A heart aneurysm is a bulge or balloon-like weak spot in the wall of the heart, most commonly in the left ventricle, the chamber responsible for pumping blood out to the rest of the body. It typically forms after a heart attack damages and weakens a section of heart muscle. Among heart attack hospitalizations, roughly 0.2% of patients develop a ventricular aneurysm, though the actual number may be higher since many cases produce no obvious symptoms.
How a Heart Aneurysm Forms
The overwhelming majority of heart aneurysms develop after a heart attack cuts off blood flow to part of the heart muscle. Without oxygen, that section of muscle dies. In the early phase, the dead tissue triggers an intense inflammatory reaction as the body attempts to clean up and repair the damage. Over the following weeks and months, the destroyed muscle is gradually replaced by scar tissue.
This scar tissue is thinner and far less elastic than healthy heart muscle. It can’t contract the way normal muscle does, so it bulges outward with each heartbeat as blood pressure pushes against it. Over time, the scar becomes a smooth, white fibrous patch. The border zone between the aneurysm and the surrounding healthy muscle develops a disorganized mix of scar and misaligned muscle fibers, which creates electrical instability in that region of the heart.
True vs. False Aneurysms
Heart aneurysms come in two distinct forms, and the difference matters because one is far more dangerous than the other.
A true aneurysm involves all layers of the heart wall. The weakened section stretches and bulges, but the wall remains intact. Blood fills the bulging sac with each heartbeat, yet the heart wall holds together. This is the more common type and usually develops gradually after a heart attack.
A false aneurysm (also called a pseudoaneurysm) is more like a contained rupture. The heart wall actually tears, and blood leaks through the break into the pericardium, the protective membrane surrounding the heart. The pericardium acts as a temporary dam, holding the blood in place. False aneurysms are considered a surgical emergency because the pericardium can only contain the leak for so long before it gives way entirely.
Symptoms to Recognize
Many heart aneurysms cause no symptoms at all, especially small ones. They’re often discovered incidentally during imaging tests done for other reasons. When symptoms do appear, they tend to reflect the heart’s declining ability to pump efficiently or the electrical problems caused by scar tissue.
Common symptoms include:
- Shortness of breath, particularly during physical activity or when lying flat, because the weakened wall reduces the heart’s pumping power
- Fatigue and weakness from reduced blood flow to the body
- Heart palpitations or irregular heartbeat, caused by the disorganized electrical signals at the border zone of the aneurysm
- Chest pain, which may feel similar to the original heart attack pain
- Swelling in the legs or ankles as the heart struggles to keep up with circulation
These symptoms often overlap with heart failure, which makes sense: a heart aneurysm is essentially a section of the heart that no longer contributes to pumping. The larger the aneurysm, the more pumping capacity is lost.
Why Blood Clots Are a Serious Risk
One of the most concerning complications is the formation of blood clots inside the aneurysm. Blood tends to pool and swirl sluggishly in the bulging sac rather than flowing smoothly through the chamber. This stagnant blood is prone to clotting.
If a clot forms on the inner wall of the aneurysm and then breaks free, it can travel through the bloodstream to the brain and cause a stroke. After a heart attack affecting the front wall of the heart, clots most commonly form in areas where the wall has become completely still or is bulging outward. The risk is highest in the weeks and months after the initial heart attack, though it persists as long as the aneurysm is present. Blood-thinning medications are often used to reduce this clot risk in patients with known aneurysms.
How Heart Aneurysms Are Treated
Treatment depends on the size of the aneurysm, how much it affects the heart’s pumping ability, and whether it’s causing symptoms or complications.
Medication-Based Management
Many patients with small, stable aneurysms are managed without surgery. The goals are to reduce the workload on the heart, prevent blood clots, and control any irregular heart rhythms. This typically involves medications that lower blood pressure, ease the heart’s pumping effort, and thin the blood. Regular imaging monitors the aneurysm’s size over time to watch for any dangerous changes.
Surgical Repair
When the aneurysm is large, causing significant heart failure symptoms, or producing dangerous arrhythmias, surgery becomes an option. The most widely used technique is called surgical ventricular reconstruction. The goal is to cut away the dead, scarred section of the heart wall and reshape the remaining ventricle back into something closer to its normal elliptical form.
The most common version of this procedure uses a patch sewn inside the ventricle to exclude the scarred area and rebuild the chamber’s shape. By restoring a more natural geometry, the heart pumps more efficiently. Surgeons often perform bypass grafting at the same time to improve blood flow to the surviving heart muscle. Long-term results are encouraging: survival rates after surgical repair have been reported at roughly 91% at five years, 81% at ten years, and 74% at fifteen years.
False aneurysms, because of their high rupture risk, almost always require urgent surgical repair regardless of size.
Living With a Heart Aneurysm
For many people, a heart aneurysm becomes a chronic condition managed alongside the broader recovery from a heart attack. The aneurysm itself doesn’t heal or shrink over time. The scar tissue is permanent. What changes is how well the rest of the heart compensates and how effectively medications control symptoms and prevent complications.
Regular follow-up imaging, usually echocardiograms, tracks the size of the aneurysm and how well the heart is pumping overall. Any new or worsening shortness of breath, swelling, chest pain, or palpitations warrants prompt evaluation, since these can signal that the aneurysm is growing, a clot has formed, or heart failure is progressing. With appropriate monitoring and treatment, many people with heart aneurysms live for decades after their diagnosis.