14.1 Acute Coronary Syndromes & Myocardial Infarction

ABFM Family Medicine Certification Study Guide Exam

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1 Chapter 1: Exam Structure, Blueprint & Clinical Decision-Making

1.1 Exam Blueprint, FMCLA vs. One-Day Exam & Board Scoring 1.2 Clinical Reasoning, Test-Taking Strategy & Ambiguity Management 1.3 Evidence-Based Medicine & Clinical Practice Guidelines in Primary Care

2 Chapter 2: Healthcare Systems, Practice Management & Quality

2.1 Practice Management, Billing, Coding & Documentation 2.2 Quality Improvement, Patient Safety & Diagnostic Stewardship 2.3 Interprofessional Team-Based Care & Care Coordination

3 Chapter 3: Ethics, Law, Biostatistics & Health Equity

3.1 Medical Ethics, Informed Consent & Surrogate Decision-Making 3.2 Biostatistics, Clinical Epidemiology & Diagnostic Test Interpretation 3.3 Social Determinants of Health, Health Equity & Cultural Humility 3.4 Physician Wellness, Burnout Prevention & Professionalism

4 Chapter 4: Lifestyle Counseling & Behavior Change

4.1 Alcohol Use Screening & Brief Intervention 4.2 Illicit Drug & Cannabis Counseling 4.3 Tobacco & Vaping Cessation Counseling

5 Chapter 5: Nutrition, Physical Activity & Chronic Disease Prevention

5.1 Dietary Counseling for Obesity & Chronic Disease Prevention 5.2 Exercise Prescription & Physical Activity Counseling 5.3 Genetic Risk Assessment & Family History Counseling

6 Chapter 6: Routine Adult Immunizations

6.1 ACIP Adult Respiratory Vaccines: Influenza, COVID-19, RSV & Pneumococcal 6.2 ACIP Adult Non-Respiratory Vaccines: Tdap, Shingrix, HPV & Hep B 6.3 Immunizations in Special Populations: Pregnancy, Asplenia & Immunocompromise

7 Chapter 7: Pediatric Health Maintenance & Surveillance

7.1 Newborn Examination & Early Postnatal Care 7.2 Well-Child Care, Developmental Surveillance & Milestones 7.3 Pediatric & Adolescent Screening: Vision, Hearing, Anemia & Lead 7.4 Pediatric Oral Health, Dental Screening & Fluoride

8 Chapter 8: Behavioral Health & Safety Screening

8.1 Primary Care Depression, Anxiety & Behavioral Health Screening 8.2 Domestic Violence, Intimate Partner Violence & Firearm Safety 8.3 Occupational Health & Recreational Safety Counseling

9 Chapter 9: Adult Preventive Screening: Cardiovascular & Metabolic

9.1 Cardiovascular Disease & Hypertension Screening 9.2 Type 2 Diabetes Screening & Prediabetes Risk Stratification 9.3 Abdominal Aortic Aneurysm & Osteoporosis Screening

10 Chapter 10: Adult Cancer Screening: Breast & Gynecologic

10.1 Breast Cancer Screening & Risk-Assessment 10.2 Cervical Cancer Screening & ASCCP Algorithms 10.3 Skin Cancer Clinical Assessment & Counseling

11 Chapter 11: Adult Cancer Screening: Colorectal, Lung & Prostate

11.1 Colorectal Cancer Screening Modalities & Intervals 11.2 Lung Cancer Screening with Low-Dose CT 11.3 Prostate Cancer Screening & Shared Decision-Making

12 Chapter 12: Sexual Health, Infectious Disease Screening & Contraception

12.1 Sexual Health Counseling & Risk-Reduction Strategies 12.2 STI Screening: Chlamydia, Gonorrhea, Syphilis & Trichomoniasis 12.3 Bloodborne Infectious Disease Screening: HIV & Hepatitis C

13 Chapter 13: Reproductive Life Planning, Lactation & Preoperative Care

13.1 Preconception Planning & Comprehensive Contraception Management 13.2 Lactation Support & Breastfeeding Counseling 13.3 Preoperative Medical Evaluation & Pre-Participation Sports Exam

14 Chapter 14: Emergent Cardiovascular Conditions

14.1 Acute Coronary Syndromes & Myocardial Infarction 14.2 Acute Chest Pain Risk Stratification & Triage 14.3 Acute or Critical Valvular Heart Emergencies

15 Chapter 15: Cardiac Arrhythmias, Heart Failure & Hypertensive Crises

15.1 Acute Atrial & Ventricular Arrhythmias 15.2 Acute Decompensated Heart Failure & Cardiogenic Shock 15.3 Hypertensive Emergency & Urgency Management

16 Chapter 16: Vascular & Thromboembolic Emergencies

16.1 Pulmonary Embolism & Deep Vein Thrombosis 16.2 Acute Aortic Syndromes & Peripheral Vascular Emergencies 16.3 Critical Limb Ischemia & Acute Arterial Occlusion

17 Chapter 17: Neurologic Emergencies: Stroke & Altered Consciousness

17.1 Acute Ischemic Stroke & Intracranial Hemorrhage 17.2 Syncope Evaluation & Status Epilepticus 17.3 Acute Delirium, Encephalopathy & Severe Confusion

18 Chapter 18: Neurologic Trauma & Acute Cranial Emergencies

18.1 Concussion, Moderate-to-Severe TBI & Intracranial Injury 18.2 Thunderclap & Acute Severe Secondary Headaches 18.3 Acute Ophthalmologic Emergencies

19 Chapter 19: Acute Abdominal, Pelvic & Gastrointestinal Emergencies

19.1 Acute Abdominal & Pelvic Pain Triage 19.2 Upper & Lower Gastrointestinal Bleeding 19.3 Acute Hepatic Failure, Cholangitis & Severe Jaundice

20 Chapter 20: Acute Pulmonary & Airway Emergencies

20.1 Acute Hypoxic Respiratory Failure & ARDS 20.2 Severe Community-Acquired Pneumonia & Empyema 20.3 Acute Severe Epistaxis & Airway Obstruction

21 Chapter 21: Acute Traumatic Injuries & Wound Care

21.1 Major Trauma Resuscitation & Initial Assessment 21.2 Burn Assessment, Inhalation Injury & Resuscitation 21.3 Laceration Management, Complex Wounds & Animal Bites

22 Chapter 22: Acute Orthopedic & Musculoskeletal Emergencies

22.1 Acute Ambulatory Fractures & Initial Splinting 22.2 Compartment Syndrome & Major Orthopedic Trauma 22.3 Septic Arthritis & Acute Microcrystalline Crises

23 Chapter 23: Severe Infections, Sepsis & Systemic Emergencies

23.1 Sepsis, Septic Shock & Initial Fluid Resuscitation 23.2 Necrotizing Soft Tissue Infections & Severe CNS Infections 23.3 Anaphylaxis Diagnosis, Epinephrine Dosing & Airway Protection

24 Chapter 24: Metabolic, Endocrine & Electrolyte Emergencies

24.1 Diabetic Ketoacidosis & Hyperosmolar Hyperglycemic State 24.2 Critical Electrolyte Emergencies: Dyskalemias & Dysnatremias 24.3 Severe Calcium Abnormalities & Acute Adrenal Crisis

25 Chapter 25: Hematologic, Urologic & Dental Emergencies

25.1 Severe Symptomatic Anemias & Coagulopathic Emergencies 25.2 Testicular Torsion, Priapism & Acute Urinary Retention 25.3 Urgent Odontogenic Infections & Dental Trauma

26 Chapter 26: Psychiatric, Behavioral & Obstetric/Gynecologic Emergencies

26.1 Suicidal Ideation, Acute Agitation & Behavioral Emergencies 26.2 Acute Physical & Sexual Assault Care 26.3 Life-Threatening Vaginal Bleeding & Ectopic Pregnancy 26.4 Environmental Heat Stroke & Severe Hypothermia

27 Chapter 27: Acute Head, Neck & Neurologic Symptoms

27.1 Primary Acute Headaches: Migraine, Tension & Cluster 27.2 Concussion & Minor Closed Head Injury Evaluation 27.3 Transient Ischemic Attack Evaluation & ABCD2 Risk Scoring

28 Chapter 28: Acute Cranial Nerves, Hearing & Sensory Symptoms

28.1 Peripheral Neuropathies: Bell's Palsy, Carpal Tunnel & Radiculopathy 28.2 Acute Tinnitus, Sudden Sensorineural Hearing Loss & Cerumen Impaction 28.3 Acute Dizziness, Benign Paroxysmal Positional Vertigo & Vestibular Neuritis

29 Chapter 29: Acute Upper Respiratory Tract Infections

29.1 Acute Viral Rhinosinusitis vs. Bacterial Rhinosinusitis 29.2 Acute Pharyngitis: Group A Streptococcus & Centor Criteria 29.3 Acute Otitis Media, Otitis Externa & Serous Effusion

30 Chapter 30: Acute Lower Respiratory Infections & Cough

30.1 Influenza, COVID-19 & Viral Respiratory Syndromes 30.2 Acute Bronchitis & Lower Respiratory Tract Infections 30.3 Ambulatory Community-Acquired Pneumonia

31 Chapter 31: Allergic, Nasal & Non-Infectious Pulmonary Conditions

31.1 Allergic Rhinitis & Acute Non-Anaphylactic Allergic Reactions 31.2 Acute Dyspnea in Ambulatory Care 31.3 Interstitial Lung Diseases & Sarcoidosis Presentation

32 Chapter 32: Acute Chest, Cardiac & Vascular Symptoms

32.1 Palpitations Evaluation & Arrhythmia Triage in Primary Care 32.2 Deep Vein Thrombosis & Superficial Thrombophlebitis 32.3 Ambulatory Hypotension & Orthostasis Evaluation

33 Chapter 33: Acute Upper Gastrointestinal Conditions

33.1 Peptic Ulcer Disease & Gastritis 33.2 Dysphagia, Esophagitis & Acute Esophageal Disorders 33.3 Acute Nausea, Vomiting & Foodborne Illness

34 Chapter 34: Acute Lower Gastrointestinal Conditions

34.1 Acute Infectious Diarrhea & Gastroenteritis 34.2 Acute Constipation & Functional Bowel Changes 34.3 Ano-Rectal Disorders: Hemorrhoids, Fissures, Abscesses & Pruritus Ani

35 Chapter 35: Inflammatory, Functional & Malabsorptive GI Disorders

35.1 Acute Flares of Inflammatory Bowel Disease 35.2 Irritable Bowel Syndrome: Diagnosis, Subtyping & Management 35.3 Celiac Disease & Malabsorption Syndromes

36 Chapter 36: Acute Abdominal, Hepatic & Biliary Disorders

36.1 Ambulatory Abdominal & Pelvic Pain Triage 36.2 Acute Cholecystitis, Biliary Colic & Pancreatitis 36.3 Acute Liver Injury & Viral Hepatitis

37 Chapter 37: Acute Abdominal Wall, Hernias & Dental Conditions

37.1 Abdominal Wall, Inguinal & Ventral Hernias 37.2 Acute Dental Pain, Odontogenic Abscess & Aphthous Ulcers 37.3 Acute Edema: Unilateral vs. Bilateral Diagnostic Evaluation

38 Chapter 38: Acute Infectious Dermatoses

38.1 Bacterial Skin Infections: Impetigo, Cellulitis & Cutaneous Abscesses 38.2 Fungal Skin Infections: Tinea Corporis, Cruris, Pedis & Onychomycosis 38.3 Viral Cutaneous Infections: Herpes Simplex, Zoster & Molluscum Contagiosum

39 Chapter 39: Inflammatory, Allergic & Autoimmune Dermatoses

39.1 Atopic Dermatitis, Contact Dermatitis & Eczematous Flares 39.2 Non-Infectious Rashes: Urticaria, Drug Eruptions & Erythema Multiforme 39.3 Cutaneous Malignancies & Premalignant Lesions: AK, BCC, SCC & Melanoma

40 Chapter 40: Acute Shoulder, Elbow & Upper Extremity Injuries

40.1 Rotator Cuff Pathology, Tendinopathy & Shoulder Impingement 40.2 Lateral & Medial Epicondylitis, Olecranon Bursitis & Elbow Sprains 40.3 Wrist & Hand Soft-Tissue Injuries: De Quervain, TFCC & Finger Sprains

41 Chapter 41: Acute Knee, Ankle & Lower Extremity Injuries

41.1 Meniscal Tears, Ligamentous Knee Injuries & Patellofemoral Pain 41.2 Ankle Sprains, Ottawa Ankle Rules & Achilles Tendinopathy 41.3 Plantar Fasciitis, Shin Splints & Overuse Syndromes

42 Chapter 42: Acute Ambulatory Fractures & Dislocations

42.1 Distal Radius, Scaphoid & Common Upper Extremity Fractures 42.2 Metatarsal, Clavicle & Common Lower Extremity Fractures 42.3 Joint Dislocation Management: Nursemaid's Elbow & Shoulder Subluxation

43 Chapter 43: Acute Axial Musculoskeletal Pain & Falls

43.1 Acute Low Back Pain: Red Flags, Strain & Disc Herniation 43.2 Acute Cervical Strain, Whiplash & Axial Neck Pain 43.3 Evaluation of Falls in Ambulatory & Older Patients

44 Chapter 44: Acute Inflammatory Arthropathies & Generalized Pain

44.1 Acute Inflammatory Arthritis & Spondyloarthropathies 44.2 Myalgias, Rhabdomyolysis & Post-Viral Pain Syndromes 44.3 Acute Non-Headache Pain Management Strategies

45 Chapter 45: Acute Renal, Urinary & Genitourinary Conditions

45.1 Uncomplicated UTI, Pyelonephritis & Acute Urethritis 45.2 Hematuria Workup & Glomerulonephritis 45.3 Nephrolithiasis & Acute Urinary Tract Obstruction

46 Chapter 46: Acute Male Genitourinary & Prostatic Conditions

46.1 Acute Prostatitis, Epididymitis & Orchitis 46.2 Acute Scrotal Pain: Torsion vs Appendage, BPH & Male Genital Emergencies 46.3 Acute Urinary Retention & Incontinence Evaluation

47 Chapter 47: Acute Women's Health & Early Pregnancy Care

47.1 Early Pregnancy Diagnosis, Dating & Initial Complications 47.2 Abnormal Uterine Bleeding & Acute Menstrual Disorders 47.3 Premenstrual Syndrome & Premenstrual Dysphoric Disorder

48 Chapter 48: Breast Disorders, STIs & Pediatric Elimination

48.1 Palpable Breast Mass, Mastitis & Nipple Discharge 48.2 Sexually Transmitted Infections: Diagnosis, Staging & CDC Guidelines 48.3 Pediatric Enuresis & Encopresis

49 Chapter 49: Systemic Signs, Metabolic Dysregulation & Miscellaneous Infections

49.1 Acute Fever, Sepsis Screening & FUO in Primary Care 49.2 Acute Hyperglycemia & Symptomatic Hypoglycemia 49.3 Electrolyte Abnormalities: Mild-to-Moderate Disturbances 49.4 Vector-Borne, Tick-Borne & Rickettsial Illnesses

50 Chapter 50: Chronic Cardiovascular Diseases: Hypertension & Ischemia

50.1 Essential Hypertension Management: 2025 AHA/ACC Guideline & JNC Strategies 50.2 Chronic Coronary Artery Disease & Post-MI Secondary Prevention 50.3 Chronic Heart Failure: HFrEF, HFpEF & Quadruple GDMT

51 Chapter 51: Chronic Vascular, Valvular & Dyslipidemic Diseases

51.1 Peripheral Arterial Disease & Claudication 51.2 Chronic Valvular Heart Disease & Murmur Evaluation 51.3 Lipid Disorders & ASCVD Risk-Based Statin Therapy

52 Chapter 52: Chronic Respiratory Diseases: Asthma & COPD

52.1 Chronic Asthma Management: GINA Stepwise SMART Therapy 52.2 Chronic Obstructive Pulmonary Disease: GOLD Recommendations 52.3 Solitary Pulmonary Nodule Evaluation & Fleischner Society Criteria

53 Chapter 53: Chronic Metabolic Diseases: Diabetes Mellitus

53.1 Type 2 Diabetes Management: ADA Pharmacotherapy Algorithms 53.2 Type 1 Diabetes: Basal-Bolus Insulin, CGMs & Diabetic Complications 53.3 Diabetic Microvascular & Macrovascular Disease Surveillance

54 Chapter 54: Obesity, Nutrition & Metabolic Bone Diseases

54.1 Medical & Behavioral Management of Obesity & Incretin Mimetics 54.2 Osteoporosis & Metabolic Bone Disease: DEXA, FRAX & Antiresorptives 54.3 Nutritional Deficiencies: Vitamin D, B12, Iron & Malnutrition

55 Chapter 55: Chronic Endocrine Disorders

55.1 Primary & Subclinical Hypothyroidism, Hyperthyroidism & Nodules 55.2 Adrenal Disorders: Addison's Disease & Cushing's Syndrome 55.3 Hypercalcemia, Hyperparathyroidism & Pituitary Disorders

56 Chapter 56: Chronic Kidney Disease & Venous Disorders

56.1 Chronic Kidney Disease: KDIGO Staging & Renoprotective Therapy 56.2 Chronic Venous Insufficiency, Stasis Dermatitis & Lymphedema 56.3 Chronic Electrolyte & Acid-Base Management in CKD

57 Chapter 57: Chronic Gastrointestinal & Hepatic Diseases

57.1 Gastroesophageal Reflux Disease, Barrett's Esophagus & Dyspepsia 57.2 Chronic Liver Disease: MASLD/NAFLD, Cirrhosis & Portal Hypertension 57.3 Viral Hepatitis B & C: Long-Term Monitoring & DAA Therapy

58 Chapter 58: Colorectal Surveillance & Chronic Pancreaticobiliary Care

58.1 Post-Polypectomy Colorectal Polyp Surveillance Guidelines 58.2 Chronic Pancreatitis & Exocrine Pancreatic Insufficiency 58.3 Chronic Nausea, Gastroparesis & Functional GI Disorders

59 Chapter 59: Chronic Musculoskeletal & Rheumatologic Disorders

59.1 Osteoarthritis: Hip, Knee & Hand Management 59.2 Spinal Conditions: Spinal Stenosis, Spondylolisthesis & Compression Fractures 59.3 Chronic Myopathies & Fibromyalgia Syndrome

60 Chapter 60: Chronic Neurologic & Neurodegenerative Disorders

60.1 Dementia: Alzheimer's, Vascular & Lewy Body Disease 60.2 Parkinson's Disease & Essential Tremor 60.3 Epilepsy: Chronic Antiseizure Medications & Post-Stroke Care

61 Chapter 61: Chronic Peripheral Nerves, Pain & Sensory Disorders

61.1 Diabetic & Chronic Peripheral Neuropathies 61.2 Chronic Pain Syndromes & Chronic Daily Headaches 61.3 Chronic Tinnitus, Presbycusis & Persistent Dizziness

62 Chapter 62: Chronic Psychiatric Disorders

62.1 Major Depressive Disorder & Generalized Anxiety Disorder 62.2 Bipolar Disorder: Maintenance Pharmacotherapy & Lithium Monitoring 62.3 Adult & Pediatric Attention-Deficit/Hyperactivity Disorder

63 Chapter 63: Chronic Behavioral Health & Neurodevelopmental Conditions

63.1 Chronic Behavioral Conditions: PTSD, OCD & Somatization 63.2 Autism Spectrum Disorder & Intellectual Disabilities 63.3 Eating Disorders: Anorexia Nervosa, Bulimia & Binge Eating

64 Chapter 64: Chronic Substance Use Disorders & Tobacco Cessation

64.1 Alcohol Use Disorder: Pharmacotherapy & Relapse Prevention 64.2 Opioid & Stimulant Use Disorders: MOUD & Harm Reduction 64.3 Longitudinal Tobacco Cessation Pharmacotherapy

65 Chapter 65: Chronic Dermatologic Conditions

65.1 Acne Vulgaris, Rosacea & Seborrheic Dermatitis 65.2 Chronic Plaque Psoriasis & Biologic Therapies 65.3 Chronic Eczema, Hidradenitis Suppurativa & Cutaneous Lupus

66 Chapter 66: Chronic Reproductive, Infectious & Geriatric Special Care

66.1 Chronic Menstrual Disorders, Infertility & Sexual Dysfunction 66.2 Menopause Management & Hormone Replacement Therapy 66.3 Chronic HIV Infection Management & Primary Care Integration 66.4 Gender-Affirming Primary Care & Hormone Therapy 66.5 Advance Care Planning, Palliative Care & End-of-Life Symptom Control

67 Chapter 67: Continuity Care: Sleep, Fatigue, Cancer, Pregnancy & the Adult Preventive Visit

67.1 Chronic Insomnia & Obstructive Sleep Apnea 67.2 Chronic Malaise, Fatigue & ME/CFS 67.3 Primary Care During Cancer Treatment & Survivorship 67.4 Routine Prenatal Care & Longitudinal Pregnancy Management 67.5 The Periodic Adult Health Examination & Medicare Annual Wellness Visit

14.1 Acute Coronary Syndromes & Myocardial Infarction

Key Takeaways Explain This Topic AI

ECG diagnostic criteria for STEMI require >=1.0 mm (0.1 mV) of ST elevation in >=2 contiguous leads, except leads V2-V3 which mandate age- and sex-specific thresholds: >=1.5 mm in women of any age, >=2.0 mm in men >=40 years, and >=2.5 mm in men <40 years; modified Sgarbossa criteria identify STEMI equivalents in left bundle branch block (LBBB) or ventricular pacing.

Posterior STEMI presents with horizontal ST depression, tall broad R waves (R/S ratio > 1), and upright T waves in leads V1-V3, confirmed by >=0.5 mm ST elevation in posterior leads V7-V9; right ventricular MI (proximal RCA occlusion) shows ST elevation in lead III > II and >=1.0 mm ST elevation in right-sided lead V4R, requiring aggressive preload maintenance with IV isotonic fluids and strict avoidance of nitrates, diuretics, and opioids.

High-sensitivity cardiac troponin (hs-cTn) rapid protocols (0/1-hour and 0/2-hour) leverage baseline concentrations and absolute dynamic deltas to achieve a negative predictive value >99% for acute myocardial infarction rule-out while identifying acute injury candidates for expedited invasive management.

Immediate pharmacotherapy includes non-enteric chewed aspirin 162-325 mg, potent P2Y12 inhibitor loading (ticagrelor 180 mg or prasugrel 60 mg preferred over clopidogrel 600 mg in primary PCI), parenteral anticoagulation (unfractionated heparin or enoxaparin), high-intensity statin (atorvastatin 80 mg), and oral beta-blockers within 24 hours (withheld in decompensated heart failure, cardiogenic shock risk, bradycardia, PR interval >0.24 s, or cocaine use).

Reperfusion benchmarks dictate primary percutaneous coronary intervention (PCI) with a door-to-balloon time <=90 minutes at PCI-capable centers (or first medical contact to device <=120 minutes if transferred); fibrinolysis (tenecteplase) door-to-needle time <=30 minutes is indicated only when PCI transfer delay exceeds 120 minutes and absolute contraindications are absent.

Last updated: September 2026

Spectrum of Acute Coronary Syndromes (ACS)

Acute coronary syndromes encompass a clinical and pathophysiological continuum triggered by an abrupt, critical imbalance between myocardial oxygen demand and coronary blood supply. In the overwhelming majority of cases, ACS is initiated by the rupture or erosion of a vulnerable atherosclerotic plaque within an epicardial coronary artery.

Pathophysiologic Cascade

Plaque Disruption : Fibrous cap rupture (most common, driven by macrophage matrix metalloproteinases) or superficial endothelial plaque erosion exposes underlying thrombogenic collagen and subendothelial tissue factor to circulating blood.

Platelet Adhesion & Activation : Platelets adhere to exposed von Willebrand factor via glycoprotein Ib (GPIb) surface receptors. Platelet activation ensues, causing the degranulation and release of adenosine diphosphate (ADP), thromboxane A2 (TxA2), and serotonin, alongside surface expression of active glycoprotein IIb/IIIa (GPIIb/IIIa) receptors.

Thrombus Propagation : Conformational activation of GPIIb/IIIa receptors binds circulating fibrinogen, cross-linking adjacent platelets to form a primary platelet plug. Concurrently, the coagulation cascade is triggered by tissue factor, generating thrombin, which converts soluble fibrinogen into an insoluble fibrin meshwork, stabilizing the intra-luminal thrombus. ACUTE CORONARY SYNDROMES SPECTRUM

• ┌────────────────────────────────────────────────────────────────────────────────────────┐
• │ VULNERABLE PLAQUE DISRUPTION │
• │ (Rupture or Erosion + Platelet Activation) │
• └───────────────────────────────────────────┬────────────────────────────────────────────┘
• │
• ┌────────────────────────────────┴────────────────────────────────┐
• ▼ ▼
• ┌─────────────────────────────────────────┐ ┌─────────────────────────────────────────┐
• │ TOTAL OCCLUSIVE THROMBUS │ │ SUB-TOTAL / INTERMITTENT OCCLUSION │
• │ • Fibrin- and red-cell-rich "red" clot │ │ • Platelet-rich "white" clot │
• │ • Transmural myocardial ischemia │ │ • Subendocardial myocardial ischemia │
• │ • Persistent ST elevation on 12-lead │ │ • ST depression, T inversion, or normal │
• │ • Troponin positive (extensive injury) │ │ • Troponin positive vs. negative │
• └────────────────────┬────────────────────┘ └────────────────────┬────────────────────┘
• │ │
• ▼ ▼
• ┌─────────────────────────────────────────┐ ┌─────────────────────────────────────────┐
• │ STEMI (ST-Elevation MI) │ │ NSTE-ACS (Non-ST-Elevation ACS) │
• │ • Immediate emergency reperfusion │ │ • Troponin Elevated -> NSTEMI │
• │ • Target door-to-balloon <= 90 min │ │ • Troponin Negative -> Unstable Angina │
• │ • High early transmural necrosis risk │ │ • Medical stabilization + risk score │
• └─────────────────────────────────────────┘ └─────────────────────────────────────────┘
• Clinical Classification

ST-Segment Elevation Myocardial Infarction (STEMI) : Complete, persistent epicardial coronary artery occlusion by an occlusive thrombus resulting in transmural myocardial ischemia and necrosis. Characterized by acute ST-segment elevation or equivalent repolarization abnormalities on a 12-lead electrocardiogram (ECG) and subsequent elevation of cardiac biomarkers.

Non-ST-Segment Elevation Myocardial Infarction (NSTEMI) : Subtotal, intermittent, or micro-embolizing coronary occlusion resulting in subendocardial myocardial necrosis. Diagnosed by objective biomarker evidence of myocardial cell injury (elevated cardiac troponin) in the absence of acute persistent ST-segment elevation.

Unstable Angina (UA) : Myocardial ischemia at rest, new-onset severe angina (CCS Class III or IV), or accelerating/crescendo angina in the absence of detectable myocardial necrosis (persistently normal serial high-sensitivity cardiac troponins). Pathophysiologically identical to NSTEMI, but representing an earlier or less severe ischemic insult without irreversible myocyte death.

12-Lead Electrocardiographic Diagnostic Criteria

Prompt acquisition and physician interpretation of a standard 12-lead ECG is the cornerstone of ACS evaluation and must occur within 10 minutes of first medical contact (FMC).

Standard STEMI Diagnostic Cutoffs

According to the Fourth Universal Definition of Myocardial Infarction, STEMI requires new or presumed-new ST-segment elevation measured at the J-point in at least two anatomically contiguous leads :

Standard Contiguous Leads (I, aVL, II, III, aVF, V4, V5, V6) : ST elevation >= 1.0 mm (0.1 mV at standard calibration of 10 mm = 1 mV).

Precordial Leads V2 and V3 : Because healthy individuals (particularly young men) demonstrate physiological J-point elevation, age- and sex-specific criteria are mandatory:

Women (any age) : >= 1.5 mm (0.15 mV).

Men >= 40 years : >= 2.0 mm (0.2 mV).

Men < 40 years : >= 2.5 mm (0.25 mV).

Anatomical Lead Groupings & Culprit Coronary Vessels

Lead Grouping Anatomical Territory Culprit Coronary Vessel Associated Clinical Complications

II, III, aVF Inferior Wall Right Coronary Artery (RCA, 85–90%) or Left Circumflex (LCx, 10–15%) Sinus bradycardia, high-grade AV block (AV nodal artery ischemia), RV infarction

V1, V2 Septal Wall Left Anterior Descending (LAD - septal perforators) Infranodal conduction block (RBBB, complete heart block), ventricular septal defect

V3, V4 Anterior Wall Left Anterior Descending (LAD - diagonal/distal) Apical aneurysm, LV mural thrombus, acute cardiogenic shock, flash pulmonary edema

V1–V6, I, aVL Extensive Anterolateral Proximal LAD or Left Main Coronary Artery (LMCA) Severe pump failure, cardiogenic shock, malignant ventricular tachyarrhythmias

I, aVL, V5, V6 Lateral Wall Left Circumflex (LCx) or diagonal branch of LAD Papillary muscle dysfunction, acute mitral regurgitation

V7, V8, V9 True Posterior Wall Left Circumflex (LCx) or distal RCA Isolated circumflex occlusion; missed on standard 12-lead unless posterior leads placed

V4R, V5R, V6R Right Ventricle Proximal Right Coronary Artery (RCA) Preload collapse, severe hypotension with nitrates, clear lungs with elevated JVP

Left Bundle Branch Block & The Modified Sgarbossa Criteria

Baseline left bundle branch block (LBBB) alters early ventricular septal depolarization (from right to left) and delays left ventricular activation, producing deep QS complexes in V1–V3 and broad, notched R waves in I, aVL, and V6. Under normal physiological conditions, repolarization is discordant with depolarization (i.e., ST segments and T waves are deflected in the direction opposite to the main QRS deflection). This baseline discordance obscures typical ischemic ST elevation.

While historic guidelines considered any "new or presumed new LBBB" as an automatic STEMI equivalent, contemporary data reveal that <10% of patients with new LBBB have acute coronary occlusion. Instead, clinicians must apply the validated Modified Smith-Sgarbossa Criteria to diagnose acute occlusive myocardial infarction in the presence of LBBB or ventricular paced rhythms: MODIFIED SGARBOSSA CRITERIA

• ┌────────────────────────────────────────────────────────────────────────────────────────┐
• │ 1. CONCORDANT ST ELEVATION (5 Points) │
• │ • ST elevation >= 1.0 mm in >= 1 lead with a predominantly positive QRS complex │
• │ • Highest specificity (>98%, positive likelihood ratio ~25); STEMI equivalent │
• └────────────────────────────────────────────────────────────────────────────────────────┘
• │
• ┌───────────────────────────────────────────┴────────────────────────────────────────────┐
• │ 2. CONCORDANT ST DEPRESSION (3 Points) │
• │ • ST depression >= 1.0 mm in leads V1, V2, or V3 │
• │ • Reflects posterior/septal transmural injury; specificity >95% (LR+ ~11) │
• └────────────────────────────────────────────────────────────────────────────────────────┘
• │
• ┌───────────────────────────────────────────┴────────────────────────────────────────────┐
• │ 3. MODIFIED SMITH CRITERION: EXCESSIVELY DISCORDANT ST ELEVATION │
• │ • Discordant ST elevation >= 1.0 mm with an ST / S ratio <= -0.25 (i.e., |ST/S| >= 25%)│
• │ • Replaces original arbitrary >=5 mm rule; boosts sensitivity from 52% to 91% (spec 90%)│
• └────────────────────────────────────────────────────────────────────────────────────────┘

Clinical Application : A Sgarbossa score >= 3 or a positive Modified Smith criterion (|ST/S| >= 25%) warrants immediate emergency activation of the cardiac catheterization laboratory for primary PCI.

Posterior Myocardial Infarction: Recognition & Verification

Occlusion of the left circumflex artery or a dominant distal right coronary artery frequently results in isolated transmural necrosis of the basal and posterior walls of the left ventricle. Because standard 12-lead ECG electrodes are placed anteriorly, posterior ST elevation is not directly recorded; instead, anterior precordial leads (V1–V3) record reciprocal mirror-image changes:

Lead V1–V3 Hallmarks :

Horizontal or downsloping ST-segment depression (reciprocal to posterior ST elevation).

Prominent, tall, broad R waves with an R/S ratio > 1.0 or R-wave duration >= 40 ms (reciprocal to posterior Q waves).

Upright, symmetrical T waves (reciprocal to posterior T-wave inversions).

Confirmatory Posterior Lead Placement (V7–V9) :

Whenever unexplained ST depression is noted in V1–V3, posterior leads must be placed immediately:

V7 : Posterior axillary line in the 5th intercostal space.

V8 : Mid-scapular line at the inferior angle of the left scapula in the 5th intercostal space.

V9 : Left paraspinal border in the 5th intercostal space.

Diagnostic Threshold : ST-segment elevation >= 0.5 mm (0.05 mV) in at least one posterior lead (or >= 1.0 mm in men < 40 years) confirms posterior STEMI and mandates immediate emergent reperfusion.

Right Ventricular Myocardial Infarction (RVMI)

Right ventricular infarction complicates approximately 30% to 50% of acute inferior STEMIs and results from proximal occlusion of the right coronary artery upstream of the acute marginal branches.

Clinical Presentation & Hemodynamics

The Classic Triad : Hypotension, elevated jugular venous pressure (often with Kussmaul sign: an abnormal inspiratory rise in JVP), and completely clear lung fields (absence of left ventricular pulmonary edema).

Preload Dependence : The ischemic right ventricle is acutely dilated, hypokinetic, and non-compliant. Because the RV cannot generate adequate forward force to overcome normal pulmonary vascular resistance, right ventricular end-diastolic volume and forward output depend almost entirely on elevated right atrial venous filling pressures (preload).

Electrocardiographic Recognition

Standard ECG Suspicion : Inferior ST elevation where lead III elevation is greater than lead II (ST elevation in III > II), accompanied by ST elevation in V1 with reciprocal ST depression in V2.

Right-Sided ECG Confirmation : Obtain a right-sided precordial ECG immediately. ST elevation >= 1.0 mm in lead V4R (placed in the 5th intercostal space in the right midclavicular line) is the most sensitive and specific marker of acute RV involvement.

Fatal Pharmacologic Pitfalls & Hemodynamic Management

ABSOLUTE PHARMACOLOGIC CONTRAINDICATION : Do NOT administer sublingual or intravenous nitroglycerin , morphine , or diuretics . Venodilation and volume depletion cause a sudden, precipitous drop in right ventricular preload. Deprived of filling pressure, the infarcted RV ceases forward flow, triggering catastrophic cardiovascular collapse, refractory shock, and electromechanical arrest.

Emergency Resuscitation Protocol :

Discontinue all nitrates and preload-reducing agents immediately .

Administer rapid intravenous boluses of isotonic crystalloids (500 to 1,000 mL of 0.9% normal saline or lactated Ringer's) to augment right-sided filling pressure and drive forward flow into the left atrium.

If mean arterial pressure remains depressed despite 1 to 2 liters of fluid resuscitation, initiate inotropic support with dobutamine or vasopressor support with norepinephrine .

Expedite immediate mechanical revascularization via primary PCI to restore right coronary perfusion.

High-Sensitivity Cardiac Troponin (hs-cTn) & Rapid Algorithms

High-sensitivity cardiac troponins (hs-cTnT and hs-cTnI) quantify myocardial necrosis with extraordinary precision, detecting circulating troponin concentrations at nanogram-per-liter (ng/L) thresholds with an analytical coefficient of variation <= 10% at the 99th percentile upper reference limit (URL).

Rapid 0/1-Hour and 0/2-Hour Triage Protocols (ESC/ACC)

Rather than waiting 6 to 12 hours for conventional troponin elevations, high-sensitivity assays evaluate baseline concentration and absolute dynamic delta (Delta) changes over 1 or 2 hours: HIGH-SENSITIVITY TROPONIN ALGORITHM

• ┌────────────────────────────────────────────────────────────────────────────────────────┐
• │ PRESENTATION WITH ACUTE CHEST PAIN (hs-cTn drawn at 0 hours) │
• └───────────────────────────────────────────┬────────────────────────────────────────────┘
• │
• ┌────────────────────────────────┼────────────────────────────────┐
• ▼ ▼ ▼
• ┌─────────────────────────┐ ┌─────────────────────────┐ ┌─────────────────────────┐
• │ RULE-OUT PATHWAY │ │ OBSERVE / INCONCLUSIVE │ │ RULE-IN PATHWAY │
• │ • Baseline hs-cTn very │ │ • Intermediate baseline │ │ • Baseline hs-cTn >3-5x │
• │ low (if pain >3 hrs) │ │ concentration │ │ 99th percentile URL │
• │ • OR low baseline with │ │ • OR non-significant │ │ • OR absolute 1h/2h │
• │ no delta at 1h or 2h │ │ delta change │ │ delta meets rule-in │
• │ • NPV > 99% for MI │ │ • Action: 3-hour hs-cTn │ │ • PPV 75-85% for Type 1 │
• │ • Safe early discharge │ │ + bedside echo / CCTA │ │ MI; urgent angiography│
• └─────────────────────────┘ └─────────────────────────┘ └─────────────────────────┘
• Differential Diagnosis of Troponin Elevation

Elevated cardiac troponin indicates myocardial injury , but is not synonymous with an acute atherothrombotic plaque rupture (Type 1 MI). Clinicians must discern between:

Type 1 Myocardial Infarction : Plaque disruption with occlusive or subocclusive coronary thrombus.

Type 2 Myocardial Infarction : Myocardial necrosis resulting from supply/demand mismatch without acute plaque disruption (e.g., severe tachyarrhythmias, hypertensive emergency, severe hypoxemia, acute blood loss anemia, septic shock).

Non-Ischemic Myocardial Injury : Acute myocarditis, stress (Takotsubo) cardiomyopathy, cardiac contusion, acute heart failure exacerbation.

Extracardiac / Systemic Pathology : Acute pulmonary embolism (acute right ventricular strain), severe sepsis, acute aortic dissection, end-stage renal disease (reduced clearance combined with chronic subclinical micro-injury).

• Immediate Pharmacotherapy for Acute Coronary Syndromes
• 1. Dual Antiplatelet Therapy (DAPT)

Aspirin : 162 to 325 mg non-enteric coated , chewed immediately upon presentation to ensure rapid buccal and gastric absorption (inhibits platelet cyclooxygenase-1 within 15–30 minutes). Maintenance: 81 mg daily indefinitely.

P2Y12 Receptor Antagonists :

Ticagrelor (Brilinta) : Direct-acting, reversible P2Y12 inhibitor. Loading dose: 180 mg orally , followed by 90 mg twice daily . Preferred over clopidogrel for primary PCI and NSTEMI due to superior mortality reduction without requiring hepatic CYP2C19 bioactivation. Common adverse effect: self-limiting central dyspnea.

Prasugrel (Effient) : Potent, irreversible thienopyridine. Loading dose: 60 mg orally , followed by 10 mg daily (reduced to 5 mg daily if body weight < 60 kg or age >= 75 years). Preferred in primary PCI. BLACK BOX CONTRAINDICATION : Prior history of stroke or transient ischemic attack (TIA) due to an unacceptable risk of fatal intracranial hemorrhage.

Clopidogrel (Plavix) : Irreversible prodrug requiring hepatic CYP2C19 activation. Loading dose: 600 mg orally for primary PCI, or 300 mg orally for patients receiving fibrinolytic therapy (withhold loading dose and administer 75 mg if age >= 75 years). Indicated when ticagrelor or prasugrel is contraindicated or unavailable.

2. Parenteral Anticoagulation

Unfractionated Heparin (UFH) : Initial IV bolus 60 units/kg (maximum 4,000 units), followed by continuous infusion at 12 units/kg/h (maximum 1,000 units/h), titrated to a therapeutic aPTT of 50 to 70 seconds. First-line agent during primary PCI and preferred in severe renal insufficiency (eGFR < 30 mL/min). Reversible with protamine sulfate.

Enoxaparin (LMWH) : 1 mg/kg subcutaneously every 12 hours (reduce to 1 mg/kg every 24 hours if CrCl < 30 mL/min). In patients receiving fibrinolysis: initial IV bolus 30 mg followed by 1 mg/kg SC (omit IV bolus if age >= 75).

Bivalirudin : Direct thrombin inhibitor; alternative to heparin in patients with heparin-induced thrombocytopenia (HIT) or high bleeding risk.

3. Anti-Ischemic & Hemodynamic Agents

Nitroglycerin : Sublingual 0.4 mg every 5 minutes up to 3 doses; continuous IV infusion (5 to 10 mcg/min titrated up to 200 mcg/min) for persistent chest pain, hypertension, or acute pulmonary edema.

CONTRAINDICATIONS : Systolic BP < 90 mm Hg, bradycardia (<50 bpm), severe tachycardia (>100 bpm), suspected right ventricular infarction, or phosphodiesterase-5 (PDE-5) inhibitor use within 24 hours (sildenafil, vardenafil) or 48 hours (tadalafil) due to catastrophic vasodilation and death.

Oral Beta-Blockers : Initiate oral cardioselective beta-blockade (e.g., metoprolol tartrate 25–50 mg orally every 6 hours or metoprolol succinate) within the first 24 hours in hemodynamically stable patients.

CONTRAINDICATIONS : Signs of acute decompensated heart failure (pulmonary crackles > 1/3 lung bases, peripheral hypoperfusion), high risk for cardiogenic shock (age > 70, SBP < 120 mm Hg, heart rate > 110 or < 60 bpm), PR interval > 0.24 seconds, second- or third-degree heart block, or cocaine-induced chest pain (risk of unopposed alpha-1 adrenergic stimulation exacerbating coronary spasm and hypertension).

High-Intensity Statin : Atorvastatin 80 mg or rosuvastatin 40 mg initiated immediately prior to or upon admission, regardless of baseline LDL-C levels, for plaque stabilization and pleiotropic anti-inflammatory effects.

Supplemental Oxygen : Indicated ONLY if ambient pulse oximetry SpO2 < 90% or the patient is in overt respiratory distress. Hyperoxia triggers coronary vasoconstriction, enhances free radical generation, and increases infarct size and mortality in normoxic patients.

Reperfusion Strategies & Timelines for STEMI STEMI REPERFUSION DECISION TIMELINE

• ┌────────────────────────────────────────────────────────────────────────────────────────┐
• │ PATIENT ARRIVAL WITH CONFIRMED 12-LEAD ECG STEMI │
• └───────────────────────────────────────────┬────────────────────────────────────────────┘
• │
• ┌────────────────────────────────┴────────────────────────────────┐
• ▼ ▼
• ┌─────────────────────────────────────────┐ ┌─────────────────────────────────────────┐
• │ PCI-CAPABLE FACILITY │ │ NON-PCI-CAPABLE FACILITY │
• │ • Primary PCI preferred strategy │ │ • Assess anticipated transfer delay │
• │ • Benchmark: Door-to-Balloon <= 90 min │ │ • FMC-to-Device <= 120 min achievable? │
• └─────────────────────────────────────────┘ └────────────────────┬────────────────────┘
• │
• ┌────────────────────────────────┴────────────────┐
• ▼ ▼
• ┌─────────────────────────┐ ┌─────────────────────────┐
• │ YES: FMC-to-Device <=120│ │ NO: Delay > 120 min │
• │ • Transfer for primary │ │ • FIBRINOLYTIC STRATEGY │
• │ PCI immediately │ │ • Door-to-Needle <= 30m │
• │ • Door-In-Door-Out <=30m│ │ • Check Contraindication│
• └─────────────────────────┘ └─────────────────────────┘
• Benchmarks & Decision Pathways

Primary PCI : Gold-standard mechanical reperfusion for all patients presenting within 12 hours of symptom onset.

Door-to-Balloon Time : <= 90 minutes for patients presenting directly to a PCI-capable facility.

First Medical Contact (FMC) to Balloon Time : <= 120 minutes for patients presenting to a non-PCI facility who require transfer. Door-in-door-out (DIDO) time at the transferring facility should be <= 30 minutes .

Fibrinolytic Therapy : Indicated when primary PCI cannot be accomplished within 120 minutes of FMC, provided symptom onset is < 12 hours and no absolute contraindications exist.

Door-to-Needle Time : Administer weight-adjusted IV fibrinolytic within <= 30 minutes of arrival.

Preferred Agent : Tenecteplase (TNK-tPA) administered as a single weight-based IV bolus over 5 seconds (simplifies dosing and avoids pump infusion delays compared to alteplase). Reduce dose by 50% in patients >= 75 years.

Absolute Contraindications to Fibrinolytic Therapy (Must Memorize)

Any prior intracranial hemorrhage (ICH) at any time.

Known structural cerebral vascular lesion (e.g., arteriovenous malformation, aneurysm).

Known malignant intracranial neoplasm (primary or metastatic).

Ischemic stroke within the past 3 months (excluding acute ischemic stroke within 4.5 hours being actively treated).

Suspected acute aortic dissection .

Active internal bleeding or bleeding diathesis (excluding menses).

Significant closed-head trauma or facial trauma within the past 3 months .

Intracranial or intraspinal surgery within the past 2 months .

Severe uncontrolled hypertension refractory to emergency therapy (systolic BP > 180 mm Hg or diastolic BP > 110 mm Hg).

Post-Fibrinolysis Pharmacoinvasive Strategy

Following fibrinolysis, transfer the patient immediately to a PCI-capable center:

Failed Fibrinolysis (< 50% ST resolution at 60–90 minutes post-bolus or persistent hemodynamic instability): Perform emergency rescue PCI .

Successful Fibrinolysis (>= 50% ST resolution and pain relief): Perform routine scheduled coronary angiography and stenting between 2 and 24 hours post-fibrinolysis.

Loading diagram... STEMI Reperfusion Algorithm and Time Benchmarks