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1.5 Heart Failure: Classification, Staging & Guideline-Directed Medical Therapy
ABIM Internal Medicine Exam
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1 Chapter 0: The ABIM Exam, Blueprint & Study Strategy
0.1 Exam Format, Question Types & the 2026 Blueprint 0.2 Eligibility, Registration, Fees & Exam-Day Logistics 0.3 Scoring, the Passing Standard & Score Reports 0.4 Building a Blueprint-Weighted Study Plan
2 Chapter 1: Cardiovascular Disease (14% of Exam)
1.1 Ischemic Heart Disease & Acute Coronary Syndromes 1.2 Antithrombotic Therapy, Secondary Prevention & Mechanical Complications of MI 1.3 Atrial Fibrillation, Atrial Flutter & Stroke Prevention 1.4 Supraventricular Tachycardias, Ventricular Arrhythmias & Bradycardias 1.5 Heart Failure: Classification, Staging & Guideline-Directed Medical Therapy 1.6 Device Therapy, HFpEF & the Cardiomyopathies 1.7 Valvular Heart Disease & Endocarditis Prophylaxis 1.8 Pericardial Disease & Acute Aortic Syndromes 1.9 Hypertension: Classification, Diagnosis & Secondary Causes 1.10 Hypertensive Crises & Dyslipidemia 1.11 Adult Congenital Heart Disease & Coarctation of the Aorta 1.12 Syncope: Reflex, Orthostatic & Cardiac Causes 1.13 Cardiac Physical Examination, Murmurs & Antithrombotic Selection
3 Chapter 2: Endocrinology, Diabetes & Metabolism (9% of Exam)
2.1 Diabetes Mellitus: Diagnosis, Glycemic Targets & Pharmacotherapy 2.2 Insulin Therapy, Hyperglycemic Emergencies & Chronic Complications 2.3 Thyroid Function Testing & Hypothyroidism 2.4 Thyrotoxicosis, Thyroid Storm & Thyroid Nodules 2.5 Adrenal & Pituitary Disorders 2.6 Hypercalcemia, Hypocalcemia & Disorders of Mineral Metabolism 2.7 Osteoporosis & Paget Disease of Bone 2.8 Ovarian, Testicular & Reproductive Endocrine Disorders 2.9 Hypoglycemia, Endocrine Tumors, Polyglandular Syndromes & Severe Hypertriglyceridemia
4 Chapter 3: Gastroenterology & Hepatology (9% of Exam)
3.1 Esophageal Disease 3.2 Stomach & Duodenal Disease and Gastrointestinal Hemorrhage 3.3 Inflammatory Bowel Disease 3.4 Celiac Disease & Irritable Bowel Syndrome 3.5 Diverticular Disease & Colorectal Cancer Screening 3.6 Viral Hepatitis, Steatotic & Alcohol-Associated Liver Disease 3.7 Cirrhosis & the Complications of Portal Hypertension 3.8 Acute Pancreatitis 3.9 Chronic Pancreatitis & Biliary Tract Disease 3.10 Inherited, Autoimmune & Drug-Induced Liver Disease 3.11 Small Intestinal Disease, Ischemia & Gastrointestinal Complications of HIV
5 Chapter 4: Infectious Disease (9% of Exam)
4.1 Lower Respiratory Tract Infections & Sepsis Syndromes 4.2 Viral Respiratory Pathogens & Tuberculosis 4.3 Central Nervous System Infections 4.4 Skin, Soft Tissue, Bone & Joint Infections 4.5 Infective Endocarditis & Cardiovascular Infection 4.6 Clostridioides difficile & Catheter-Related Bloodstream Infection 4.7 HIV Diagnosis, Antiretroviral Therapy & Prevention 4.8 Opportunistic Infections & Sexually Transmitted Infections 4.9 Fever of Unknown Origin, Neutropenic Fever & Toxic Shock 4.10 Travel-Related Illness, Vector-Borne Disease & Outbreaks 4.11 Infection Prevention, Nosocomial Infection & Postexposure Prophylaxis 4.12 Rheumatic Fever, Poststreptococcal Disease, Enteric & Hepatic Infections
6 Chapter 5: Pulmonary Disease (9% of Exam)
5.1 COPD: Diagnosis, GOLD Classification & Initial Pharmacotherapy 5.2 Interventions That Reduce COPD Mortality & Exacerbation Management 5.3 Asthma: Diagnosis, Stepwise Therapy & Status Asthmaticus 5.4 Interstitial Lung Disease & Idiopathic Pulmonary Fibrosis 5.5 Sarcoidosis, Hypersensitivity Pneumonitis & Occupational Lung Disease 5.6 Pulmonary Embolism: Diagnosis, Risk Stratification & Anticoagulation 5.7 Pulmonary Hypertension & Sleep-Disordered Breathing 5.8 Acute Respiratory Distress Syndrome & Mechanical Ventilation 5.9 Pleural Disease, Empyema & Pneumothorax 5.10 Bronchiectasis, Cystic Fibrosis & Restrictive Lung Disease 5.11 Evaluation of Cough, Dyspnea, Hemoptysis & the Solitary Pulmonary Nodule
7 Chapter 6: Rheumatology & Orthopedics (9% of Exam)
6.1 Rheumatoid Arthritis: Diagnosis & Systemic Manifestations 6.2 Antirheumatic Pharmacotherapy & the Spondyloarthropathies 6.3 Gout: Pathophysiology & Acute Management 6.4 Urate-Lowering Therapy & Calcium Pyrophosphate Deposition Disease 6.5 Osteoarthritis 6.6 Systemic Lupus Erythematosus 6.7 Systemic Sclerosis, Sjogren Syndrome & Inflammatory Myopathies 6.8 The Vasculitides 6.9 Regional Musculoskeletal Syndromes, Back Pain & Sports Injuries 6.10 Other Primary Rheumatic Disorders & Mixed Connective Tissue Disease 6.11 Osteonecrosis & Metabolic Bone Disease
8 Chapter 7: Hematology (6% of Exam)
7.1 Approach to Anemia & the Microcytic Anemias 7.2 Macrocytic, Normocytic & Hemolytic Anemias 7.3 Hemoglobinopathies, Thalassemias & Paroxysmal Nocturnal Hemoglobinuria 7.4 Platelet Disorders, Thrombocytopenia & the Bleeding Patient 7.5 Coagulation Factor Disorders, Thrombophilia & Anticoagulant Reversal 7.6 Acute Leukemias, Chronic Leukemias & Myeloproliferative Neoplasms 7.7 Lymphomas & Plasma Cell Disorders 7.8 Myelodysplastic Syndrome, Myeloproliferative Neoplasms & Porphyria 7.9 Transfusion Medicine & Late Complications of Transplantation
9 Chapter 8: Medical Oncology (6% of Exam)
8.1 Breast, Lung, Colorectal & Prostate Cancer 8.2 Oncologic Emergencies 8.3 Genitourinary & Gynecologic Malignancies 8.4 Head and Neck, Bone & Soft Tissue Cancer and Cancer of Unknown Primary 8.5 Complications of Cancer & Its Treatment 8.6 Cancer Prevention, Survivorship & Psychosocial Care
10 Chapter 9: Nephrology & Urology (6% of Exam)
9.1 Acute Kidney Injury: Staging, Etiology & Urine Microscopy 9.2 Glomerular Disorders & Nephrotic Syndrome 9.3 Nephritic Syndromes, RPGN & Indications for Renal Replacement Therapy 9.4 Chronic Kidney Disease: Staging & Progression Retardation 9.5 Complications of Chronic Kidney Disease: Anemia, CKD-MBD & Acidosis 9.6 Hyponatremia, Hypernatremia & Water Balance 9.7 Potassium Disorders & Systematic Acid-Base Analysis 9.8 Renal Tubular Acidosis & Nephrolithiasis 9.9 Prostate Disorders, Urinary Incontinence & Other Urologic Conditions 9.10 Cystic Kidney Disease, Obstructive Uropathy, Tubulointerstitial Disease & Hematuria
11 Chapter 10: Neurology (4% of Exam)
10.1 Acute Ischemic Stroke: Syndromes & Reperfusion 10.2 Transient Ischemic Attack, Secondary Prevention & Hemorrhagic Stroke 10.3 Headache & Facial Pain 10.4 Seizures, Epilepsy & Movement Disorders 10.5 Multiple Sclerosis & Neuromuscular Junction Disorders 10.6 Motor Neuron Disease & Acute Peripheral Neuropathy 10.7 Cranial Neuropathies & Neuro-Ophthalmology 10.8 Peripheral Neuropathies, CNS Tumors & Other Neurologic Disorders
12 Chapter 11: Psychiatry & Behavioral Health (4% of Exam)
11.1 Major Depressive Disorder & Medical Mimics 11.2 Antidepressant Pharmacotherapy & Treatment-Resistant Depression 11.3 Bipolar Disorder, Mood Stabilizers & Lithium Toxicity 11.4 Anxiety, Stress-Related & Obsessive-Compulsive Disorders 11.5 Alcohol Use Disorder & Withdrawal 11.6 Pharmacotherapy for Alcohol & Opioid Use Disorder 11.7 Toxidromes, Psychiatric Emergencies & Suicide Risk Assessment 11.8 Psychotic, Somatic Symptom, Factitious & Personality Disorders 11.9 Eating Disorders, Sleep Disorders & Sexual Health
13 Chapter 12: Dermatology (3% of Exam)
12.1 Dermatitis, Papulosquamous & Inflammatory Dermatoses 12.2 Acne, Rosacea & Cutaneous Infections 12.3 Herpes Zoster & Autoimmune Blistering Diseases 12.4 Nodules, Tumors & Cutaneous Oncology 12.5 Dermatologic Emergencies & Severe Cutaneous Adverse Reactions 12.6 Pigment Disorders, Alopecia, Nail Disease & Photosensitivity 12.7 Vascular Dermatoses, Environmental Injury & Cutaneous Signs of Systemic Disease
14 Chapter 13: Obstetrics & Gynecology / Women's Health (3% of Exam)
13.1 Contraception, Preconception Care & Teratogenicity 13.2 Hypertensive Disorders of Pregnancy & Gestational Diabetes 13.3 Thyroid Disease & Venous Thromboembolism in Pregnancy 13.4 Menopause & Menopausal Hormone Therapy 13.5 Abnormal Uterine Bleeding, Endometrial Disease & Gynecologic Cancer Screening 13.6 Breast Disorders & Diseases of the Vulva and Vagina 13.7 Menstrual Disorders, Fibroids, Endometriosis & Early Pregnancy Complications
15 Chapter 14: Geriatric Syndromes (3% of Exam)
14.1 Comprehensive Geriatric Assessment & Frailty 14.2 Falls, Gait Assessment & Polypharmacy 14.3 Urinary Incontinence & Pressure Injuries in Older Adults 14.4 Mild Cognitive Impairment, Dementia & Its Subtypes 14.5 Delirium & the Pharmacotherapy of Cognitive Disorders 14.6 Palliative Care, Hospice & Advance Care Planning 14.7 Chronic Wounds, Nutrition, Swallowing, Constipation & Hip Fracture 14.8 Sensory Impairment, Dizziness, Elder Mistreatment & Care Settings
16 Chapter 15: Allergy & Immunology (2% of Exam)
15.1 Anaphylaxis: Recognition & Emergency Management 15.2 Urticaria & Angioedema 15.3 Drug Allergy, Desensitization & Adult Immunodeficiency 15.4 Food Allergy, Insect Venom Hypersensitivity, Serum Sickness & Contrast Reactions 15.5 Rhinitis, Conjunctivitis, Eosinophilic & Mast Cell Disorders
17 Chapter 16: Preventive Medicine, Immunization & Clinical Epidemiology
16.1 The USPSTF Framework & Evidence-Based Cancer Screening 16.2 Cardiovascular & Metabolic Screening and Primary Prevention 16.3 Adult Immunization & Vaccines in Special Populations 16.4 Clinical Epidemiology, Biostatistics & Study Design
18 Chapter 17: Miscellaneous - Ethics, Patient Safety & Quality Improvement (2% of Exam)
17.1 Principles of Bioethics & Decisional Capacity 17.2 Informed Consent, Treatment Refusal & Special Scenarios 17.3 Surrogate Decision-Making, Advance Directives & Confidentiality 17.4 Patient Safety Science, Medical Error & Diagnostic Reasoning 17.5 Quality Improvement Methods, Health Disparities & Health Equity
19 Chapter 18: Perioperative Medicine & Medical Consultation
18.1 Preoperative Cardiovascular Risk Assessment 18.2 Preoperative Pulmonary Risk & Perioperative Medication Management 18.3 Perioperative Anticoagulation, Bridging & Postoperative Complications
20 Chapter 19: Ophthalmology (1% of Exam)
19.1 The Acute Red Eye & Ophthalmic Emergencies 19.2 Painless Vision Loss & Chronic Ophthalmic Disease 19.3 Uveitis, Scleritis & Orbital Disease
21 Chapter 20: Otolaryngology & Dental Medicine (1% of Exam)
20.1 Dizziness, Vertigo & Epistaxis 20.2 Ear Disorders, Hearing Loss & Upper Respiratory Infections 20.3 Oral Cavity, Salivary Gland, Laryngeal & Taste and Smell Disorders
1.5 Heart Failure: Classification, Staging & Guideline-Directed Medical Therapy
Key Takeaways Explain This Topic AI
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.