Acute cardiac event is a medical emergency that affects the heart’s ability to function, often occurring suddenly and requiring immediate attention to prevent permanent damage or death.

Epidemiology

Acute cardiac events represent one of the most significant health challenges facing modern society. In the United States alone, more than 800,000 people experience a heart attack each year, making it an extremely common medical emergency^[3]. The broader category of acute coronary events affects more than 1,000,000 Americans annually, with over 400,000 deaths occurring from coronary artery disease each year^[4].

Cardiovascular diseases, which include acute cardiac events, are the leading cause of death globally. An estimated 19.8 million people died from cardiovascular diseases in 2022, representing approximately 32% of all global deaths worldwide. Of these deaths, 85% were due to heart attack and stroke^[8]. This means that nearly one out of every three deaths around the world can be traced back to problems with the heart and blood vessels.

The burden of these events falls disproportionately on certain populations. Over three quarters of cardiovascular disease deaths take place in low- and middle-income countries^[8]. The average age at first myocardial infarction (the medical term for heart attack, which refers to death of heart muscle tissue) is 65 years in men and 72 years in women^[12]. This seven-year difference reflects important variations in how heart disease affects different groups.

Between 2010 and 2030, the financial impact of cardiovascular diseases in the United States is expected to grow dramatically. Total direct medical costs are projected to triple from 273 billion to 818 billion dollars^[4]. This staggering increase reflects not only the aging population but also the rising incidence of conditions like diabetes and obesity that increase the risk of heart problems.

Causes

The underlying cause of most acute cardiac events is coronary atherosclerosis, a condition where the arteries supplying blood to the heart become narrowed or blocked. This happens when a substance called plaque—a sticky mixture of fats, cholesterol, and other materials—builds up on the inside walls of the arteries^[3]. You can think of it like pouring grease down a kitchen sink: over time, the grease accumulates and clogs the pipes, reducing water flow.

When plaque accumulates in large amounts in the blood vessels that supply the heart, the condition is called coronary artery disease^[3]. This disease is the main cause of heart attacks and is the most common cause of death in the United States^[5]. Most heart attacks happen because of a blockage in one of these blood vessels.

The process that leads to an acute cardiac event often begins with plaque deposits inside the coronary arteries breaking open or rupturing. When this happens, a blood clot forms at the site of the rupture^[6]. The clot may then block the supply of blood to the heart, triggering a heart attack. Without blood flow, the affected heart muscle begins to die. The longer the blockage remains, the more damage occurs to the heart tissue.

A less common cause of acute cardiac events is a severe spasm or sudden contraction of a coronary artery that stops blood flow to the heart muscle^[5]. In rare cases, events may be caused by coronary dissection (a tear in the artery wall), arteritis (inflammation of the arteries), thromboembolism (a blood clot traveling from elsewhere), or coronary vasospasm without obvious coronary artery disease^[4].

Risk Factors

Several health conditions, lifestyle factors, and personal characteristics can increase your risk of experiencing an acute cardiac event. About half of all Americans have at least one of three key risk factors: high blood pressure, high blood cholesterol, and smoking^[5]. These three factors play a major role in the development of heart disease.

People who are overweight, physically inactive, or have diabetes face higher risk of cardiovascular disease. High blood pressure and high cholesterol are particularly important because they directly contribute to the formation of plaque in the arteries^[15]. When blood pressure remains elevated for long periods, it damages the walls of blood vessels, making them more susceptible to plaque buildup.

Certain medical conditions significantly increase the likelihood of an acute cardiac event. Those with coronary artery disease are at particularly high risk, though many people don’t know they have it because it often doesn’t cause symptoms^[7]. Having a history of irregular heartbeats, called arrhythmias, also raises the risk. Heart conditions like cardiomyopathy (an enlarged heart) and heart failure can predispose someone to acute events^[15].

Age is an important factor that cannot be changed—risk increases as you get older^[7]. Family history also matters considerably. If your parents or siblings had heart disease, especially at a young age, your own risk is higher. Men are generally at higher risk than women, though women’s risk increases after menopause. Being Black or African American, especially when combined with conditions like diabetes, high blood pressure, heart failure, or chronic kidney disease, also increases risk^[7].

Certain malignant cancers and the drugs used to treat them can lead to blood clots, which can block blood flow to the heart and cause cardiac events^[15]. Physical stress on the body can also trigger events. Intense physical activity that causes the body to release adrenaline can trigger an acute cardiac event in people who already have heart problems^[7]. Very low blood levels of essential minerals like potassium or magnesium, major blood loss, or severe lack of oxygen can all stress the heart to the point of causing an event.

Symptoms

Acute cardiac events usually start suddenly, and recognizing the symptoms quickly can save a life. The most common symptom is chest pain or discomfort. Many people describe it as a feeling of pressure, heaviness, tightness, squeezing, or aching in the chest^[1]. This chest pain is also called angina. The discomfort can feel like uncomfortable pressure, squeezing, fullness, or pain, and it may last for more than a few minutes or go away and come back^[5].

Pain from an acute cardiac event doesn’t always stay in the chest. It often spreads to other parts of the body, including the shoulders, arms (usually the left arm, but it can affect both arms), upper belly area, back, neck, or jaw^[1]. Some people experience it as pain or discomfort in the jaw, neck, or back, or pain or discomfort in one or both arms or shoulders^[5].

Many people experiencing an acute cardiac event feel other symptoms along with or instead of chest pain. These include shortness of breath, which often comes along with chest discomfort but can also happen before chest discomfort begins^[5]. Nausea or stomach discomfort is common—some people think they’re just having indigestion or heartburn when they’re actually having a heart attack^[3].

Feeling weak, lightheaded, or faint is another warning sign. Many people break into a cold sweat^[5]. Some experience an overwhelming feeling of anxiety, similar to a panic attack, or a sensation described as “impending doom”^[3]. Trouble sleeping, heart palpitations, dizziness, or even passing out can occur.

Sometimes people have warning signs hours or even days in advance. Some experience unusual or unexplained tiredness in the days before an acute cardiac event^[5]. Others may have a racing heartbeat or feel dizzy or light-headed just before they faint^[7]. However, many acute cardiac events happen suddenly without any preceding symptoms, which is why they’re often called sudden cardiac events.

Prevention

Preventing acute cardiac events involves addressing the factors that increase risk. The most important behavioral risk factors are unhealthy diet, physical inactivity, tobacco use, and harmful use of alcohol^[8]. Making changes in these areas can significantly reduce your chances of experiencing a heart attack or other acute cardiac event.

If you smoke, quitting is one of the most important steps you can take. Smoking damages blood vessels and contributes to the buildup of plaque in arteries. The good news is that after you quit, your risk begins to decrease relatively quickly. People who are overweight or obese should work toward a healthy weight, as excess weight increases the burden on the heart and contributes to other risk factors like high blood pressure and diabetes^[6].

Regular physical activity is essential for heart health. Adults should aim for at least 150 minutes of moderate-intensity aerobic exercise each week unless a doctor advises otherwise^[6]. This could be brisk walking, swimming, cycling, or any activity that gets your heart rate up. Regular exercise helps control weight, lowers blood pressure, improves cholesterol levels, and helps manage blood sugar.

Diet plays a crucial role in prevention. A heart-healthy diet should be low in fat and high in fiber, including whole grains and at least five portions of fruits and vegetables each day^[6]. Reducing salt, sugar, and unhealthy fats helps lower blood pressure and cholesterol levels. The effects of dietary choices may show up as raised blood pressure, raised blood glucose, raised blood lipids (fats in the blood), and being overweight or obese^[8].

Moderate your alcohol consumption. Drinking too much alcohol can raise blood pressure and contribute to heart problems. If you drink, do so in moderation. Regular health screenings are also important. Get your blood pressure and cholesterol checked regularly, and if you have diabetes, work with your healthcare provider to keep your blood sugar well-controlled^[6].

Managing stress is another important aspect of prevention. Getting enough quality sleep each night helps your heart recover and function properly. Poor sleep has been linked to increased risk of heart disease. For people who already have heart disease or have had a previous cardiac event, taking prescribed medications regularly is crucial for preventing future events.

Pathophysiology

To understand what happens during an acute cardiac event, it helps to know how the heart normally works. Your heart is a muscular pump that constantly beats to circulate blood throughout your body. The heart muscle itself needs a constant supply of oxygen-rich blood to function, which it receives through the coronary arteries.

Coronary atherosclerosis develops over many years. Studies of young adults who died from non-natural causes show that coronary atherosclerosis exists in more than 80% of people, with approximately 8% already having obstructive disease^[4]. The disease often begins in childhood and adolescence with fatty streaks visible in the arteries, then progresses throughout adulthood depending on genetic and environmental factors.

When a heart attack occurs, blood flow to a part of the heart stops or becomes severely reduced. This happens because a blockage prevents blood from reaching that area. Without blood flow, the affected heart muscle doesn’t get the oxygen it needs^[1]. Heart tissue cells begin to die or become damaged. If blood flow isn’t restored quickly, a heart attack can cause permanent heart damage or death.

The blockage is usually caused by plaque buildup that ruptures, triggering the formation of a blood clot. This clot can completely block the artery, cutting off blood supply downstream. Sometimes the blockage is partial, allowing some blood to pass but not enough to meet the heart’s needs, especially during physical exertion or stress.

When part of your heart can’t pump because it’s dying from lack of blood flow, it disrupts the pumping function of your entire heart^[3]. This can reduce or completely stop blood flow to the rest of your body. Without adequate blood flow, your organs and tissues don’t receive the oxygen they need to function. Your brain is particularly vulnerable—it needs a constant supply of oxygen-rich blood to maintain consciousness and function properly.

In some cases, the heart’s electrical system is affected. Your heart has a complex electrical system that controls the rate and rhythm of your heartbeat. When this system malfunctions, it can cause irregular heartbeats or arrhythmias^[7]. Some arrhythmias can cause the heart to beat too fast, too slow, or with an irregular rhythm. The most dangerous type is ventricular fibrillation, where the heart’s lower chambers don’t beat normally but instead beat very fast and very irregularly. They can’t pump blood to the body, which causes most sudden cardiac arrests^[7].

The heart’s inability to pump effectively means that blood pressure drops and organs throughout the body begin to suffer. The kidneys, liver, brain, and other organs all depend on steady blood flow to function. When that flow is interrupted, the effects cascade through multiple body systems. This is why acute cardiac events can impact not just the heart itself but the pulmonary (lung), vascular (blood vessel), and neurological (nervous system) systems as well^[15].