A heart attack happens when blood flow to part of your heart muscle gets blocked, starving that tissue of oxygen and causing it to die. The blockage is almost always caused by a blood clot that forms inside a coronary artery, one of the vessels that feed the heart itself. Every minute without blood flow means more muscle damage, which is why fast treatment can be the difference between a full recovery and lasting heart problems.
How a Heart Attack Develops
Heart attacks don’t come out of nowhere. They’re the end result of a process that typically builds over years or even decades. It starts when cholesterol particles (specifically LDL, the “bad” cholesterol) seep into the walls of your coronary arteries. Once inside, those particles get oxidized and trigger an immune response. White blood cells rush in, swallow the cholesterol, and become bloated “foam cells” that pile up into fatty deposits called plaques.
Over time, a plaque develops a soft, unstable core covered by a thin fibrous cap. Think of it like a blister under the surface of the artery wall. If that cap cracks or tears open, the contents of the plaque are exposed to your bloodstream. Your body treats this like an injury and forms a clot at the site. That clot can partially or completely block the artery. When blood stops flowing to a section of heart muscle, those cells begin dying within about 20 minutes, and the damage spreads the longer the blockage lasts.
Two Types of Heart Attack
Doctors classify heart attacks into two main types based on how completely the artery is blocked, which shows up as different patterns on an electrocardiogram (ECG).
A STEMI (ST-elevation myocardial infarction) is the more severe type. The artery is fully blocked in about 84% of these cases, cutting off blood flow entirely. This produces a distinct spike on the ECG and usually causes more widespread muscle damage. A NSTEMI (non-ST-elevation myocardial infarction) involves a partial blockage. Blood flow is reduced but not completely stopped in most cases. NSTEMIs can still be serious, though, because they often involve disease in multiple arteries rather than just one.
Classic Symptoms and How They Differ in Women
The textbook heart attack symptom is chest pain or pressure, often described as a heavy weight sitting on your chest. That pain can spread to your left arm, neck, jaw, or back. You may also feel short of breath, break into a cold sweat, or become nauseated.
Women, however, frequently experience something different. Chest pain may not be the most prominent symptom, or it may be absent altogether. Instead, women are more likely to notice unusual fatigue, dizziness, nausea, vomiting, shortness of breath, or pain in the back, jaw, or upper abdomen. These symptoms can come on during rest or even during sleep, making them easy to dismiss as the flu or stress. This difference is one reason heart attacks in women are more likely to be diagnosed late.
What Happens at the Hospital
If you call emergency services for a suspected heart attack, paramedics will typically give you chewable aspirin right away, usually a dose between 162 and 325 mg. Aspirin helps slow the growth of the blood clot. You may also receive nitroglycerin, a tablet or spray placed under the tongue that widens blood vessels and can relieve chest pain.
At the hospital, doctors confirm the diagnosis with an ECG and a blood test that measures troponin, a protein released by damaged heart cells. In a healthy person, troponin levels are near zero. Elevated levels confirm that heart muscle has been injured. Troponin peaks around 72 to 96 hours after the event, so doctors often test it repeatedly to track how the damage is progressing.
For a STEMI, the priority is reopening the blocked artery as fast as possible. The standard treatment is a catheter-based procedure where a thin tube is threaded through a blood vessel (usually from the wrist or groin) to the blocked artery and a small balloon is inflated to widen it. A metal stent is then placed to keep it open. Guidelines set a target of 90 minutes from hospital arrival to balloon inflation. For a NSTEMI, the timeline is less urgent, but many patients still undergo the same procedure within hours or days depending on their risk level.
What Raises Your Risk
Nearly half of Americans have at least one of the three biggest modifiable risk factors for the artery disease that leads to heart attacks: high blood pressure, unhealthy cholesterol levels, or smoking. High blood pressure is the single largest contributor, damaging artery walls over time and creating the conditions for plaque buildup. In fact, it accounts for more heart-attack-related deaths than any other changeable risk factor in the United States.
Other major factors include a sedentary lifestyle, which drives up unhealthy cholesterol levels, and a diet high in saturated fat from sources like red meat and full-fat dairy. Heavy alcohol use also raises total cholesterol. Diabetes, obesity, and a family history of early heart disease further increase risk, though those last factors are harder or impossible to change directly.
Complications After a Heart Attack
Once a heart attack damages muscle tissue, that tissue is replaced by scar tissue, which can’t contract. If enough muscle is lost, the heart becomes a weaker pump. This is how heart attacks lead to heart failure, a chronic condition where the heart can’t meet the body’s demands for blood and oxygen. Symptoms include persistent fatigue, fluid buildup, and shortness of breath during everyday activities.
The damaged area can also disrupt the heart’s electrical system, leading to abnormal heart rhythms (arrhythmias) that range from harmless palpitations to life-threatening events like ventricular fibrillation. More serious structural complications, such as a tear in the wall between the heart’s chambers or rupture of the muscle that anchors a heart valve, occur in less than 1% of heart attack patients today. Modern treatment has made these rare, but when they do happen, they carry a hospital mortality rate between 10% and 40%.
Life After a Heart Attack
Recovery starts with cardiac rehabilitation, a supervised program of exercise, education, and lifestyle coaching that has been shown to reduce both the chance of dying and the risk of another event. Most programs run 12 weeks, with sessions two or three times a week, though the benefits come from maintaining those habits permanently.
The lifestyle changes that matter most are straightforward. A Mediterranean-style diet, rich in vegetables, fruits, whole grains, fish, and olive oil while low in red meat and processed food, is the eating pattern with the strongest evidence behind it. Current guidelines recommend keeping saturated fat below 6% of daily calories and sodium below 2,300 mg per day, with an ideal target of 1,500 mg. Dietary supplements, including fish oil and omega-3 capsules, have not been shown to reduce cardiovascular events and are not recommended.
Physical activity goals after recovery are the same as for the general population: at least 150 to 300 minutes of moderate exercise per week (like brisk walking) or 75 to 150 minutes of vigorous exercise, plus muscle-strengthening activities at least two days a week. Quitting smoking, if applicable, is the single most impactful change you can make. E-cigarettes are not recommended as a first-line quitting method due to a lack of long-term safety data.
Most heart attack survivors will also take medications long-term, including a cholesterol-lowering statin and low-dose aspirin (75 to 100 mg daily). These reduce the risk of a second event significantly and are considered standard care.