A heart aneurysm is a bulge or ballooning in the wall of the heart, most commonly in the left ventricle, the chamber responsible for pumping blood to the rest of your body. It typically forms after a heart attack damages and weakens the muscle, leaving behind a thin, scarred area that stretches outward under pressure. While once seen in up to 19% of patients after a major heart attack, improved treatments have driven the rate down dramatically, with modern U.S. data reporting it in roughly 0.2% of acute heart attack admissions.
How a Heart Aneurysm Forms
About 90% of cardiac aneurysms develop after a full-thickness heart attack, one that damages the muscle all the way through the wall. When a blocked artery cuts off blood supply to a section of the heart, that tissue dies and is gradually replaced by scar tissue. Scar tissue can’t contract the way healthy muscle does. Over time, the pressure of blood pumping through the heart pushes that weakened patch outward, creating a pouch or bulge that moves in the opposite direction of a normal heartbeat.
The location of the aneurysm depends on which artery was blocked. Most form on the front wall, side wall, or the tip (apex) of the left ventricle, since these areas are supplied by the artery most commonly involved in heart attacks. Less often, aneurysms can develop in the right ventricle, in the thin wall between the upper chambers, or even in the coronary arteries themselves.
True Aneurysm vs. Pseudoaneurysm
Not every bulge in the heart wall is the same. The distinction between a true aneurysm and a pseudoaneurysm matters because their risks and treatment paths are very different.
A true aneurysm still contains elements of the original heart muscle, even though that muscle is thinned and scarred. It has a wide opening where it connects to the rest of the heart wall, with a smooth, gradual transition from normal tissue to the weakened area. True aneurysms grow slowly and, while they cause problems over time, they rarely rupture.
A pseudoaneurysm is more dangerous. It forms when the heart wall actually tears open and the rupture is contained only by the surrounding sac (the pericardium) or a blood clot that seals the hole. The connection between the pseudoaneurysm and the heart chamber is narrow, like a bottleneck. Because the wall of a pseudoaneurysm contains no muscle at all, just fibrous tissue and pericardium, it carries a high risk of enlarging rapidly and rupturing. Pseudoaneurysms typically require urgent surgical repair, while true aneurysms can often be managed more conservatively.
Symptoms to Watch For
Many heart aneurysms produce no obvious symptoms on their own, especially small ones. They’re frequently discovered during imaging done for another reason, such as a follow-up echocardiogram after a heart attack. When symptoms do appear, they tend to reflect the complications the aneurysm is causing rather than the bulge itself.
The most common signs include shortness of breath, fatigue, and swelling in the legs or ankles, all of which point to the heart struggling to pump efficiently. Some people experience chest pain or palpitations (a fluttering or racing sensation). In severe cases, the first sign of a problem is a stroke or other event caused by a blood clot that formed inside the aneurysm and traveled to another part of the body.
Why Heart Aneurysms Are Dangerous
The bulging wall of an aneurysm doesn’t pump blood. Instead, it stretches outward when the rest of the heart contracts, effectively stealing pumping force. This forces the remaining healthy muscle to work harder, which can gradually lead to heart failure.
Blood Clots and Stroke
Blood inside the aneurysm pouch tends to pool and swirl slowly rather than flowing through normally. That stagnant blood is prone to clotting. After a heart attack involving the front wall of the heart, clots form in the damaged area in anywhere from 4% to 39% of cases, depending on the severity and how quickly treatment was given. Once a clot forms, it can break loose and travel to the brain, causing a stroke, or to other organs. The risk is substantial: having a clot in the left ventricle increases the chance of an embolic event by roughly 5.5 times. Left untreated, the annual rate of stroke or other embolization is estimated at 10% to 15%.
Clots that protrude into the chamber or are mobile pose the greatest danger. Even flat clots lining the aneurysm wall (called mural thrombi) cause up to 40% of clot-related events in these patients.
Abnormal Heart Rhythms
The scar tissue bordering an aneurysm can disrupt the heart’s electrical system. Normal electrical signals may loop around or through the scarred area unpredictably, triggering arrhythmias that range from extra beats to dangerous rhythms originating in the ventricles. These rhythm disturbances can cause fainting, cardiac arrest, or sudden death in severe cases.
How It’s Diagnosed
An echocardiogram, an ultrasound of the heart, is the most common first step. It can show the bulge in the heart wall, measure how well the heart is pumping, and detect blood clots inside the chamber. Doctors look for a section of wall that moves abnormally during each heartbeat, specifically an area that bulges outward when it should be contracting inward.
When more detail is needed, cardiac MRI provides a clearer picture of the scar tissue, the exact size of the aneurysm, and whether a clot is present. CT scans with heart-rate-synchronized timing can also produce precise measurements and are especially useful for distinguishing a true aneurysm from a pseudoaneurysm based on the shape of the opening. In a true aneurysm, the opening is nearly as wide as the bulge itself (a ratio close to 1.0). In a pseudoaneurysm, the opening is much narrower relative to the sac (a ratio of 0.25 to 0.5).
Treatment: Medication vs. Surgery
The approach depends on the size of the aneurysm, how well the heart is functioning, whether complications have developed, and whether it’s a true aneurysm or pseudoaneurysm.
Medical Management
Many people with a stable, true ventricular aneurysm are managed with medications alone. The goals are to reduce the workload on the heart, prevent clots, and slow further deterioration. Common medications include blood pressure drugs that lower the stress on the weakened wall, blood thinners or aspirin to reduce clot formation, and cholesterol-lowering drugs to protect the coronary arteries from further damage. Blood pressure medications that block certain hormones can help control symptoms and slow the decline in heart function, though their effect on long-term survival in this specific situation isn’t fully established.
Regular imaging follow-ups are part of the plan, tracking the aneurysm’s size and watching for new clots or worsening heart function.
Surgical Repair
Surgery becomes the recommended option when medications can’t control the problems an aneurysm is causing. The clearest reasons for operating include heart failure that doesn’t respond to medication, dangerous ventricular arrhythmias, recurrent blood clots traveling from the heart, or severe chest pain. The procedure, called an aneurysmectomy, removes the dead, scarred tissue and reconstructs the ventricle to restore a more normal shape and pumping ability.
A reduced pumping fraction alone doesn’t rule out surgery. In fact, symptomatic patients with large aneurysms tend to have a short life expectancy without an operation. Whether surgery benefits patients who have no symptoms remains an open question, and no controlled trials have directly compared surgical repair to modern medical therapy in that group.
Pseudoaneurysms are treated differently. Because of their high risk of rupture, surgical repair is typically urgent regardless of symptoms. Patients with pseudoaneurysms who don’t undergo surgery face significantly higher mortality rates.
Living With a Heart Aneurysm
For most people, a heart aneurysm is a chronic condition managed alongside the broader recovery from a heart attack. You’ll likely take several medications long-term, have periodic echocardiograms or MRIs, and work with a cardiologist to manage blood pressure and heart failure symptoms. Cardiac rehabilitation, a supervised exercise and education program, can help strengthen the remaining healthy heart muscle and improve quality of life. The key is catching complications early, particularly clots and rhythm problems, since both are treatable when identified promptly.