1.3 Atrial Fibrillation, Atrial Flutter & Stroke Prevention

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

1.3 Atrial Fibrillation, Atrial Flutter & Stroke Prevention

Key Takeaways Explain This Topic AI

Dysrhythmias and conduction defects form a named blueprint subsection under Cardiovascular Disease.

CHA2DS2-VASc assigns two points each for age 75 or older and prior stroke or TIA, and one point each for heart failure, hypertension, age 65 to 74, diabetes and vascular disease.

Direct oral anticoagulants are preferred over warfarin except in mechanical valves and moderate-to-severe mitral stenosis.

Rate control and rhythm control produce similar mortality in most patients, so symptom burden rather than survival drives the choice.

Anticoagulation decisions in atrial flutter follow the same CHA2DS2-VASc rules as atrial fibrillation.

Last updated: August 2026

Cardiac arrhythmias and conduction disturbances span benign incidental findings to life-threatening emergencies. The ABIM exam emphasizes clinical recognition on 12-lead ECG, acute hemodynamic stabilization, stroke prevention in atrial fibrillation, antiarrhythmic drug selection tailored to underlying structural heart disease, and indications for pacing and defibrillation.

1. Atrial Fibrillation & Atrial Flutter

Atrial fibrillation (AF) is the most common sustained cardiac arrhythmia, characterized by disorganized, rapid atrial electrical activation (350-600 bpm) with an irregularly irregular ventricular response and loss of atrial mechanical contraction.

Acute Management: Hemodynamic Instability vs. Stability

Hemodynamically Unstable AF/Flutter: Immediate synchronized direct-current cardioversion (DCCV) (initial 120-200 J biphasic for AF; 50-100 J for flutter). Indications include hypotension/shock, acute pulmonary edema, ongoing myocardial ischemia, or acute altered mental status.

Hemodynamically Stable AF: Triage into rate control versus rhythm control and assess thromboembolic risk.

Rate Control vs. Rhythm Control

Evidence: The landmark AFFIRM and RACE trials demonstrated equivalent all-cause mortality and stroke rates between rate and rhythm control strategies. However, the EAST-AFNET 4 trial (2020) showed that early rhythm control (antiarrhythmic drugs or catheter ablation initiated within 1 year of AF diagnosis) significantly reduces cardiovascular death, stroke, and HF hospitalizations in patients with cardiovascular comorbidities.

Rate Control Targets: Resting heart rate <80 bpm for symptomatic patients (strict control) or <110 bpm for asymptomatic patients with preserved LV systolic function (lenient control via RACE II trial).

First-Line Rate Control Agents:

Beta-Blockers: Metoprolol Tartrate (2.5-5 mg IV q5min or 25-100 mg PO BID), Esmolol IV infusion, or Carvedilol (preferred in CAD/HFrEF).

Non-Dihydropyridine CCBs: Diltiazem (0.25 mg/kg IV bolus over 2 min, then 5-15 mg/h infusion, or 120-360 mg PO daily) or Verapamil. Strictly contraindicated in HFrEF (LVEF <=40%) due to potent negative inotropy precipitating pulmonary edema and cardiogenic shock.

Digoxin: Second-line add-on agent; particularly useful in sedentary patients with HFrEF. Ineffective for rate control during high sympathetic states (exercise, sepsis).

IV Amiodarone: Used for acute rate control in critically ill patients with severe hypotension, sepsis, or refractory HFrEF.

Antiarrhythmic Drug Selection for Rhythm Control

Antiarrhythmic selection depends strictly on the presence or absence of underlying structural heart disease (CAD, LVH, HFrEF):

Clinical Condition Recommended Antiarrhythmics Contraindicated Drugs & Rationale

No Structural Heart Disease (Normal LV, no CAD) Flecainide (50-150 mg PO BID); Propafenone (150-300 mg PO TID); Dronedarone (400 mg PO BID); Sotalol (80-160 mg PO BID) Amiodarone is relegated to second-line due to chronic extracardiac organ toxicities.

Coronary Artery Disease (CAD) / Prior MI Dofetilide (125-500 mcg PO BID); Dronedarone (400 mg PO BID); Sotalol (80-160 mg PO BID); Amiodarone (200 mg PO daily) Class IC agents (Flecainide, Propafenone) are STRICTLY CONTRAINDICATED due to increased lethal proarrhythmic mortality demonstrated in the CAST trial.

Heart Failure with Reduced EF (HFrEF <=40%) Amiodarone (200 mg PO daily); Dofetilide (requires inpatient telemetry initiation) Flecainide, Propafenone, Dronedarone, and Sotalol are CONTRAINDICATED. Dronedarone increases mortality in NYHA III-IV or decompensated HF (ANDROMEDA trial).

Pill-in-the-Pocket Approach: Outpatient self-administration of a single oral dose of Flecainide (200-300 mg) or Propafenone (450-600 mg) combined with a beta-blocker or diltiazem (given 30 min prior to prevent 1:1 atrial flutter conduction) for termination of paroxysmal AF in patients with structurally normal hearts once safety is confirmed in a monitored setting.

Amiodarone Extracardiac Toxicities & Monitoring

Pulmonary: Interstitial pneumonitis / pulmonary fibrosis (1-5%). Baseline chest radiograph and Pulmonary Function Tests (PFTs with DLCO); repeat for new respiratory symptoms or cough.

Thyroid: Amiodarone-induced hypothyroidism (AIH; Wolff-Chaikoff effect, treat with levothyroxine without stopping amiodarone) or Amiodarone-induced thyrotoxicosis (AIT Type 1: Jod-Basedow iodine excess; AIT Type 2: destructive thyroiditis). Check baseline TSH/free T4, then q6 months.

Hepatic: Elevated transaminases, cirrhosis. Monitor baseline LFTs, then q6 months.

Ophthalmic: Corneal microdeposits (benign, reversible) and optic neuropathy/neuritis (requires discontinuation).

Dermatologic: Photosensitivity and blue-gray skin discoloration (ceruloderma).

Electrophysiologic: Sinus bradycardia, QT prolongation (low torsades risk compared to other Class III agents), heart block.

Loading diagram... Atrial Fibrillation Management Algorithm: Hemodynamics, Rhythm Control, and Stroke Prophylaxis

2. Stroke Prevention & Anticoagulation in Atrial Fibrillation
The CHA2DS2-VASc Risk Score

Acronym Risk Factor Points Assigned
C C ongestive heart failure (or LVEF <=40%) +1
H H ypertension (or treated hypertension) +1
A2 A ge >= 75 years +2
D D iabetes mellitus +1
S2 S troke / TIA / Thromboembolism history +2
V V ascular disease (prior MI, PAD, complex aortic plaque) +1
A A ge 65 to 74 years +1
Sc S ex c ategory (Female) +1
Anticoagulation Decision Rules

Score >= 2 in Men or >= 3 in Women: Class I recommendation for long-term oral anticoagulation .

Score = 1 in Men or = 2 in Women: Class IIb recommendation; oral anticoagulation may be considered.

Score = 0 in Men or = 1 in Women: No antithrombotic therapy recommended (aspirin is ineffective for stroke prevention in AF and increases bleeding).

DOACs vs. Warfarin

Direct Oral Anticoagulants (DOACs) are preferred over Warfarin for non-valvular AF due to superior efficacy/safety, lower rates of intracranial hemorrhage, and no need for INR monitoring:

Apixaban (Eliquis): 5 mg PO BID. Reduce dose to 2.5 mg PO BID if patient has >=2 of the following: Age >=80 years, Body weight <=60 kg, or Serum Creatinine >=1.5 mg/dL.

Rivaroxaban (Xarelto): 20 mg PO daily with the evening meal (15 mg daily if CrCl 15-50 mL/min).

Dabigatran (Pradaxa): Direct thrombin inhibitor, 150 mg PO BID (75 mg BID if CrCl 15-30 mL/min).

Edoxaban (Savaysa): 60 mg PO daily (30 mg daily if CrCl 15-50 mL/min or weight <=60 kg; do not use if CrCl >95 mL/min due to increased renal clearance and reduced stroke efficacy).

Mandatory Warfarin (Target INR 2.0-3.0): DOACs are contraindicated in: (1) Moderate-to-severe rheumatic mitral stenosis ; and (2) Mechanical prosthetic heart valves (target INR 2.5-3.5 for mechanical mitral valves). Warfarin must be used in these settings.

HAS-BLED Score: Assesses 1-year major bleeding risk (Hypertension, Abnormal renal/liver function, Stroke, Bleeding history, Labile INR, Elderly >65y, Drugs/alcohol). A score >=3 identifies patients at high bleeding risk who need closer follow-up and modifiable risk factor correction—it is NOT a reason to withhold indicated anticoagulation.

Left Atrial Appendage Occlusion (LAAO / Watchman Device): Percutaneous option for patients with high stroke risk (CHA2DS2-VASc >=2) who have a formal contraindication to long-term oral anticoagulation (e.g., recurrent life-threatening unprovoked bleeding).