Why do heart attacks happen

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Last updated: April 8, 2026

Quick Answer: Heart attacks occur when blood flow to part of the heart muscle is blocked, typically by a buildup of plaque in coronary arteries that ruptures and forms a clot. In the United States, someone has a heart attack every 40 seconds, with about 805,000 Americans experiencing one annually. The most common cause is coronary artery disease, which accounts for approximately 90% of cases, and symptoms often include chest pain, shortness of breath, and nausea.

Key Facts

Coronary artery disease causes about 90% of heart attacks
In the U.S., someone has a heart attack every 40 seconds
About 805,000 Americans experience a heart attack annually
Heart disease is the leading cause of death globally, responsible for 16% of all deaths in 2019
The term 'myocardial infarction' was first described in medical literature in 1912 by James B. Herrick

Overview

Heart attacks, medically termed myocardial infarctions, represent a critical medical emergency where blood flow to a section of the heart muscle becomes obstructed, leading to tissue damage or death. The historical understanding of heart attacks evolved significantly in the 20th century; before the 1910s, they were often misdiagnosed as indigestion or other conditions. In 1912, American physician James B. Herrick published a landmark paper describing coronary thrombosis as the cause, revolutionizing diagnosis. By the 1950s, advancements like electrocardiograms (ECGs) and cardiac enzyme tests improved detection. Today, heart disease remains the leading global cause of death, with the World Health Organization reporting it accounted for 16% of all deaths in 2019, totaling about 8.9 million fatalities worldwide. Risk factors include age, genetics, and lifestyle choices, with men over 45 and women over 55 at higher risk.

How It Works

Heart attacks primarily result from atherosclerosis, a process where fatty deposits called plaque build up in the coronary arteries that supply blood to the heart. Over time, this plaque can rupture, triggering the formation of a blood clot that blocks the artery. This blockage prevents oxygen-rich blood from reaching heart muscle cells, causing ischemia (lack of oxygen) and, if prolonged, necrosis (cell death). The mechanism involves the release of inflammatory substances and platelets that aggregate at the rupture site. In about 90% of cases, this is due to coronary artery disease, but other causes include coronary artery spasm or embolism. Symptoms arise as the heart struggles to pump effectively, leading to chest pain, shortness of breath, and potential complications like arrhythmias or heart failure. Immediate treatment often involves medications like aspirin or clot-busters, and procedures like angioplasty to restore blood flow.

Why It Matters

Heart attacks have profound real-world impacts, being a leading cause of death and disability globally. In the U.S. alone, they result in significant healthcare costs, estimated at over $200 billion annually in medical expenses and lost productivity. Survivors may face long-term consequences, such as reduced quality of life, increased risk of future cardiovascular events, and mental health issues like depression. Prevention through lifestyle changes—such as quitting smoking, managing blood pressure, and maintaining a healthy diet—can reduce incidence rates. Public awareness campaigns, like the American Heart Association's initiatives, emphasize early recognition and response, as timely treatment within the first hour can improve survival rates by up to 50%. This underscores the importance of education and access to emergency care in saving lives.