Heart Attack (Myocardial Infarction): Causes, Symptoms, and Treatment
Also known as: Myocardial Infarction, MI
What is a heart attack?
A heart attack (myocardial infarction) is an absolute medical emergency that occurs when a coronary artery becomes blocked, cutting off oxygen to part of the heart muscle. Without enough blood flow, heart muscle cells begin to die within minutes. Each year in the U.S., more than 800,000 people have a heart attack, according to the CDC. It is a serious condition, but survival rates keep improving thanks to medical advances, and getting fast treatment is critical for limiting lasting damage.
Causes and risk factors
A heart attack is mainly caused by atherosclerosis, a gradual buildup of fatty deposits (cholesterol) on the inner walls of the coronary arteries. These plaques can rupture suddenly, triggering a blood clot that blocks the artery. Major risk factors include smoking, high blood pressure, diabetes, high cholesterol, obesity, and a sedentary lifestyle. Heredity also plays an important role. Risk increases with age, and men are generally affected at a younger age than women: the risk of heart disease rises for men after age 45 and for women after age 55, or after menopause.
Symptoms
Signs of a heart attack are often sudden and intense:
- Crushing, squeezing chest pain, sometimes radiating to the left arm, jaw, or back
- Significant shortness of breath, even at rest
- Cold sweats and a general feeling of being unwell
- Nausea or vomiting
- Paleness and intense anxiety
In women, symptoms can be less typical: unusual fatigue, abdominal pain, or simple shortness of breath, which can sometimes delay diagnosis. The pain usually lasts more than 20 minutes and does not ease with rest. This is what separates it from angina, whose pain does settle when you rest.
Diagnosis
When a heart attack is suspected, the doctor or emergency medical team immediately performs an electrocardiogram (EKG), which shows the heart’s electrical activity and reveals characteristic abnormalities. A blood test is done to measure cardiac biomarkers, especially troponin, a protein found in heart muscle cells and released into the bloodstream when those cells are damaged. Troponin usually takes a few hours to rise, so the test is often repeated. A coronary angiogram, an imaging test of the coronary arteries, is often performed to pinpoint the exact location of the blockage.
Available treatments
The priority is restoring blood flow as quickly as possible. Two main approaches are used:
- Coronary angioplasty: a catheter-based procedure to widen the blocked artery and place a stent (a small metal scaffold) to keep it open. U.S. guidelines call for this to be done within 90 minutes of arrival at the hospital.
- Thrombolysis: injecting a clot-dissolving medication, used when angioplasty is not available quickly enough.
Medications are routinely prescribed: antiplatelet drugs (aspirin, clopidogrel), anticoagulants, beta blockers, cholesterol-lowering statins, and ACE inhibitors. Cardiac rehabilitation at a specialized center rounds out care, helping strengthen the heart and reduce the risk of another heart attack.
Prevention and practical tips
Reducing cardiovascular risk factors is the best prevention. Key steps include:
- Quit smoking. Even after a heart attack, the benefit is immediate.
- Eat a balanced diet rich in vegetables, fruit, and unsaturated fats (a Mediterranean-style diet)
- Get regular physical activity: the American Heart Association recommends at least 150 minutes a week of moderate-intensity aerobic activity, or 75 minutes of vigorous activity, plus muscle-strengthening twice a week
- Regularly check your blood pressure, cholesterol, and blood sugar
- Maintain a healthy weight
- Manage chronic stress with relaxation techniques
Regular medical follow-up after a first heart attack is essential for adjusting treatment and preventing another one.
When should you see a doctor?
Call 911 immediately if you feel intense, prolonged chest pain, sudden shortness of breath, unexplained cold sweats, or a feeling of pressure in the chest. Every minute counts: an untreated heart attack can be fatal or cause significant lasting heart damage. Never wait, and do not drive yourself to the ER.
Sources
- MedlinePlus, U.S. National Library of Medicine information on heart attack
- MedlinePlus Troponin Test, how troponin is used to diagnose a heart attack and when levels rise
- National Heart, Lung, and Blood Institute (NHLBI), annual U.S. heart attack figure (CDC data), causes, symptoms, and risk factors
- MedlinePlus, How to Prevent Heart Disease, age at which heart disease risk rises (men 45+, women 55+)
- MedlinePlus, Heart Disease in Women, rise in a woman’s risk during and after menopause
- MedlinePlus, Angina, stable angina pain eases with rest
- StatPearls, Myocardial Infarction (NCBI Bookshelf), duration of heart attack chest pain
- StatPearls, ST-Elevation Myocardial Infarction (NCBI Bookshelf), 90-minute door-to-balloon target for primary PCI
- American Heart Association, treatment of a heart attack
- American Heart Association, physical activity recommendations for adults