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Thursday, 22 May 2025

"Saving Lives: Your Guide to Myocardial Infarction Awareness"



- Myocardial infarction, or heart attack, occurs when blood flow to the heart is blocked, often by plaque build-up.

- Common symptoms include chest pain, shortness of breath, and nausea, but they can vary, especially in women and the elderly.

- Risk factors include smoking, high blood pressure, and family history, among others.

- The evidence leans toward immediate treatment with aspirin and procedures like angioplasty to restore blood flow.

 

*Definition -

Myocardial infarction, commonly known as a heart attack, happens when the blood supply to part of the heart is severely reduced or blocked, usually due to plaque (cholesterol-containing deposits) in the coronary arteries. This blockage can lead to heart muscle damage or death if not treated promptly.

 

*Symptoms -

Symptoms often include chest pain or discomfort, which may feel like pressure, tightness, or squeezing, and can radiate to the shoulder, arm, back, neck, jaw, or upper belly. Other signs include shortness of breath, cold sweat, fatigue, nausea, vomiting, and lightheadedness. Some people, especially women and the elderly, may have atypical symptoms like neck or arm pain, or even silent heart attacks with no noticeable symptoms.

 

*Causes and Risk Factors -

The main cause is coronary artery disease, where plaque build-up narrows arteries, potentially leading to a complete blockage if a plaque ruptures and forms a clot. Other causes include coronary artery spasms, infections like COVID-19, and spontaneous coronary artery dissection. Risk factors include age (men ≥45, women ≥55), smoking, high blood pressure, high cholesterol, diabetes, obesity, family history, sedentary lifestyle, unhealthy diet, stress, and conditions like preeclampsia or autoimmune diseases.

 

*Diagnosis and Treatment -

Diagnosis typically involves an ECG to detect heart muscle damage and blood tests for cardiac biomarkers like troponin. Treatment is urgent, often starting with aspirin to prevent further clotting and nitroglycerin for pain relief. Procedures like percutaneous coronary intervention (PCI) or thrombolysis are used to restore blood flow, especially within the first few hours. Long-term management includes medications like beta-blockers and statins, plus lifestyle changes.

 

*Prevention -

Preventing heart attacks involves a heart-healthy lifestyle: regular exercise (e.g., 150 minutes of moderate activity weekly), a diet low in saturated fats and salt, quitting smoking, and managing conditions like hypertension. Medications like statins may be recommended, and learning CPR can be lifesaving in emergencies.

 

*Comprehensive Overview of Myocardial Infarction -

 

Myocardial infarction, commonly referred to as a heart attack, is a critical medical condition characterized by the sudden blockage of blood flow to a portion of the heart muscle, leading to tissue death due to oxygen deprivation. This condition is a leading cause of death globally, with significant implications for public health and individual well-being. The following sections provide a detailed examination of its definition, symptoms, causes, risk factors, diagnosis, treatment, and prevention strategies, drawing from authoritative sources to ensure accuracy and depth.

 

*Definition and Classification -

Myocardial infarction (MI) occurs when the flow of blood to the heart is severely reduced or blocked, typically due to plaque build-up (atherosclerosis) in the coronary arteries, which can rupture and form a clot, causing complete or partial obstruction. It is classified into two main types based on electrocardiogram (ECG) findings:

- **ST Elevation Myocardial Infarction (STEMI)**: Involves acute, complete blockage of a medium or large coronary artery, accounting for 25–40% of MIs.

- **Non-ST Elevation Myocardial Infarction (NSTEMI)**: Involves partial blockage, sometimes with total occlusion of smaller arteries.

 

This classification is crucial for determining treatment urgency and approach.

 

*Symptoms and Presentation -

The symptoms of MI can vary widely, affecting recognition and timely intervention. Common manifestations include:

- Chest pain or discomfort, often described as pressure, tightness, squeezing, or aching, typically retrosternal and radiating to the left shoulder, arm, or jaw.

- Pain spreading to the shoulder, arm, back, neck, jaw, teeth, or upper belly, sometimes mimicking heartburn.

- Shortness of breath, nausea, vomiting, cold sweat, fatigue, and lightheadedness or sudden dizziness.

 

Atypical presentations are notable, particularly in women, the elderly, and diabetics, who may experience:

- Neck pain, arm pain, or fatigue instead of chest pain.

- Silent MIs, representing 22–64% of all infarctions, more common in the elderly and those with diabetes, where symptoms are minimal or absent.

 

Warning signs may precede the event by hours, days, or weeks, such as recurring angina (chest pain or pressure not relieved by rest), highlighting the importance of awareness.

 

*Causes and Underlying Mechanisms -

The primary cause of MI is coronary artery disease (CAD), characterized by the accumulation of atherosclerotic plaque in the coronary arteries. This plaque, composed of cholesterol, cellular waste, and other substances, can rupture, leading to thrombus formation and total occlusion of the artery. Less common causes include:

- Coronary artery spasms, potentially triggered by cocaine use, significant emotional stress (e.g., Takotsubo syndrome), or extreme cold.

- Certain infections, such as COVID-19, which may contribute to vascular inflammation.

- Spontaneous coronary artery dissection (SCAD), more prevalent in women and associated with pregnancy or connective tissue disorders.

 

*Risk Factors and Epidemiology -

Numerous risk factors contribute to the likelihood of experiencing an MI, categorized as modifiable and non-modifiable:

- **Non-Modifiable**: Age (men ≥45, women ≥55), male sex, family history of early heart attack (before age 55 for males, 65 for females).

- **Modifiable**: Smoking (causing 36% of CAD cases), high blood pressure, high cholesterol or triglycerides, diabetes, obesity (20% contribution), sedentary lifestyle (7–12% contribution), unhealthy diet (high in sugars, animal fats, processed foods, trans fats, salt), excessive alcohol intake, stress, and illegal drug use (e.g., cocaine, amphetamines).

- **Additional Factors**: Shift work, combined oral contraceptive pills, non-steroidal anti-inflammatory drugs, endometriosis under 40, air pollution, infections (e.g., Chlamydophila pneumoniae, influenza), Kawasaki disease, high homocysteine levels, and genetics (27 genetic variants, strongest association with chromosome 9p21, genes like PCSK9, SORT1, CDKN2A/2B).

 

*Diagnosis: Methods and Criteria -

Diagnosing MI involves a combination of clinical assessment, imaging, and laboratory tests to confirm myocardial damage:

- **Electrocardiogram (ECG)**: Detects changes such as ST elevation, T wave inversion, new Q waves, or left bundle branch block, crucial for classifying STEMI versus NSTEMI.

- **Blood Tests**: Measure cardiac biomarkers, with troponin preferred due to its specificity (rises within 2–3 hours, peaks in 1–2 days), and CK-MB as an alternative, though less specific.

- **Coronary Angiography**: Provides visualization of blockages, guiding intervention strategies.

- **Diagnostic Criteria**: Defined by elevated cardiac biomarkers with a rising/falling trend, plus at least one of: symptoms of ischemia, ECG changes, new pathological Q waves, or imaging evidence of new loss of viable myocardium or regional wall motion abnormality.

 

*Treatment: Acute and Long-Term Management -

Treatment of MI is time-critical, aiming to restore blood flow and prevent further damage:

- **Immediate Actions**:

  - Administer aspirin (if not allergic) to prevent further clotting.

  - Use nitroglycerin for chest pain relief, and consider opioids for severe pain, though they do not improve mortality outcomes.

  - Supplemental oxygen for those with low oxygen levels or shortness of breath.

- **Emergency Interventions**:

  - **For STEMI**: Percutaneous coronary intervention (PCI) within 90–120 minutes, or thrombolysis (e.g., tissue plasminogen activator, reteplase, streptokinase, tenecteplase) within 30 minutes if PCI is delayed.

  - **For NSTEMI**: Manage with heparin, and PCI within 1–3 days for high-risk patients, using P2Y12 inhibitors (e.g., clopidogrel, prasugrel, ticagrelor), heparins, and glycoprotein IIb/IIIa inhibitors as needed.

- **Post-MI Management**:

  - Aspirin indefinitely, dual antiplatelet therapy (aspirin + P2Y12 inhibitor) for up to 12 months.

  - Beta-blockers within 24 hours, ACE inhibitors within 24 hours and continued indefinitely, statins for cholesterol management, and aldosterone antagonists for left ventricular dysfunction.

  - Rescue PCI for cardiogenic shock or poor response to thrombolysis.

  - Cardiac rehabilitation and influenza vaccine (15–45% benefit) to reduce recurrence risk.

 

 

*Prevention: Primary and Secondary Strategies -

Preventing MI involves both primary prevention (reducing initial risk) and secondary prevention (preventing recurrence):

- **Primary Prevention**:

  - **Lifestyle Changes**: Engage in 150 minutes of moderate or 75 minutes of vigorous aerobic exercise weekly, maintain a healthy weight, quit smoking, limit alcohol, and follow a Mediterranean diet low in saturated fats, trans fats, and salt.

  - **Dietary Interventions**: Substitute unsaturated fats, and support public health measures like food labeling and reducing salt/saturated/trans fats in processed foods.

  - **Medications**: Statins for elevated risk, with aspirin use debated due to bleeding risk (consult healthcare provider).

- **Secondary Prevention**:

  - Lifestyle modifications: Stop smoking, gradual exercise after 1–2 weeks, healthy diet low in saturated fat and cholesterol.

  - Medications as outlined in long-term management.

  - Participate in cardiac rehabilitation programs.

  - Annual influenza vaccination, shown to reduce MI risk by 15–45%.

 

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