More than a million Americans have heart attacks each year. A heart attack, or myocardial infarction (MI), is permanent damage to the heart muscle. "Myo" means muscle, "cardial" refers to the heart, and "infarction" means death of tissue due to lack of blood supply.
What Happens During a Heart Attack?
The heart muscle requires a constant supply of oxygen-rich blood to nourish it. The coronary arteries provide the heart with this critical blood supply. If you have coronary artery disease, those arteries become narrow and blood cannot flow as well as they should. Fatty matter, calcium, proteins, and inflammatory cells build up within the arteries to form plaques of different sizes. The plaque deposits are hard on the outside and soft and mushy on the inside.
When the plaque is hard, the outer shell cracks (plaque rupture), platelets (disc-shaped particles in the blood that aid clotting) come to the area, and blood clots form around the plaque. If a blood clot totally blocks the artery, the heart muscle becomes "starved" for oxygen. Within a short time, death of heart muscle cells occurs, causing permanent damage. This is a heart attack.
While it is unusual, a heart attack can also be caused by a spasm of a coronary artery. During a coronary spasm, the coronary arteries restrict or spasm on and off, reducing blood supply to the heart muscle (ischemia). It may occur at rest, and can even occur in people without significant coronary artery disease.
Each coronary artery supplies blood to a region of heart muscle. The amount of damage to the heart muscle depends on the size of the area supplied by the blocked artery and the time between injury and treatment.
Healing of the heart muscle begins soon after a heart attack and takes about eight weeks. Just like a skin wound, the heart's wound heals and a scar will form in the damaged area. But, the new scar tissue does not contract. So, the heart's pumping ability is lessened after a heart attack. The amount of lost pumping ability depends on the size and location of the scar.
Heart Attack Symptoms
Symptoms of a heart attack include:
- Discomfort, pressure, heaviness, or pain in the chest, arm, or below the breastbone
- Discomfort radiating to the back, jaw, throat, or arm
- Fullness, indigestion, or choking feeling (may feel like heartburn)
- Sweating, nausea, vomiting, or dizziness
- Extreme weakness, anxiety, or shortness of breath
- Rapid or irregular heartbeats
Some people have a heart attack without having any symptoms (a "silent" myocardial infarction). A silent MI can occur in anyone, but it is more common among people with diabetes.
What Do I Do if I Have a Heart Attack?
After a heart attack, quick treatment to open the blocked artery is essential to lessen the amount of damage. At the first signs of a heart attack, call for emergency treatment (usually 911). The best time to treat a heart attack is within one to two hours of the first onset of symptoms. Waiting longer increases the damage to your heart and reduces your chance of survival.
Keep in mind that chest discomfort can be described in many ways. It can occur in the chest or in the arms, back, or jaw. If you have symptoms, take notice. These are your heart disease warning signs. Seek medical care immediately.
How Is a Heart Attack Diagnosed?
To diagnose a heart attack, an emergency care team will ask you about your symptoms and begin to evaluate you. The diagnosis of the heart attack is based on your symptoms and test results. The goal of treatment is to treat you quickly and limit heart muscle damage.
Tests to Diagnose a Heart Attack
- ECG . The ECG (also known as EKG or electrocardiogram) can tell how much damage has occurred to your heart muscle and where it has occurred. In addition, your heart rate and rhythm can be monitored.
- Blood tests. Blood may be drawn to measure levels of cardiac enzymes that indicate heart muscle damage. These enzymes are normally found inside the cells of your heart and are needed for their function. When your heart muscle cells are injured, their contents -- including the enzymes -- are released into your bloodstream. By measuring the levels of these enzymes, the doctor can determine the size of the heart attack and approximately when the heart attack started. Troponin levels will also be measured. Troponins are proteins found inside of heart cells that are released when they are damaged by the lack of blood supply to the heart. Detecting troponin in the blood may indicate a heart attack.
- Echocardiography. Echocardiography is an imaging test that can be used during and after a heart attack to learn how the heart is pumping and what areas are not pumping normally. The "echo" can also tell if any structures of the heart (valves, septum, etc.) have been injured during the heart attack.
- Cardiac catheterization. Cardiac catheterization, also called cardiac cath, may be used during the first hours of a heart attack if medications are not relieving the ischemia or symptoms. The cardiac cath can be used to directly visualize the blocked artery and help your doctor determine which procedure is needed to treat the blockage.
What Is the Treatment for a Heart Attack?
Once heart attack is diagnosed, treatment begins immediately -- possibly in the ambulance or emergency room. Drugs and surgical procedures are used to treat a heart attack.
What Drugs Are Used to Treat a Heart Attack?
The goals of drug therapy are to break up or prevent blood clots, prevent platelets from gathering and sticking to the plaque, stabilize the plaque, and prevent further ischemia.
These medications must be given as soon as possible (within one to two hours from the start of your heart attack) to decrease the amount of heart damage. The longer the delay in starting these drugs, the more damage can occur and the less benefit they can provide.
Drugs used during a heart attack may include:
- Aspirin to prevent blood clotting that may worsen the heart attack
- Other antiplatelets, such as Brilinta, Effient, or Plavix, to prevent blood clotting
- Thrombolytic therapy ("clot busters") to dissolve any blood clots in the heart's arteries
- Any combination of the above
Other drugs, given during or after a heart attack, lessen your heart's work, improve the functioning of the heart, widen or dilate your blood vessels, decrease your pain, and guard against any life-threatening heart rhythms.
Are There Other Treatment Options for a Heart Attack?
During or shortly after a heart attack, you may go to the cardiac cath lab for direct evaluation of the status of your heart, arteries, and the amount of heart damage. In some cases, procedures (such as angioplasty or stents) are used to open up your narrowed or blocked arteries.
If necessary, bypass surgery may be performed in the days following the heart attack to restore the heart muscle's supply of blood.
Treatments (medications, open heart surgery, and interventional procedures, like angioplasty) do not cure coronary artery disease. Having had a heart attack or treatment does not mean you will never have another heart attack; it can happen again. But, there are several steps you can take to prevent further attacks.
How Are Future Heart Attacks Prevented?
The goal after your heart attack is to keep your heart healthy and reduce your risks of having another heart attack. Your best bet to ward off future attacks are to take your medications, change your lifestyle, and see you doctor for regular heart checkups.
Why Do I Need to Take Drugs After a Heart Attack?
Drugs are prescribed after a heart attack to:
- Prevent future blood clots
- Lessen the work of your heart and improve your heart's performance and recovery
- Prevent plaques by lowering cholesterol
It is important to know the names of your medications, what they are used for, and how often and at what times you need to take them. Your doctor or nurse should review your medications with you. Keep a list of your medications and bring them to each of your doctor visits. If you have questions about them, ask your doctor or pharmacist.
What Lifestyle Changes Are Needed After a Heart Attack?
There is no cure for coronary artery disease. In order to prevent the progression of heart disease and another heart attack, you must follow your doctor's advice and make necessary lifestyle changes -- quitting smoking, lowering your blood cholesterol, controlling your diabetes and high blood pressure, following an exercise plan, maintaining an ideal body weight, and controlling stress.
When Will I See My Doctor Again After I Leave the Hospital?
Make a doctor's appointment for four to six weeks after you leave the hospital following a heart attack. Your doctor will want to check the progress of your recovery. Your doctor may ask you to undergo diagnostic tests such as an exercise stress test at regular intervals. These tests can help your doctor diagnose the presence or progression of blockages in your coronary arteries and plan treatment.
Call your doctor sooner if you have symptoms such as chest pain that becomes more frequent, increases in intensity, lasts longer, or spreads to other areas; shortness of breath, especially at rest; dizziness, or irregular heartbeats.