What does it mean to have a heart attack?

Envision a heart attack, and you probably think of someone clutching his chest in agony, being rushed to the hospital, maybe even dying before he arrives. While this scenario does occur, the reality is often quite different.

The reason is that heart attacks don't follow a linear path. Symptoms can be severe or subtle. The underlying process that causes a heart attack can differ. People may experience significant heart damage or little to none.

"Not all heart attacks strike in the same way, so diagnosing a heart attack requires the combination of a doctor's judgment, signs and symptoms, and test results," says Dr. Peter Libby, a cardiologist with the Heart and Vascular Center at Harvard-affiliated Brigham and Women's Hospital.

What exactly is a heart attack?

Most heart attacks occur when one of the coronary arteries (the vessels that supply blood to the heart) is unable to deliver enough blood to an area of the heart, or to deliver any at all. The most common underlying cause is formation of fatty plaque in one or more coronary arteries.

There are two different mechanisms that cause this compromised blood flow. Doctors define them as type 1 and type 2 heart attacks. "The distinction is important because the various types of heart attacks may be treated entirely differently," says Dr. Libby. Here is a look at each one.

Type 1. With a type 1 heart attack, the cap over a plaque deposit ruptures and releases chemicals that trigger the formation of a blood clot. The clot blocks the artery, interfering with blood flow to part of the heart.

Type 2. A type 2 heart attack does not involve a ruptured plaque. Instead, it happens when there is a mismatch between the amount of blood a portion of the heart muscle needs and the blood supply in the coronary artery feeding that area of the heart.

The trigger for this type of heart attack can be a condition that puts extra stress on the heart, like the flu or pneumonia, an abnormal heart rhythm resulting in an accelerated heart rate, or a significant spike in blood pressure.

Heart attack symptoms

When a heart attack strikes, it can trigger a variety of symptoms. The most common is the stereotypical chest pain, usually described as crushing, squeezing, pressing, heavy, or occasionally stabbing or burning.

Chest pain tends to be focused either in the center of the chest or just below the center of the rib cage, and it can spread to the arms, abdomen, neck, or lower jaw. It's also possible to have a heart attack and not know it. This is known as a silent heart attack. Symptoms lack the intensity of a classic heart attack. Instead, they can appear as chest discomfort that comes and goes; pain in one or both arms, neck, or jaw; sudden shortness of breath; breaking out in a cold sweat; or feeling nauseated or lightheaded. "Because these symptoms can feel so mild and brief, they often get confused for regular discomforts like indigestion or heartburn," says Dr. Libby.

Diagnosing a heart attack

If you have any suspicion that you may be having a heart attack, don't hesitate: call 911. Once you arrive for medical care, the staff will do a quick review of your symptoms.

With any concern for a heart attack, the doctor will immediately order an electrocardiogram (ECG) and a blood test to measure levels of troponin, a protein in heart muscle cells that spills into the bloodstream when any type of heart damage occurs.

Doctors look for high troponin levels and certain changes in the electrical pattern on the ECG to make a diagnosis. Both tests are used because either one can be normal or show only minimal changes in the earliest stage of a heart attack.

In fact, even with normal ECG and troponin results, emergency department doctors will begin immediate treatment if your symptoms are highly suggestive of a heart attack, especially if you have multiple heart risk factors.

Initial treatment

If your test results suggest you're having either a type 1 or type 2 heart attack, most often the doctor will give you several pills right away. These include aspirin; a high-dose statin, such as atorvastatin (Lipitor) or rosuvastatin (Crestor); and a beta blocker to slow your heart rate and reduce heart stress. You'll also get an intravenous infusion of heparin, a drug that discourages blood clotting.

If you're diagnosed with a likely type 1 heart attack with full artery blockage, the doctor will probably send you to the cardiac catheterization lab for angioplasty and stent placement, a minimally invasive procedure to clear the artery and prop it open. This can restore blood flow to the injured heart muscle and minimize permanent damage.

For a type 2 diagnosis, the goal is to restore the mismatch between blood supply and demand. In addition to the medications noted above, you'll need treatment for any medical problem that stressed the heart, such as an infection or an abnormally fast heart rhythm.

Once your condition is stable, your doctor will design a strategy to help with recovery.

"The goal after the first heart attack is simple — to prevent a second one, and prevent further weakening of the heart muscle that can lead to heart failure," says Dr. Libby. This includes diet changes, exercising regularly, a personalized medication regimen, and perhaps referral for cardiac rehabilitation.

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