How to Diagnose a Heart Attack

heart attack, medically known as myocardial infarction, which occurs when blood flow to parts of the heart suddenly slows or stops, causing damage to the heart muscle. There are approximately 735,000 heart attacks in the United States each year. About 26 percent of women and 19 percent of men will die from the event within a year, according to the American Heart Association (AHA).

Knowing these signs and getting a timely diagnosis can increase your chances of survival and recovery.


The signs and symptoms of a heart attack vary from person to person. For some people, there may be clear signs of symptoms. Others may experience only mild pain that resembles indigestion, while others remain asymptomatic until the onset of cardiac arrest (catastrophic loss of heart function).

Some heart attacks happen spontaneously, but often there are early warning signs hours, days, or even weeks in advance.

The earliest signs may be recurring chest pressure that comes and goes in waves, or sudden, severe chest pain (called angina) that comes with activity.

In order to get prompt treatment, it’s important to know the signs of a heart attack. Here are 11 common and uncommon signs of a heart attack that you should never ignore:

  • chest pain, tightness, or pressure that persists for several minutes
  • nausea, indigestion, heartburn, stomach pain, or vomiting
  • cold sweat for no reason
  • Sudden dizziness or lightheadedness
  • Pain radiating to the left side of the body (usually starting in the chest and moving outward)
  • sore jaw or throat, usually radiating from the chest
  • Sudden fatigue and shortness of breath from activities you would normally tolerate
  • Sudden loud snoring, choking, or gasping while asleep (signs of obstructive sleep apnea)
  • persistent cough with white or pink mucus
  • Swollen ankles, calves, and feet (peripheral edema)
  • Palpitations or irregular heartbeats (Arrhythmia)

If you experience these symptoms suddenly, call 911 or seek emergency care, Especially if you are older, overweight or have diabetes, high cholesterol or high blood pressure.

Even if your symptoms are nonspecific, it’s best to get tested.

According to a 2012 study, European Heart Journalup to 30% of heart disease patients have nonspecific symptoms that can easily be confused with other diseases.

Labs and Testing

Upon arrival at the emergency room, you will undergo a physical examination and a series of tests to not only diagnose acute myocardial infarction (AMI) but also determine its severity.

According to international consensus, AMI is defined as an elevation of major cardiac biomarkers (substances in the blood consistent with cardiac events) accompanied by at least one of the following: ischemia (blood flow restriction), characteristic changes in the electrical activity of the heart (by ECG), evidence of arterial occlusion on angiography, and/or changes in cardiac motion on imaging studies.

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Cardiac Biomarkers

Cardiac biomarkers are substances that are released into the blood when the heart is damaged or stressed. These markers are measurable indicators of heart function and can confirm a heart attack based on elevated levels and timing.

The types of blood tests used to diagnose a heart attack include:

  • Troponin test: The most sensitive blood test to detect myocardial damage, generally 12 hours after a cardiac event
  • Creatinine Kinase (CK-MB) test: measures an enzyme specific to the heart muscle that usually peaks within 10 to 24 hours of the event
  • Glycogen Phosphorylase Isoenzyme BB (GPBB) Test: Measures an enzyme that rises sharply within 7 hours of the event and remains elevated for 1 to 3 hours
  • Lactate dehydrogenase (LDH) test: peaks at 72 hours and may indicate AMI or other conditions involving tissue damage (such as cancer, fractures, and liver disease)
  • Albumin Cobalt Binding (ACB) Test: Measures the amount of cobalt bound to the protein albumin, which decreases after a heart attack
  • Myoglobin test: a protein detection test with low specificity but an earlier peak (about two hours) for early diagnosis
  • Soluble urokinase-type plasminogen activator receptor (suPAR) test: a new cardiac marker to measure immune activation after heart attack

High-sensitivity cardiac troponin is now the standard of choice for biomarker diagnosis of acute heart attack.


An electrocardiogram (ECG) is a device that measures the electrical activity of the heart and generates a graph of the voltage produced by the heartbeat.

The procedure involves attaching a series of electrodes to your chest and extremities. Typically, 10 electrodes are connected to form 12 ECG leads. Each of the 12 wires reads a specific electrical pulse.

Pulses are broadly classified into P waves (associated with atrial contraction), QSR complexes (associated with ventricular contraction), and T waves (associated with ventricular rest).

Changes in the normal ECG pattern can identify many cardiac abnormalities, depending on the pulses (segments) affected.

When diagnosing a heart attack, a healthcare provider will look specifically at the ST segment (the part of the ECG reading that connects the QSR complex to the T wave). Not only can this segment help confirm the diagnosis, it can also tell your doctor what kind of heart disease you have, either ST-segment elevation myocardial infarction (STEMI) with complete obstruction of the coronary artery or non-ST-segment elevation myocardial infarction (NSTEMI), of which only a partial Blockage or narrowing of the coronary arteries.

According to a 2013 report by the AHA and the American College of Cardiology Foundation (ACCF), 25% to 40% of heart attacks can be classified as STEMI.


Imaging plays an important role in the diagnosis and characterization of heart attacks. Different techniques can characterize the nature of arterial occlusion and the extent of myocardial damage.

Commonly used studies include chest X-rays, which use electromagnetic radiation to create two-dimensional images of the heart and blood vessels. Additionally, your healthcare provider may perform an echocardiogram, which uses sound waves to create a live video image of the heart, allowing the practitioner to see how it is pumping and how blood flows from one chamber to another.

Computed tomography (CT) of the heart captures a series of consecutive X-ray images while you lie down in the tubular chamber. These images are then composited by a computer to create a 3D image of the heart’s structure. Magnetic resonance imaging (MRI) of the heart works like a CT scan, but requires powerful magnetic and radio waves to create highly detailed images, especially of soft tissue.

Coronary catheterization (angiography) involves injecting dye into your heart through a thin tube (catheter) that has been fed through an artery in your groin or leg. The dye provides better contrast and clarity for X-ray studies. This procedure is usually for anyone who has had a heart attack.

In the days or weeks after a heart attack, you may also have a cardiac stress test to measure how your heart responds to exertion. You may be asked to walk on a treadmill or pedal a stationary bike while the EKG is connected. If you can’t do physical activity, you may get an intravenous injection to stimulate your heart like exercise.

Your healthcare provider may also recommend a nuclear stress test, an imaging technique that uses a radioactive tracer to assess blood flow through the heart during activity and rest.

Differential diagnosis

Just as a heart attack can be mistaken for other diseases, there are some common and uncommon conditions that can be mistaken for a heart attack. In fact, some conditions have symptoms so similar that a battery of tests is required to differentiate them.

This elimination process, called differential diagnosis, will involve a review of other possible causes of the cardiac event. Examples include:

  • Anxiety or panic attacks, characterized by a lack of abnormal cardiac markers and symptoms such as hyperventilation
  • Aortic dissection, a serious condition involving a tear in the lining of the aorta, differentiated by evidence of tearing on imaging studies
  • Costochondritis, inflammation of the joints of the upper ribs, differentiated by chest discomfort during breathing and normal cardiac biomarkers, electrocardiogram, and imaging studies
  • Gastroesophageal reflux disease (GERD), usually differentiated by physical examination and normal cardiac biomarkers
  • Myocarditis, myocardial inflammation differentiated by cardiac MRI and blood inflammatory markers (using ESR and C-reactive protein tests)
  • Pericarditis, inflammation of the inner layer of the heart (pericardium), distinguished by marked ST-segment depression and evidence of pericardial effusion on echocardiography
  • Pneumonia, differentiated by fluid infiltration of the lungs and increased white blood cell (WBC) counts indicative of infection on chest radiograph
  • Pneumothorax, a collapsed lung differentiated by a chest X-ray
  • Pulmonary embolism, a blood clot in the lung differentiated by abnormal arterial blood gases and a positive D-dimer test (used to diagnose blood clots)
  • Unstable angina, a randomized angina pattern differentiated by normal cardiac biomarkers

Frequently Asked Questions

  • What are the first signs of a heart attack in women?

    For women, chest pain is the most common symptom. However, women were more likely than men to experience other, less specific symptoms, especially nausea, vomiting, shortness of breath, back pain, and jaw pain.

  • How long does a heart attack last?

    Heart attack symptoms like chest pain usually last more than a few minutes. Symptoms can also go away and reappear within a few hours. If you think you’re experiencing the symptoms of a heart attack, don’t wait to see how long the symptoms last. Call 911 and go to the emergency room immediately.

  • How can you tell the difference between an anxiety disorder and a heart attack?

    Heart attacks and anxiety attacks can cause similar symptoms, but they can have subtle differences. While chest pain from a heart attack can radiate to the arms, jaw, or neck, pain from an anxiety attack is usually limited to the chest. A heart attack can feel like pressure, squeezing, pain, or burning, while an anxiety attack often causes a sharp tingling. Since it can be difficult to tell the difference, seek emergency care if you experience any of these symptoms.

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