Diagnosis

Myocardial infarction

Etiology

Causes [g0z]

• Type 1: Spontaneous

  • Plaque rupture

  • Ulceration

  • Fissuring

  • Erosion

  • Aortic dissection with involvement of ostia --> intraluminal thrombus

• Type 2: Secondary to increased oxygen demand or a decreased supply

  • Coronary artery spasm

  • Vasculitis

  • Congenital coronary anomalies

  • Coronary artery embolus

  • Tachyarryhthmias/bradyarrhythmias

  • Anemia

  • Respiratory failure

  • Hypertension

  • Hypotension

• Type 3: Sudden cardiac death without available blood sample for biomarkers

• Type 4a: Related to PCI

• Type 4b: Related to stent thrombosis

• Type 5: Related to coronary artery bypass grafting

Pathophysiology [yzw]

1. Ischemia = supply of oxygen < demand of oxygen

   • Preload

   • Afterload

   • Wall thickness

   • Heart rate

   • Contractility

2. Atherosclerotic plaque --> stenosis --> impedes flow

   • Cross-sectional area is reduced by 75% = 50% reduction in diameter

3. Intermittent closure of dynamic plaques --> unstable angina

4. Thrombosis or plaque rupture --> occlusion >20 minutes --> myocardial infarction

5. Depending on the territory and the thickness affected by the infarction, the cardiac function is compromised:

   • Unstable angina: cardiac chest pain + normal ECG/biomarkers

   • NSTEMI: cardiac chest pain + elevated cardiac biomarker levels

   • STEMI: chest pain + ST-segment elevation + elevated cardiac biomarker levels

6. Negligible regeneration capacity --> scar formation

7. Remodeling: dilation, segmental hypertrophy of remaining viable tissue, and cardiac dysfunction

Complications

• Malignant ventricular arrhythmia

• Ventricular wall rupture

• Ventricular septal defect

• Papillary muscle rupture with severe mitral regurgitation

• Ventricular aneurysm formation

Risk factors [yzw]

• Hypertension

• Smoking

• Hypercholesterolemia

• Obesity

• Diabetes mellitus

• Family history

Epidemiology

Incidence per 100.000 [pwn][63h][6ct][yqb]

Approach

• Blood test: Troponin, CK-MB, lipid profile, complete blood cell count

• ECG

• Stress test

• Echocardiography

• Angiography

• Chest x-ray

Treatment

1. Prehospital care: [g0z]

   • Intravenous access

   • Pulse oximetry --> Supplemental oxygen if SaO2 < 90%

   • Aspirin 300mg

   • Nitroglycerin 0.4mg sublingually/spray

   • Pain: Morphine 2-4 mg IV repeated every 5-10 minutes until relieved

   • Telemetry and prehospital ECG

2. STEMI:

   • <90 minutes: emergent coronary angiography, primary PCI, drug-eluting stent

   • >120 minutes from a PCI-capable facility --> fibrinolysis

   • Coronary artery bypass grafting: cardiogenic shock, failed PCI, high-risk anatomy

3. NSTEMI:

   • Anti-ischemic therapy

   • May be candidates for PCI at admission

4. Treatment on long term:

   • Anticoagulants

   • Antiplatelet agents

   • Beta blockers

   • Statins

   • Angiotensin-converting enzyme (in some patients)

   • Lifestyle modifications

Differential diagnoses

Abdominal compartment syndrome, Angina pectoris, Anxiety, Aortic dissection, Aortic regurgitation, Aortic stenosis, Arrhythmia, Asthma, Cholangitis, Cholecystitis, Cholelithiasis, COPD, Depression, Endocarditis, Esophageal spasm, Esophagitis, Gastritis, Gastroesophageal reflux disease, Herpes zoster, Mitral regurgitation, Myocarditis, Pericarditis, Pleuritis, Pneumonia, Pneumothorax, Pulmonary embolism, Ruptured aortic aneurysm, Shock