Myocardial Infarction
Below is a **complete, concise-but-exhaustive** medical reference for **Myocardial Infarction (MI)** following your required full-detail format.
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# **MYOCARDIAL INFARCTION (MI)**
**(Heart Attack – STEMI/NSTEMI)**
---
## **1. Definition**
Acute myocardial infarction is **irreversible myocardial necrosis** caused by **acute reduction or complete cessation of coronary blood flow**, most commonly due to **coronary artery thrombosis**.
---
## **2. Pathophysiology**
* **Atherosclerotic plaque rupture → platelet aggregation → thrombus formation → coronary occlusion.**
* ↓ Blood flow → **myocardial ischemia** → irreversible cell death after **20–40 min**.
* NSTEMI = partial occlusion; STEMI = complete occlusion.
* Oxygen deprivation → anaerobic metabolism → acidosis → loss of contractility → arrhythmias.
* Inflammatory response peaks at **24–48 hrs**; scar formation takes weeks.
---
## **3. Causes / Risk Factors**
### **Major Causes**
* Atherosclerotic plaque rupture (most common)
* Coronary thrombosis
* Coronary vasospasm (cocaine, Prinzmetal)
* Coronary embolism
### **Risk Factors**
* Hypertension, diabetes, dyslipidemia
* Smoking
* Obesity, sedentary lifestyle
* Family history of premature CAD
* Age, male sex
* Chronic kidney disease
* Stress, stimulant drugs
---
## **4. Clinical Features**
### **Typical Symptoms**
* Central chest pain, pressure, heaviness >20–30 min
* Pain radiating to **left arm, jaw, back**
* Sweating, nausea, vomiting
* Dyspnea
* Sense of impending doom
* Syncope or palpitations
### **Atypical**
* Elderly, diabetic, females → *silent MI*, fatigue, epigastric pain, confusion.
### **Physical Exam**
* Tachycardia or bradycardia
* Hypotension
* S4 gallop
* Pulmonary crackles (heart failure)
* New murmur (papillary muscle rupture → MR)
---
## **5. Investigations & Diagnosis**
### **1. ECG**
* **STEMI:** ST elevation in ≥2 contiguous leads / new LBBB
* **NSTEMI/UA:** ST depression, T-wave inversion
### **2. Cardiac Biomarkers**
* **Troponin I/T:** rise after 3–4h, peak 24h, remain elevated 7–10 days
* CK-MB helps detect reinfarction
### **3. Imaging**
* Echocardiography: wall-motion abnormalities
* Angiography: defines culprit lesion
* CXR: pulmonary edema
### **4. Blood Tests**
* CBC, electrolytes, renal function
* Lipid profile
* HbA1c
---
## **6. Differential Diagnoses**
* Angina (stable/unstable)
* Aortic dissection
* Pulmonary embolism
* Pericarditis
* GERD, gastritis
* Costochondritis
* Pneumothorax
---
## **7. Management (Stepwise)**
### **A. Prehospital (First Aid)**
* Call emergency
* Give **aspirin 300 mg chewable**
* Oxygen only if SpO2 < 90%
* Sublingual **nitroglycerin** if not hypotensive
* Morphine if severe pain
---
### **B. Emergency Department**
#### **MONA-BASH** (updated evidence)
* **M**orphine (if pain severe)
* **O**xygen (if hypoxic)
* **N**itroglycerin
* **A**spirin (loading)
* **B**eta-blocker (if stable)
* **A**nticoagulant
* **S**tatin high-dose
* **H**eparin
---
### **C. STEMI Management**
#### **1. Reperfusion Therapy**
**Primary PCI** (preferred):
* Goal: **within 90 mins** of first medical contact
* Indicated for STEMI <12h (or ongoing ischemia)
**Thrombolysis** (if PCI unavailable within 120 min)
* Tenecteplase / Alteplase
* Best if given within **30 mins** of arrival
* Check contraindications (recent stroke, bleeding)
#### **2. Adjunctive Therapy**
* Antiplatelets:
* **Aspirin 150–300 mg**, then 75 mg/day
* **Clopidogrel/Ticagrelor** loading
* Anticoagulation: **UFH/LMWH**
* Beta-blockers: Metoprolol
* ACE inhibitors/ARBs: start within 24h
* Statins: **Atorvastatin 80 mg**
---
### **D. NSTEMI Management**
* No immediate thrombolysis
* Dual antiplatelet therapy
* Anticoagulation
* Early invasive strategy: angiography within 24–72 hours
* Manage risk based on GRACE/TIMI scores
---
### **E. Complications Management**
* Arrhythmias (VT/VF) → defibrillation
* Cardiogenic shock → inotropes, IABP
* Heart failure → diuretics, oxygen, NIV
* Mechanical rupture → urgent surgery
* Pericarditis → NSAIDs (post-MI Dressler)
---
## **8. Drug Details (Indications, MOA, Dose, ADR, Contraindications, Interactions, Monitoring, Counselling)**
### **1. Aspirin**
* **Indication:** MI acute + secondary prevention
* **MOA:** COX-1 inhibition → ↓ thromboxane A2
* **Dose:** 150–300 mg loading; then 75–100 mg/day
* **ADR:** GI bleeding, dyspepsia
* **Contra:** Active bleeding, NSAID allergy
* **Interactions:** Warfarin, steroids ↑ bleeding
* **Monitoring:** GI issue, bleeding signs
* **Counselling:** Take with food, report black stools
---
### **2. Clopidogrel / Ticagrelor**
* **Indication:** DAPT in MI
* **MOA:** P2Y12 receptor blocker
* **Dose:**
* Clopidogrel 300–600 mg load → 75 mg/day
* Ticagrelor 180 mg load → 90 mg BD
* **ADR:** Bleeding, dyspnea (ticagrelor)
* **Contra:** Active bleeding
* **Interactions:** CYP3A inhibitors
* **Monitoring:** Bruising, hemoglobin
* **Counselling:** Do not stop abruptly
---
### **3. Heparin (UFH / LMWH)**
* **Indication:** Prevent thrombus expansion
* **MOA:** Activates antithrombin III
* **Dose:** UFH IV bolus + infusion / LMWH SC
* **ADR:** Bleeding, HIT
* **Contra:** HIT history
* **Monitoring:** aPTT (UFH)
* **Counselling:** Report bleeding, avoid NSAIDs
---
### **4. Nitroglycerin**
* **Indication:** Chest pain relief
* **MOA:** Venodilation → ↓ preload
* **Dose:** 0.4 mg SL every 5 min × 3
* **ADR:** Headache, hypotension
* **Contra:** PDE-5 inhibitors
* **Counselling:** Sit while taking it
---
### **5. Beta-blockers (Metoprolol)**
* **Indication:** Reduce oxygen demand
* **MOA:** Block β1 receptors
* **Dose:** 25–50 mg BD
* **ADR:** Bradycardia, bronchospasm
* **Contra:** Acute HF, heart block
* **Counselling:** Don’t stop suddenly
---
### **6. ACE inhibitors (Ramipril/Enalapril)**
* **Dose:** Start low → titrate
* **ADR:** Cough, hyperkalemia
* **Contra:** Renal artery stenosis
* **Monitoring:** BP, renal function, K+
---
### **7. Statins (Atorvastatin 80 mg)**
* **MOA:** HMG-CoA reductase inhibitor
* **ADR:** Myopathy, liver enzyme elevation
* **Monitoring:** LFTs, muscle pain
---
## **9. Non-Pharmacologic Measures**
* Cardiac rehabilitation
* Low-fat diet, smoking cessation
* Weight control
* Regular walking
* Control of diabetes, BP, lipids
* Stress reduction
---
## **10. Patient Education / Counselling**
* Recognize warning signs early
* Adhere strictly to medications
* Avoid strenuous activity initially
* Regular follow-ups
* Lifelong heart-healthy habits
---
If you want, I can also give:
✅ **MI Case Scenarios**
✅ **MI 25 Hard MCQs with answers (HTML/CSS/JS in one file)**
✅ **MI SEO Meta Title, Description, Keywords**
Just tell me **what you want next**.
---
# **MYOCARDIAL INFARCTION (MI)**
**(Heart Attack – STEMI/NSTEMI)**
---
## **1. Definition**
Acute myocardial infarction is **irreversible myocardial necrosis** caused by **acute reduction or complete cessation of coronary blood flow**, most commonly due to **coronary artery thrombosis**.
---
## **2. Pathophysiology**
* **Atherosclerotic plaque rupture → platelet aggregation → thrombus formation → coronary occlusion.**
* ↓ Blood flow → **myocardial ischemia** → irreversible cell death after **20–40 min**.
* NSTEMI = partial occlusion; STEMI = complete occlusion.
* Oxygen deprivation → anaerobic metabolism → acidosis → loss of contractility → arrhythmias.
* Inflammatory response peaks at **24–48 hrs**; scar formation takes weeks.
---
## **3. Causes / Risk Factors**
### **Major Causes**
* Atherosclerotic plaque rupture (most common)
* Coronary thrombosis
* Coronary vasospasm (cocaine, Prinzmetal)
* Coronary embolism
### **Risk Factors**
* Hypertension, diabetes, dyslipidemia
* Smoking
* Obesity, sedentary lifestyle
* Family history of premature CAD
* Age, male sex
* Chronic kidney disease
* Stress, stimulant drugs
---
## **4. Clinical Features**
### **Typical Symptoms**
* Central chest pain, pressure, heaviness >20–30 min
* Pain radiating to **left arm, jaw, back**
* Sweating, nausea, vomiting
* Dyspnea
* Sense of impending doom
* Syncope or palpitations
### **Atypical**
* Elderly, diabetic, females → *silent MI*, fatigue, epigastric pain, confusion.
### **Physical Exam**
* Tachycardia or bradycardia
* Hypotension
* S4 gallop
* Pulmonary crackles (heart failure)
* New murmur (papillary muscle rupture → MR)
---
## **5. Investigations & Diagnosis**
### **1. ECG**
* **STEMI:** ST elevation in ≥2 contiguous leads / new LBBB
* **NSTEMI/UA:** ST depression, T-wave inversion
### **2. Cardiac Biomarkers**
* **Troponin I/T:** rise after 3–4h, peak 24h, remain elevated 7–10 days
* CK-MB helps detect reinfarction
### **3. Imaging**
* Echocardiography: wall-motion abnormalities
* Angiography: defines culprit lesion
* CXR: pulmonary edema
### **4. Blood Tests**
* CBC, electrolytes, renal function
* Lipid profile
* HbA1c
---
## **6. Differential Diagnoses**
* Angina (stable/unstable)
* Aortic dissection
* Pulmonary embolism
* Pericarditis
* GERD, gastritis
* Costochondritis
* Pneumothorax
---
## **7. Management (Stepwise)**
### **A. Prehospital (First Aid)**
* Call emergency
* Give **aspirin 300 mg chewable**
* Oxygen only if SpO2 < 90%
* Sublingual **nitroglycerin** if not hypotensive
* Morphine if severe pain
---
### **B. Emergency Department**
#### **MONA-BASH** (updated evidence)
* **M**orphine (if pain severe)
* **O**xygen (if hypoxic)
* **N**itroglycerin
* **A**spirin (loading)
* **B**eta-blocker (if stable)
* **A**nticoagulant
* **S**tatin high-dose
* **H**eparin
---
### **C. STEMI Management**
#### **1. Reperfusion Therapy**
**Primary PCI** (preferred):
* Goal: **within 90 mins** of first medical contact
* Indicated for STEMI <12h (or ongoing ischemia)
**Thrombolysis** (if PCI unavailable within 120 min)
* Tenecteplase / Alteplase
* Best if given within **30 mins** of arrival
* Check contraindications (recent stroke, bleeding)
#### **2. Adjunctive Therapy**
* Antiplatelets:
* **Aspirin 150–300 mg**, then 75 mg/day
* **Clopidogrel/Ticagrelor** loading
* Anticoagulation: **UFH/LMWH**
* Beta-blockers: Metoprolol
* ACE inhibitors/ARBs: start within 24h
* Statins: **Atorvastatin 80 mg**
---
### **D. NSTEMI Management**
* No immediate thrombolysis
* Dual antiplatelet therapy
* Anticoagulation
* Early invasive strategy: angiography within 24–72 hours
* Manage risk based on GRACE/TIMI scores
---
### **E. Complications Management**
* Arrhythmias (VT/VF) → defibrillation
* Cardiogenic shock → inotropes, IABP
* Heart failure → diuretics, oxygen, NIV
* Mechanical rupture → urgent surgery
* Pericarditis → NSAIDs (post-MI Dressler)
---
## **8. Drug Details (Indications, MOA, Dose, ADR, Contraindications, Interactions, Monitoring, Counselling)**
### **1. Aspirin**
* **Indication:** MI acute + secondary prevention
* **MOA:** COX-1 inhibition → ↓ thromboxane A2
* **Dose:** 150–300 mg loading; then 75–100 mg/day
* **ADR:** GI bleeding, dyspepsia
* **Contra:** Active bleeding, NSAID allergy
* **Interactions:** Warfarin, steroids ↑ bleeding
* **Monitoring:** GI issue, bleeding signs
* **Counselling:** Take with food, report black stools
---
### **2. Clopidogrel / Ticagrelor**
* **Indication:** DAPT in MI
* **MOA:** P2Y12 receptor blocker
* **Dose:**
* Clopidogrel 300–600 mg load → 75 mg/day
* Ticagrelor 180 mg load → 90 mg BD
* **ADR:** Bleeding, dyspnea (ticagrelor)
* **Contra:** Active bleeding
* **Interactions:** CYP3A inhibitors
* **Monitoring:** Bruising, hemoglobin
* **Counselling:** Do not stop abruptly
---
### **3. Heparin (UFH / LMWH)**
* **Indication:** Prevent thrombus expansion
* **MOA:** Activates antithrombin III
* **Dose:** UFH IV bolus + infusion / LMWH SC
* **ADR:** Bleeding, HIT
* **Contra:** HIT history
* **Monitoring:** aPTT (UFH)
* **Counselling:** Report bleeding, avoid NSAIDs
---
### **4. Nitroglycerin**
* **Indication:** Chest pain relief
* **MOA:** Venodilation → ↓ preload
* **Dose:** 0.4 mg SL every 5 min × 3
* **ADR:** Headache, hypotension
* **Contra:** PDE-5 inhibitors
* **Counselling:** Sit while taking it
---
### **5. Beta-blockers (Metoprolol)**
* **Indication:** Reduce oxygen demand
* **MOA:** Block β1 receptors
* **Dose:** 25–50 mg BD
* **ADR:** Bradycardia, bronchospasm
* **Contra:** Acute HF, heart block
* **Counselling:** Don’t stop suddenly
---
### **6. ACE inhibitors (Ramipril/Enalapril)**
* **Dose:** Start low → titrate
* **ADR:** Cough, hyperkalemia
* **Contra:** Renal artery stenosis
* **Monitoring:** BP, renal function, K+
---
### **7. Statins (Atorvastatin 80 mg)**
* **MOA:** HMG-CoA reductase inhibitor
* **ADR:** Myopathy, liver enzyme elevation
* **Monitoring:** LFTs, muscle pain
---
## **9. Non-Pharmacologic Measures**
* Cardiac rehabilitation
* Low-fat diet, smoking cessation
* Weight control
* Regular walking
* Control of diabetes, BP, lipids
* Stress reduction
---
## **10. Patient Education / Counselling**
* Recognize warning signs early
* Adhere strictly to medications
* Avoid strenuous activity initially
* Regular follow-ups
* Lifelong heart-healthy habits
---
If you want, I can also give:
✅ **MI Case Scenarios**
✅ **MI 25 Hard MCQs with answers (HTML/CSS/JS in one file)**
✅ **MI SEO Meta Title, Description, Keywords**
Just tell me **what you want next**.
Comments (3)
Medical Student
This was incredibly helpful for my upcoming exam. Thank you!
Nursing Professional
Great explanation of the ECG changes in hyperkalemia!