HFrEF (LVEF <=40%, Stage C) should be initiated on all 4 foundational drug classes simultaneously at low doses and rapidly up-titrated every 1 to 2 weeks toward target doses:
Pillar 1: Angiotensin Receptor-Neprilysin Inhibitor (ARNI)
- First-line agent: Sacubitril/Valsartan (Entresto) (starting dose 24/26 mg or 49/51 mg PO BID, target 97/103 mg PO BID). Superior to ACE inhibitors in reducing CV death and HF hospitalizations by 20% (PARADIGM-HF trial).
- Alternative agents: ACE inhibitors (Enalapril 10-20 mg BID, Lisinopril 20-40 mg daily, Ramipril 10 mg daily) or ARBs (Valsartan 160 mg BID, Candesartan 32 mg daily) if ARNI is not accessible or tolerated.
- Mandatory 36-Hour Washout Period: When switching from an ACE inhibitor to an ARNI, a strict 36-hour washout period is required to allow complete clearance of ACE-induced bradykinin elevation and prevent severe, life-threatening angioedema. A washout period is not required when switching from an ARB to an ARNI.
Pillar 2: Evidence-Based Beta-Blockers
- Only 3 agents proven to reduce mortality:
- Carvedilol: non-selective beta-blocker with alpha-1 blocking vasodilating properties (starting 3.125 mg BID, target 25 mg BID [or 50 mg BID if weight >85 kg]).
- Metoprolol Succinate (Toprol-XL): beta-1 selective extended-release (starting 12.5-25 mg daily, target 200 mg daily). (Note: Metoprolol Tartrate does NOT have proven mortality benefit in HFrEF).
- Bisoprolol: beta-1 selective (starting 1.25 mg daily, target 10 mg daily).
- Initiation rule: Start only when the patient is clinically stable and euvolemic (compensated). Do not initiate during acute decompensated heart failure with volume overload, but do not stop pre-existing beta-blockers during mild-to-moderate decompensation unless cardiogenic shock or profound bradycardia is present.
Pillar 3: Mineralocorticoid Receptor Antagonists (MRA)
- Agents: Spironolactone (starting 12.5-25 mg daily, target 25-50 mg daily) or Eplerenone (starting 25 mg daily, target 50 mg daily; selective antagonist without antiandrogenic side effects like gynecomastia or mastodynia).
- Indications: NYHA Class II-IV with LVEF <=35%, or post-MI with LVEF <=40% and clinical HF or diabetes.
- Safety Thresholds: Baseline serum potassium must be <= 5.0 mEq/L and estimated GFR must be >= 30 mL/min/1.73m2 (or serum Cr <=2.5 mg/dL in men, <=2.0 mg/dL in women). Recheck basic metabolic panel at 1, 4, 8, and 12 weeks, then every 6 months.
Pillar 4: SGLT2 Inhibitors
- Agents: Dapagliflozin 10 mg daily (DAPA-HF) or Empagliflozin 10 mg daily (EMPEROR-Reduced).
- Key properties: Reduces CV mortality and HF hospitalizations by 25-30% regardless of the presence or absence of diabetes mellitus. Efficacy is maintained across the entire spectrum of ejection fraction (including HFmrEF and HFpEF via DELIVER and EMPEROR-Preserved). No dose titration required; eGFR cutoff is >=20 mL/min/1.73m2.
3. Additional GDMT Pharmacotherapies in HFrEF
| Drug / Class | Clinical Indication | Trial / Mechanism | Dosing & Clinical Pearls |
|---|---|---|---|
| Loop Diuretics (Furosemide, Bumetanide, Torsemide) | Fluid overload, peripheral edema, pulmonary congestion | Inhibits Na-K-2Cl cotransporter in thick ascending limb | Titrate to achieve euvolemia (dry weight). Relieves symptoms but does not reduce mortality alone. Furosemide PO:IV bioavailability is 2:1 (40 mg PO = 20 mg IV). Bumetanide 1 mg = Torsemide 20 mg = Furosemide 40 mg. |
| Hydralazine + Isosorbide Dinitrate (BiDil) | Self-identified Black patients with NYHA III-IV HFrEF on optimal GDMT; or patients intolerant to ARNI/ACEi/ARB due to renal failure/hyperkalemia | A-HeFT Trial: Hydralazine (antioxidant/arteriolar vasodilator) + ISDN (nitric oxide donor/venodilator) improves survival and reduces hospitalizations | Target dose: Hydralazine 75 mg TID + ISDN 40 mg TID (or fixed combination 37.5/20 mg TID up to 75/40 mg TID). Requires frequent dosing and compliance monitoring. |
| Ivabradine (Corlanor) | Symptomatic NYHA II-III HFrEF with LVEF <=35%, in normal sinus rhythm, with resting heart rate >= 70 bpm despite maximally tolerated beta-blocker dose | SHIFT Trial: Selectively inhibits the hyperpolarization-activated cyclic nucleotide-gated (I_f) funny current in the SA node, slowing HR without negative inotropy | Initial 5 mg PO BID, target 7.5 mg BID (adjust to resting HR 50-60 bpm). Contraindicated in atrial fibrillation, 2nd/3rd degree AV block, or acute decompensation. Side effect: luminous visual phenomena (phosphenes). |
| Vericiguat (Verquvo) | Symptomatic HFrEF (LVEF <45%) with recent worsening HF hospitalization or outpatient IV diuretic need | VICTORIA Trial: Directly stimulates soluble guanylate cyclase (sGC) to enhance cyclic GMP synthesis, restoring NO-sGC-cGMP signaling pathway | Initial 2.5 mg PO daily, titrated to 10 mg daily. Safe in advanced renal disease down to eGFR >=15 mL/min. |
| Digoxin | Persistent NYHA II-IV symptoms despite GDMT; or rate control in AFib with HFrEF | DIG Trial: Inhibits Na+/K+-ATPase, mild positive inotrope, vagomimetic | Reduces HF hospitalizations without mortality benefit. Maintain low serum trough level 0.5-0.9 ng/mL. Avoid >1.0 ng/mL (increased mortality). Watch for toxicity: arrhythmias, bidirectional VT, nausea, yellow-green halos (xanthopsia), especially in hypokalemia, hypomagnesemia, and renal failure. |
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Test Your Knowledge
A 54-year-old man with non-ischemic dilated cardiomyopathy and an LVEF of 28% presents for a routine follow-up. He has NYHA Class II symptoms on Lisinopril 20 mg daily, Metoprolol Succinate 100 mg daily, and Spironolactone 25 mg daily. His blood pressure is 126/78 mmHg, heart rate is 64 bpm, serum potassium is 4.6 mEq/L, and eGFR is 62 mL/min/1.73m2. You plan to switch Lisinopril to Sacubitril/Valsartan and add Dapagliflozin. What is the most critical instruction regarding the initiation of Sacubitril/Valsartan?
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