Myocardial Infarction (heart attack)

Basic Facts

  • Myocardial infarction, commonly referred to as heart attack, is the most serious outcome of coronary artery disease (CAD). Blood flow to the heart muscle is cut off. The longer the blood flow is cut off, the more heart damage is done.
  • Forty-five percent of all heart attacks occur in people younger than 65.

Each heart attack is different and may have different symptoms, but usually presents as a combination of:

  • Chest discomfort that may start out feeling mild and build in intensity,
  • Discomfort in other areas of the upper body, including the neck, arms, shoulders, jaw, or upper back
  • Shortness of breath,
  • Breaking out in a cold sweat,
  • Feeling dizzy, light-headed or nauseated, or
  • Belching or vomiting.

 

Atherosclerosis is the cause of coronary artery disease. It is due to both cholesterol and inflammation. It is caused by plaque that gradually builds up in arteries over time, causing arteries to narrow and reduce blood flow. Plaque is composed of a variety of substances, including cholesterol, calcium, and inflamed cells. When plaque ruptures, it releases these substances into the bloodstream, which leads to the formation of a blood clot inside the artery, which can result in a heart attack. 

Risks for developing atherosclerosis include:

  • Smoking,
  • High cholesterol levels or lipid disorders, - high levels of cholesterol in the blood can increase the risk of plaque buildup,
  • Hypertension or (high blood pressure), - uncontrolled blood pressure can result in hardening and thickening of the arteries,
  • Family history of heart disease, especially in 1st degree relatives under the age of 65,
  • Diabetes – high levels of glucose in the blood can increase risk of plaque buildup,
  • Male gender,
  • Diet high in saturated fats and/or sodium,
  • Advanced age,
  • Obesity and lack of exercise,
  • Alcohol and drug abuse.

 

 

 

The two most common tools physicians use to diagnose MI are electrocardiogram (ECG), a noninvasive test that records the electrical activity of the heart, and a blood test (Troponin) that identifies chemicals associated with heart injury. Other tests a physician may use include: 

  • Stress Test –involves walking on a treadmill while the heart rhythm, blood pressure, and breathing are closely monitored. For people who have difficulty with physical exercise a drug that mimics the effects of exercise may be used instead. 

  • Nuclear Stress Test - This test looks at the blood flow to the heart muscle during rest and after exercise. Before the exercise part of the test, a tracer is injected into the patient’s bloodstream.  Then a special camera can detect areas of the heart that receive less blood flow.  

  • Echocardiogram – painless, noninvasive study that uses ultrasound waves to evaluate heart structure and function in real time. 

  • Cardiac Catheterization and Angiography – This test uses dye and special x-rays to show the insides of the coronary arteries.

Emergency care 

Time is critical! Restoring blood flow to the heart within one hour of the onset of a heart attack can prevent or limit damage to the heart muscle, and it can also decrease the chance of a repeat heart attack. To restore blood flow to the heart muscle, physicians typically use a minimally invasive procedure such as: 

  • Cardiac Catheterization with angioplasty and Stenting - During this non-surgical procedure, a balloon attached to a small catheter is inflated within an artery to flatten the plaque against the artery wall, increasing the artery's diameter. In most cases, a stent, a metal-mesh tube, is expanded and left inside the artery to support the expansion and maintain blood flow. 

  • Thrombolytic Therapy - uses specialized medications to dissolve blood clots 

Post-emergency care 

Once emergency treatment for MI has been administered, , the next goals of treatment become addressing risk factors, preventing further damage to the heart muscle, and minimizing the risk of a repeat MI. 

Medications are used to stabilize plaque and reduce workload on the heart: 

  • Aspirin or other antiplatelet medicines (clopidogrel, ticagrelor, prasugrel) can help prevent obstruction of the coronary arteries. 

  • Beta-blockers lower blood pressure and heart rate, reducing the workload on the heart. 

  • Cholesterol-modifying medications or lipid therapy - help lower the amount of “bad” cholesterol, help stabilize plaque, and reduce risk of MI and stroke. 

  • Nitrates – relax coronary arteries so that blood can flow through them easier.  

  • In some cases, additional angioplasty and stenting or a bypass surgery may be recommended after a heart attack. 

Lifestyle Changes 

There are some beneficial lifestyle changes people can take to minimize their risk of having an acute MI. These changes include: 

  • Quitting smoking, 

  • Controlling high blood pressure, 

  • Lowering cholesterol, 

  • Exercising, 

  • Losing weight, and 

  • Controlling diabetes.