A heart scar on a cardiac scan usually means that an area of heart muscle has been damaged and replaced by fibrous tissue, which does not squeeze like healthy muscle. A scan finding does not, by itself, show what caused the damage or how much it affects the heart. The meaning depends on the scan type, the exact report, symptoms, and overall heart function.
What does a heart scar mean on a scan?
A heart scar is an area of tissue that has changed after injury to the heart muscle. Doctors may also call this change fibrosis, which means that fibrous, scar-like tissue has developed in place of some healthy muscle tissue.
Healthy heart muscle contracts with each heartbeat to help pump blood around the body. Scar tissue does not contract in the same way. If a substantial area is affected, or if the scar is in an important location, it may reduce the heart's pumping ability or contribute to abnormal heart rhythms. The effect depends on the amount and location of the scarring, as well as how well the remaining heart muscle works.
According to the American Heart Association, heart muscle damaged during a heart attack heals by forming scar tissue. However, a finding described as a heart scar does not automatically mean that you had a recognized heart attack. Other types of heart muscle injury can also leave scar tissue.
What can cause a heart scar?
A scan may reveal scarring from an older injury, sometimes long after the original event. Possible explanations include:
- A previous heart attack: When blood flow to part of the heart muscle is severely reduced or blocked, the affected tissue can be permanently damaged. The resulting scar may remain visible long after the event. Some heart attacks cause symptoms that are mild or go unnoticed at the time.
- Previous inflammation of the heart muscle: Myocarditis is inflammation of the heart muscle, sometimes related to an infection or another inflammatory process. In some cases, injury from myocarditis leaves areas of scar tissue.
- Cardiomyopathy: This term describes diseases that affect the heart muscle. Some forms can be associated with scar tissue, changes in the size or thickness of the heart, or reduced pumping function.
- Previous heart procedures: Certain procedures, such as catheter ablation used to treat abnormal heart rhythms, deliberately create small areas of scar tissue. If you have had such a procedure, this history may help explain a finding.
The American Heart Association's information on cardiac MRI explains that this scan can help identify tissue damage from a heart attack, inflammation of the heart muscle, and several types of heart muscle disease. Doctors interpret these findings alongside your medical history and other test results rather than using the word “scar” alone to determine the cause.
Which cardiac scans can detect a heart scar?
The type of scan matters because different tests show different aspects of the heart. A report mentioning a possible scar may have a different meaning depending on whether the test examined heart muscle tissue, blood flow, the heart's movement, or its structure.
Cardiac MRI
Cardiac magnetic resonance imaging (MRI) uses a strong magnetic field and radio waves to create detailed pictures of the heart. When appropriate, a contrast agent called gadolinium is given through a vein to help distinguish different types of heart tissue. Certain patterns of contrast uptake, often described as late gadolinium enhancement, can help identify areas of damage or scarring.
The location and pattern of these changes can provide clues about the underlying cause. For example, a pattern associated with a previous heart attack may differ from one associated with a non-heart-attack-related heart muscle condition. An MRI report must still be interpreted in the context of the person's history and other findings.
Cardiac PET scan
A cardiac positron emission tomography (PET) scan uses a small amount of a radioactive tracer to provide information about how heart tissue functions. Depending on the tracer and the purpose of the examination, PET imaging can help identify damaged heart muscle and areas of scar tissue. It may also help assess blood flow and whether heart muscle is receiving enough blood.
Echocardiogram and cardiac CT
An echocardiogram uses ultrasound to show the heart's structure and movement. It helps assess how well the heart chambers contract and pump blood. Abnormal movement of part of the heart wall may suggest previous injury, but an echocardiogram does not characterize scar tissue in the same way as a cardiac MRI.
A cardiac CT scan produces detailed images of the heart and surrounding structures. It is often used to assess coronary arteries or structural problems. Some CT examinations can provide information about heart muscle damage, but the ability to identify and characterize a scar depends on the particular type of scan and the imaging technique used.
Cleveland Clinic's guide to cardiac imaging describes how MRI, PET, CT, and ultrasound provide different information about the heart. If your report mentions a scar, ask which finding supports that description and whether the test adequately answers the clinical question.
Is a heart scar dangerous?
A heart scar is not automatically a sign of a medical emergency, but it should not be dismissed without understanding its significance. Some people have a small area of scarring and maintain good overall heart function. In other cases, more extensive scarring may reduce the heart's ability to pump blood or increase the risk of abnormal electrical activity in the heart.
Doctors consider several features when assessing the potential importance of a scar:
- Location: Where the scar is located can affect how it influences the heart's contraction or electrical signals.
- Extent: The amount of affected tissue helps determine how much healthy muscle may have been replaced.
- Pumping function: The heart's ejection fraction, which is the percentage of blood pumped out of the left ventricle with each contraction, is one measure of how well the heart is working.
- Heart rhythm: Scarring can sometimes provide a pathway for abnormal electrical signals, making the history of palpitations or rhythm problems relevant.
- Underlying cause: An old, healed injury has different implications from a condition involving ongoing inflammation, reduced blood supply, or another active heart problem.
The National Library of Medicine's MedlinePlus information on cardiomyopathy notes that some people with heart muscle disease remain well, while others develop complications such as abnormal heart rhythms or heart failure. This is why a scan finding must be interpreted alongside the heart's overall function and the condition that may have caused it.
Can a heart scar be found when you have no symptoms?
Yes. A scan may show evidence of an older injury even when a person does not remember having a heart problem. For example, some heart attacks occur with mild, unusual, or unrecognized symptoms. The resulting scar may only be discovered later when imaging is performed for another reason.
On the other hand, some people with a heart scar may notice symptoms such as breathlessness during activity, unusual tiredness, reduced exercise tolerance, or a sensation of a racing or irregular heartbeat. These experiences can have many causes and do not, by themselves, establish that a heart scar is present or explain how significant one might be.
According to the American Heart Association's guidance on heart attack warning signs, chest discomfort and shortness of breath can be signs of an acute heart problem. New chest pressure or pain, sudden or severe breathlessness, or discomfort accompanied by sweating, nausea, or pain spreading to the arm, back, neck, or jaw requires urgent medical assessment. Do not wait for a routine appointment if these symptoms occur.
What happens after a scan shows a heart scar?
The next step is to establish what the scan finding means in your particular situation. Your doctor or cardiologist will review the full report, why the scan was ordered, your medical history, any symptoms, and the results of previous tests. A brief phrase in a report may not include all the information needed to make a clinical decision.
Depending on the findings, the assessment may include:
- Reviewing the full imaging report: The doctor may clarify the scar's location, extent, and pattern, and whether the radiologist considers the finding definite or uncertain.
- Checking heart function: An echocardiogram or information already available from the cardiac MRI may help show whether the heart is pumping normally.
- Assessing heart rhythm: An electrocardiogram (ECG) records the heart's electrical activity. Longer monitoring may be considered when symptoms or previous findings suggest an intermittent rhythm problem.
- Investigating the possible cause: Depending on the situation, further blood tests or imaging may be useful to assess a suspected heart attack, inflammation, cardiomyopathy, or another condition.
Not everyone needs every test. The choice depends on what is already known, whether symptoms are present, and whether additional information would change care.
Can a heart scar be treated or reversed?
Established scar tissue represents a lasting change in the heart muscle and generally does not return to normal contracting muscle. However, finding a scar does not mean that nothing can be done. Management focuses on the underlying condition, the heart's performance, and any complications or future risks identified during the assessment.
For example, if the evidence points to coronary artery disease or a previous heart attack, care may focus on reducing the risk of further heart damage. If a person has reduced pumping function or an abnormal heart rhythm, treatment may be directed at those problems. When inflammation or another active condition is suspected, the appropriate plan depends on identifying and treating that condition.
The presence of scar tissue alone does not determine whether someone needs medication, a procedure, or ongoing monitoring. Those decisions depend on the complete clinical picture. Do not start, stop, or change heart medicines solely because a scan report uses the word “scar.” Discuss the result with the healthcare professional responsible for your care.
What should you ask your doctor about the scan result?
If your report mentions a heart scar, these questions can help you understand what it means and what to do next:
- Does the scan show definite scar tissue, or is the finding uncertain?
- Where is the scar, and how much heart muscle does it affect?
- Does the pattern suggest a previous heart attack, inflammation, or another cause?
- Is my heart pumping normally, and is there any concern about abnormal heart rhythms?
- Do I need another test, treatment, or follow-up appointment?
Bring the complete scan report and, if available, earlier cardiac imaging results to the appointment. Comparing current and previous tests may help clarify whether the finding is longstanding and whether anything has changed.
Overall, a heart scar on a cardiac scan is evidence of a change in heart tissue, but its significance varies. The most useful interpretation combines the exact imaging finding with the possible cause, the heart's pumping and electrical function, and the person's symptoms and medical history.