Myocardial Infarction: Symptoms, Causes, Types and Treatment

Myocardial Infarction, commonly known as a Heart Attack, is a medical emergency where one or more areas of the heart do not get enough oxygen. This happens due to a blockage of blood flow to the heart muscle. If the blood flow isn’t restored promptly, the blockage in coronary arteries can lead to permanent heart damage and death. 

1. STEMI (ST-elevation myocardial infarction): These attacks occur when a coronary artery becomes completely blocked, preventing blood from reaching a large portion of the heart muscle. STEMI is a serious heart attack that causes severe damage and requires immediate attention. 
2. NSTEMI (Non-ST-elevation myocardial infarction): These attacks occur when a coronary artery becomes partially blocked. While NSTEMI is less dangerous than STEMI, it can cause permanent damage. 
3. Coronary Artery Spasm: It is also known as unstable angina or silent heart attack. In this condition, the heart's arteries tighten to the point where the blood flows stops or drastically reduces. There is no permanent damage during coronary artery spasms, and the symptoms can be mistaken for indigestion. 

The common symptoms of myocardial infarction include:

1. Angina (chest pain): Pressure, squeezing, fullness, pain, or discomfort in the centre of the chest that spreads to the shoulders, neck, arm, back, or jaw. 
2. Shortness of breath
3. Anxiety
4. Heart palpitations

Studies show that women usually experience different symptoms than those mentioned above. The symptoms of a heart attack in women include:

1. Shortness of breath
2. Fatigue and insomnia
3. Pain in the back, shoulders, arms, neck, jaw, or abdomen
4. Feeling lightheaded or dizzy
5. Nausea and vomiting
6. Cold sweat

Heart attacks mostly occur due to a blockage in one or more coronary arteries that supply blood to the heart. Blockage in the arteries often occurs due to plaque buildup inside your arteries (atherosclerosis). The condition is referred to as Coronary Artery Disease.

Sometimes, plaque deposits can break open or rupture the coronary arteries, resulting in the formation of a blood clot where the rupture happened. If this clot blocks the artery, the heart muscle gets deprived of blood, leading to a heart attack. 

Some other rare causes of myocardial infarction include:

1. Medical conditions: Any disease that causes narrowing of blood vessels.
2. Spasm of the artery: Blood vessels have a muscle lining that helps them become wider or narrower as needed. Sometimes, these muscles can twitch and rupture, blocking the blood supply to the heart muscle. 
3. Trauma: Tears or ruptures in the coronary arteries.
4. Electrolyte imbalances: Too much or too little minerals like potassium in the blood can lead to a heart attack.
5. Obstruction from elsewhere in the body: A blood clot or air bubble that gets trapped in a coronary artery.
6. Eating disorders: Eating disorders can eventually damage your heart and lead to a heart attack. 

Even if you have already had a heart attack, you can take the following steps to prevent a future heart attack:

1. Take your medications: Taking medications can reduce your risk of a subsequent heart attack and help your damaged heart function properly. Continue taking all the medications prescribed by your doctor. 
2. Schedule regular medical appointments: Get regular checkups to help the doctor diagnose and treat any heart-related conditions at an early stage. 
3. Lifestyle changes: Maintain a healthy weight, exercise regularly, quit smoking, and control conditions such as high blood pressure and cholesterol. 
4. Eat a healthy diet: Eat a heart-healthy diet consisting of whole grains, fruits, vegetables, and proteins. Avoid sugar and processed food in your diet. 
5. Manage your stress: Engage in activities such as meditation, deep breathing, and yoga. 

Several factors can aggravate your risk of having a heart attack. These risk factors include:

1. Age and sex: Men’s risk of heart attack increases at the age of 45, and the risk for women increases after menopause. 
2. Lifestyle: Following an unhealthy lifestyle (lack of physical activity, a diet high in sugar, smoking, or drinking alcohol) increases your risk of a heart attack. 
3. Family history: If your parents or siblings have had a heart attack (by age 55 for males and 65 for females), your heart attack risk increases. 
4. History of preeclampsia: The condition causes high blood pressure during pregnancy. 
5. Stress: Having stress can increase your risk of a heart attack.

Other health conditions: The following conditions increase your risk of myocardial infarction:

1. High blood pressure
2. High blood cholesterol
3. Obesity
4. Diabetes
5. Eating disorders such as anorexia and bulimia 

If you are experiencing the symptoms of a heart attack, your condition will be diagnosed in an emergency room setting. The doctor will enquire about your symptoms and check your vitals, including blood pressure, pulse, and temperature. The team will connect you to a heart monitor and perform some diagnostic tests to see if you have a heart attack. The tests include:

1. Electrocardiogram (ECG): It is the first test to diagnose a heart attack. The doctor attaches electrodes (sticky patches) to your chest and limb to record electric signals travelling through your heart. The electric signals are displayed as waves on the monitor. When the injured heart does not conduct electric signals as it should, the shape of the waves changes, indicating that a heart attack has occurred or is in progress.  
2. Blood tests: During myocardial infarction, the damage to the heart slowly leaks certain heart proteins into the bloodstream. Doctors take a sample of your blood to look for these proteins. 
3. Chest X-ray: An X-ray of your chest helps the doctor examine the size of your heart and its blood vessels to check for fluid in your lungs.
4. Angiogram (cardiac catheterization): The doctor inserts a liquid dye into your coronary arteries through a catheter to look for areas of blockage. 
5. Echocardiogram: The test uses ultrasound (high-frequency sound waves) to create images of the moving heart. It helps your doctor identify whether an area of the heart has been damaged. 
6. Cardiac CT or MRI scans: Cardiac CT scans use X-rays, and MRI uses radio waves and a magnetic field to create images of the heart and chest. The tests are used to diagnose the damage from heart attacks. 

The treatment for a heart attack involves restoring the blood flow to the affected heart muscle with the help of medications, surgeries, or in most cases, a combination of the two. 

Medications

Medications for the treatment of a heart attack include:

1. Nitroglycerin: The medication is used to treat chest pain. It can also widen the blood vessels, improving the blood flow to the heart. 
2. Anti-clotting medications: This includes aspirin to reduce blood clotting and other blood-thinning medications such as heparin. 
3. Thrombolytics: Also called clot busters, these medications help break down and dissolve a blood clot blocking the blood flow to your heart. These are usually used within the first 12 hours of a heart attack. The earlier you receive thrombolytics, the greater your chance of survival. 
4. Antiplatelet agents: These medications help prevent new clots and keep the existing ones from growing. 
5. Beta-blockers: These medicines help relax your heart muscle, decrease blood pressure, and slow your heartbeat. They limit the amount of heart muscle damage during a heart attack. 
6. Antiarrhythmic drugs: Arrhythmias or abnormal heart rhythms can be life-threatening. These medications prevent and treat abnormal heartbeats. 
7. Pain relievers: Pain relievers such as morphine can help reduce chest pain. 
8. ACE inhibitors: Lowers blood pressure and the stress on the heart.
9. Statins: Helps control blood cholesterol. 

Surgical Procedures

Coronary angioplasty and stenting: In this procedure, the doctor guides a long, thin tube known as a catheter via your artery to reach the blockage. He/she inflates a small balloon attached to the catheter to open the blocked coronary artery. In almost all cases, a small mesh tube called a stent is inserted into the artery to keep it open and restore the blood flow. If you have a heart attack, this procedure is performed immediately after cardiac catheterization. 

1. Coronary artery bypass surgery: The procedure is also known as CABG and pronounced as ‘cabbage’. In some cases, the surgery may be performed immediately after a heart attack. However, in most cases, the surgeon performs the procedure three to seven days after your heart has had time to recover from the heart attack. In this procedure, the surgeon reroutes your veins and arteries to restore blood flow around the blockage. 
2. Atherectomy: It is a minimally invasive procedure to remove plaque buildup from the blocked blood vessel. In this procedure, the doctor inserts a catheter into the artery via a small puncture. A sharp blade is attached at the end of the catheter to remove plaque.

A heart attack can damage your heart, leading to:

1. Abnormal heart rhythms or arrhythmias: Some abnormal heart rhythms can be serious, leading to death. 
2. Heart failure: If the heart attack damages enough heart tissue, your heart may weaken and become unable to pump blood effectively, leading to heart failure. 
3. Sudden cardiac arrest: Without immediate treatment, your heart can stop due to abnormal heart rhythms, which can cause death. 

How to Prepare for Doctor Consultation?

Myocardial infarction is diagnosed in an emergency room setting. However, if you think you are at risk of having a heart attack, you can see your doctor and discuss prevention. While preparing for a doctor’s appointment, make sure to:

1. Take a prior appointment
2. Make a list of your medical history and symptoms
3. Note down your questions for the doctor
4. Ask someone to accompany you

Here’s what you can ask your doctor about the prevention of a heart attack:

1. What tests do I need to diagnose my current health condition?
2. How often should I get tested for heart diseases?
3. What amount of physical activity is appropriate?
4. Do I need to make any changes to my diet?

Here’s what you can expect from your doctor:

1. What symptoms do you experience? How severe are they?
2. Do you constantly experience those symptoms?
3. Does anything improve your symptoms?
4. Does anything make them worse?
5. Do you have other health conditions like high blood pressure, cholesterol, or diabetes?
6. Does any of your family members have a history of heart attack?