Acute cardiac event – Diagnostics – Overview of Information and Clinical Research

When your heart suddenly doesn’t get enough blood, every minute counts. Knowing what tests doctors use to diagnose an acute cardiac event can help you understand what happens when you or someone you love faces this medical emergency, and why acting quickly makes all the difference between life and lasting damage.

Introduction: Who Should Undergo Diagnostics

An acute cardiac event is an umbrella term that describes sudden, serious problems with your heart. This includes conditions like heart attacks (also called myocardial infarction) and unstable angina, where blood flow to your heart is suddenly reduced or completely blocked. These events happen when something interrupts your heart’s function or blood flow, and they can become life-threatening within minutes if not treated promptly.^[1]^[3]

You should seek diagnostic testing immediately if you experience certain warning signs. The most common symptom is chest pain or discomfort that feels like pressure, squeezing, heaviness, tightness, or burning. This pain may spread from your chest to your arms (usually the left arm, but it can affect both), shoulders, neck, jaw, back, or upper belly area. Many people mistake this feeling for indigestion or heartburn, which can be dangerous because it delays getting help.^[1]^[3]

Other symptoms that should prompt you to seek immediate medical attention include shortness of breath (which can happen with or before chest pain), sudden nausea or vomiting, cold sweats, feeling lightheaded or dizzy, heart palpitations, fatigue, and an overwhelming feeling of anxiety or “impending doom.”^[3]^[5]

⚠️ Important

Women often experience different symptoms than men. While men typically have chest pain, women are more likely to have shortness of breath, fatigue, insomnia that started before the heart attack, nausea and vomiting, or pain in their back, shoulders, neck, arms, or abdomen without obvious chest pain. Some people may only experience minor pain similar to indigestion, which makes it easy to dismiss the warning signs.^[3]^[6]

It’s critical to understand that acute cardiac events are medical emergencies. If you think you or someone else might be having a heart attack or any acute cardiac event, call emergency services (911 in the United States) immediately. Do not drive yourself to the hospital, as ambulances are equipped with life-saving medical equipment and staffed by trained paramedics who can provide essential care on the way. Even a delay of just a few minutes can result in permanent heart damage or death.^[3]^[5]

Certain people are at higher risk for acute cardiac events and should be especially alert to symptoms. If you have coronary artery disease (a condition where the major blood vessels supplying your heart become clogged with fatty deposits), high blood pressure, high cholesterol, diabetes, or a family history of heart disease, your risk increases. Smoking, being overweight or obese, living an inactive lifestyle, and experiencing high levels of stress also raise your chances of having an acute cardiac event.^[5]

Classic Diagnostic Methods

When you arrive at the hospital with suspected acute cardiac event symptoms, healthcare providers will immediately begin diagnostic testing. The goal is to quickly determine whether you are having a heart attack or another serious heart problem, and to figure out the best treatment to restore blood flow to your heart as soon as possible.^[9]

The first test you’ll typically receive is an electrocardiogram, usually called an ECG or EKG. This test records the electrical signals traveling through your heart. During the test, medical staff attach small sticky patches called electrodes to your chest and sometimes to your arms and legs. These electrodes detect your heart’s electrical activity and display it as waves on a monitor or print it on paper. An ECG can show whether you are currently having a heart attack or have had one in the past. It’s painless, quick, and provides crucial information within minutes.^[9]

The ECG is particularly important because it helps doctors distinguish between different types of acute cardiac events. If the ECG shows a specific pattern called ST elevation, it indicates a STEMI (ST elevation myocardial infarction), which is a severe type of heart attack that requires immediate emergency treatment to unblock your coronary arteries. If the ECG doesn’t show ST elevation but you have other signs of a heart problem, you may have NSTE-ACS (non-ST elevation acute coronary syndrome), which includes unstable angina or another type of heart attack.^[1]^[9]

Blood tests are another essential diagnostic tool for acute cardiac events. When your heart muscle is damaged during a heart attack, certain proteins slowly leak into your bloodstream. These proteins are called cardiac markers or cardiac enzymes. By testing your blood for these markers, doctors can confirm whether a heart attack has occurred and assess how much damage has been done to your heart muscle.^[9]

One of the most important cardiac markers is troponin. When heart cells are injured or die, they release troponin into the blood. Elevated troponin levels are a strong indicator of heart damage. Blood tests for troponin can be repeated over several hours to see if levels are rising, which helps doctors understand the timing and severity of the heart attack. Other proteins that may be measured include creatine kinase (CK) and lactate dehydrogenase (LDH).^[9]

Your blood pressure, pulse, and temperature will also be checked as part of the initial assessment. These vital signs help doctors understand how well your heart is pumping blood and whether your body is under stress. Additionally, healthcare providers will ask about your symptoms, medical history, current medications, and any risk factors you have for heart disease.^[9]

A chest X-ray is often performed to examine the condition and size of your heart and lungs. This imaging test can show whether your heart is enlarged or if there is fluid in your lungs, which might indicate heart failure or other complications. A chest X-ray uses a small amount of radiation to create pictures of the structures inside your chest.^[9]

An echocardiogram uses sound waves (ultrasound) to create moving images of your heart. This test shows how blood moves through your heart and heart valves. It can help identify whether an area of your heart has been damaged during a heart attack and assess how well your heart is pumping. The test is painless and doesn’t involve radiation.^[9]

For many patients, doctors will perform a coronary catheterization, also called an angiogram. During this procedure, a healthcare provider inserts a long, thin tube (catheter) into an artery, usually in your leg or arm, and guides it to your heart using X-ray imaging. Once the catheter reaches your heart’s arteries, a special dye is injected through it. This dye makes your arteries show up clearly on X-ray images, allowing doctors to see exactly where blockages are located and how severe they are. This information is critical for deciding the best treatment approach.^[9]

In some situations, doctors may use advanced imaging tests like cardiac CT (computed tomography) or cardiac MRI (magnetic resonance imaging). These tests create detailed cross-sectional images of your heart and chest. CT scans use X-rays to create images, while MRI uses magnetic fields and radio waves. Both can provide valuable information about the structure of your heart, blood flow, and any damage that has occurred.^[9]

Diagnostics for Clinical Trial Qualification

When patients with acute cardiac events are considered for participation in clinical trials, they typically undergo the same standard diagnostic tests described above. Clinical trials are research studies that test new treatments, medications, or medical devices to see if they are safe and effective. To qualify for these trials, patients must meet specific criteria that are determined through careful diagnostic testing.^[12]

The diagnostic criteria for clinical trial enrollment usually include a confirmed diagnosis of acute cardiac event based on ECG findings and blood test results showing elevated cardiac markers like troponin. Researchers need to document exactly what type of acute cardiac event a patient has experienced—whether it’s a STEMI, NSTEMI, or unstable angina—because different trials may focus on different conditions or patient populations.^[12]

Trial protocols often specify timing requirements for diagnosis. For example, some trials may only include patients whose symptoms began within a certain number of hours before hospital arrival. This is why accurate documentation of when symptoms started is so important. Healthcare providers will carefully record the time you first noticed symptoms and when you arrived at the hospital.^[12]

Blood tests measuring cardiac markers are essential for trial qualification. Many clinical trials require specific levels of troponin or other cardiac enzymes to confirm that significant heart damage has occurred. Some trials may also require measurement of other blood values, such as kidney function tests (creatinine and blood urea nitrogen) or blood cell counts, to ensure patients don’t have other conditions that might interfere with the study treatment or put them at increased risk.^[12]

Coronary angiography findings are often used as criteria for clinical trial enrollment. Researchers may need to know which coronary arteries are blocked, how severe the blockages are, and whether patients have single-vessel or multi-vessel disease. This information comes from the catheterization procedure and helps researchers select appropriate patients for trials testing specific interventions.^[12]

Echocardiogram results may also be important for trial qualification, particularly measurements of left ventricular ejection fraction (LVEF), which indicates how well the left side of your heart is pumping blood. Some trials specifically enroll patients with reduced ejection fraction (indicating weakened heart function), while others may focus on patients with preserved heart function. This measurement helps researchers understand whether a new treatment works better for certain groups of patients.^[12]

⚠️ Important

Clinical trials may exclude patients with certain other medical conditions or complications. Diagnostic tests are used to screen for these exclusion criteria. For example, patients with severe kidney disease, recent major bleeding, very high or very low blood pressure, or certain other heart conditions might not be eligible for specific trials. These restrictions exist to protect patient safety and ensure the trial results are scientifically valid.

Additional diagnostic tests may be required depending on the specific clinical trial. Some studies might require baseline imaging with CT or MRI to document the extent of heart damage before starting experimental treatment. Others might need special blood tests to measure inflammation markers, cholesterol levels, blood sugar control (measured by hemoglobin A1c in diabetic patients), or genetic markers that could affect how patients respond to treatment.^[12]

It’s important to understand that participating in a clinical trial is completely voluntary. If you’re approached about joining a trial after an acute cardiac event, you’ll receive detailed information about the study, including what additional tests might be required, what the experimental treatment involves, potential risks and benefits, and alternatives to participation. You have the right to ask questions, discuss the trial with your family, and decline participation without affecting your standard medical care.

Prognosis and Survival Rate

Prognosis

The outlook after an acute cardiac event depends on several factors, including how quickly you received treatment, the extent of damage to your heart muscle, your age, and your overall health. The more time that passes without treatment to restore blood flow, the greater the damage to your heart muscle. This is why immediate emergency care is so critical.^[5]^[6]

If you survive the initial acute cardiac event, your heart may be damaged, which could affect its rhythm and ability to pump blood to the rest of your body. You may be at risk for another heart attack or other complications such as stroke, kidney disorders, heart failure, and abnormal heart rhythms (arrhythmias). Some serious complications can include severe irregular heartbeats that can cause the heart to stop, heart rupture where the heart’s muscles or valves split apart, or cardiogenic shock where the heart’s muscles are so damaged they can no longer supply enough blood to maintain body functions.^[5]^[6]

However, many people do survive acute cardiac events when they receive prompt treatment, and the outlook often depends on factors like your age, the severity of the heart attack, how quickly treatment began, and your general health. Younger patients without other serious medical conditions typically have better outcomes than older patients with multiple health problems.^[6]

Your prognosis can be significantly improved through proper follow-up care after an acute cardiac event. This includes taking prescribed medications regularly (such as aspirin, blood pressure medications, cholesterol-lowering drugs called statins, and other heart medications), participating in cardiac rehabilitation programs, making lifestyle changes like quitting smoking, eating a healthier diet, exercising regularly, losing weight if needed, and managing conditions like diabetes and high blood pressure.^[17]^[21]

Survival Rate

Every year in the United States, more than 800,000 people have a heart attack. Cardiovascular diseases, which include acute cardiac events, are the leading cause of death globally. An estimated 19.8 million people died from cardiovascular diseases worldwide in 2022, representing approximately 32% of all global deaths, with 85% of these deaths due to heart attack and stroke.^[3]^[8]

More than 400,000 Americans die annually from coronary artery disease, and more than 1,000,000 suffer acute coronary events each year. However, it’s important to understand that survival rates have improved significantly over recent decades thanks to advances in emergency treatment, particularly procedures that quickly restore blood flow to the heart and medications that prevent blood clots.^[4]

The chances of surviving an acute cardiac event are much better when treatment begins immediately. Some people die suddenly from complications of a heart attack before reaching the hospital or within the first month after a heart attack. However, when patients receive rapid treatment with procedures like primary percutaneous coronary intervention (PCI) or appropriate medications, combined with proper medical management, their short-term and long-term outcomes can be significantly improved.^[6]^[12]

For sudden cardiac arrest—which is different from a heart attack but can occur during or after an acute cardiac event—more than 356,000 Americans each year experience cardiac arrest outside of a hospital. Survival depends heavily on immediate bystander CPR and defibrillation. Quick treatment with CPR and a defibrillator may be lifesaving and provides the best chances of survival with good health outcomes.^[7]^[22]

#1 Clinical Trials Search in Europe