What is a heart attack?
A heart attack, also known as a myocardial infarction, occurs when blood flow to part of the heart muscle is blocked long enough that the tissue is damaged or dies. This blockage is most often caused by a buildup of plaque—composed of fat, cholesterol, and other substances—in the coronary arteries that supply blood to the heart. If a plaque ruptures, a blood clot can form around it and completely block the artery.
A heart attack is different from cardiac arrest, which is when the heart suddenly stops beating. However, a heart attack can trigger sudden cardiac arrest.
Common symptoms include chest pain or discomfort, shortness of breath, cold sweat, nausea, and lightheadedness. Risk factors include coronary artery disease, high blood pressure, diabetes, smoking, obesity, and substance abuse. A heart attack is a medical emergency requiring immediate treatment to restore blood flow and prevent further damage.
What causes a heart attack?
Atherosclerosis
Atherosclerosis is the buildup of fatty plaques inside arterial walls. Over time, these plaques harden and narrow the arteries, reducing blood flow to the heart muscle.
Plaque rupture
When a plaque cracks or ruptures, a blood clot can form around it. A large enough clot can completely block blood flow through the coronary artery.
Coronary artery spasm
A severe spasm (tightening) of a coronary artery can reduce or block blood flow. Spasms may be triggered by drugs (such as cocaine), stress, cold exposure, or smoking.
Other causes
- Coronary artery dissection: a tear in the artery wall
- Microvascular disease: dysfunction in the small coronary arteries
Risk factors
- High blood pressure
- High LDL cholesterol
- Smoking
- Diabetes
- Obesity
- Physical inactivity
- Unhealthy diet (high in saturated fats, trans fats, cholesterol, sodium)
- Excessive alcohol consumption
- Family history of heart disease
- Age (men over 45, women over 55)
- Chronic stress
- Illegal drug use (cocaine, amphetamines)
- Autoimmune disorders (lupus, rheumatoid arthritis)
What are the symptoms of a heart attack?
Common symptoms
- Chest pain or discomfort: pressure, squeezing, fullness, or pain in the center or left chest
- Upper body discomfort: pain in one or both arms, back, neck, jaw, or stomach
- Shortness of breath: with or without chest discomfort
- Cold sweat
- Nausea or vomiting
- Lightheadedness or dizziness
Less common symptoms
- Unusual fatigue, sometimes days or weeks before
- Indigestion or heartburn
- Anxiety or a sense of impending doom
Symptoms in women
- Unusual fatigue
- Sleep disturbances
- Shortness of breath
- Indigestion or gas-like pain
- Upper back pain
When to seek medical attention
If you or someone else experiences these symptoms, call emergency services immediately (911 in the U.S.). Do not drive yourself to the hospital. Chew and swallow an aspirin (unless allergic) while waiting for help, as it can reduce blood clotting.
How is a heart attack diagnosed?
Medical history and physical exam
- Review of symptoms, onset, duration, and triggers
- Evaluation of personal and family history of heart disease and risk factors
- Vital signs: blood pressure, pulse, oxygen level, temperature
- Heart and lung auscultation
Diagnostic tests
- Electrocardiogram (ECG/EKG): measures electrical activity and detects damage
- Blood tests:
- Troponin: indicates heart muscle injury
- CK-MB: enzyme marker of heart damage
- Other markers: myoglobin, BNP
- Chest X-ray: assesses heart size and lung conditions
- Echocardiogram: ultrasound to visualize heart function and damaged areas
- Coronary angiography: contrast X-ray to identify blockages in coronary arteries
- Cardiac CT or MRI: detailed imaging of heart and vessels
Additional tests
- Stress tests: evaluate heart function during exercise
- Nuclear heart scans: use radioactive tracers to assess blood flow
How is a heart attack treated?
Immediate treatment
- Call emergency services immediately
- Chew and swallow an aspirin
- Nitroglycerin for chest pain (if prescribed)
- CPR or defibrillation if cardiac arrest occurs
Hospital treatments
- Oxygen therapy
- Medications:
- Thrombolytics to dissolve clots
- Antiplatelet agents (aspirin, clopidogrel)
- Anticoagulants (heparin, warfarin)
- Pain relievers (morphine)
- Nitroglycerin to dilate vessels
- Beta-blockers to reduce heart rate and blood pressure
- ACE inhibitors or ARBs to lower blood pressure and reduce strain
- Statins to lower cholesterol and stabilize plaques
- Calcium channel blockers to relax blood vessels
- Percutaneous coronary intervention (PCI):
- Angioplasty: balloon dilation of blocked artery
- Stenting: placement of a mesh tube to keep artery open
- Coronary artery bypass grafting (CABG): surgical rerouting of blood flow around blocked arteries
After you leave the hospital
- Medications: continued antiplatelets, beta-blockers, ACE inhibitors, ARBs, statins
- Lifestyle changes:
- Healthy diet rich in fruits, vegetables, whole grains, lean proteins, healthy fats
- Regular exercise: at least 30 minutes most days
- Smoking cessation
- Weight management
- Moderate alcohol intake (up to 1 drink/day for women, 2 for men)
- Stress reduction: mindfulness, support groups
- Cardiac rehabilitation: supervised exercise, education, counseling
- Regular follow-up appointments to monitor heart health and adjust treatment
Sources
- What is a Heart Attack? American Heart Association (AHA). Accessed May 15, 2024.
- Heart attack. National Heart, Lung, and Blood Institute. Accessed May 15, 2024.
- Heart treatments. National Heart, Lung, and Blood Institute. Accessed May 15, 2024.
- Life After a Heart Attack. American College of Cardiology. Accessed May 15, 2024.
- Boyle AJ. Acute Myocardial Infarction. In: Current Diagnosis & Treatment: Cardiology. 6th ed. McGraw Hill Education; 2023.
- Heart attack symptoms, risk, and recovery. Centers for Disease Control and Prevention. Accessed May 15, 2024.