What is the Difference Between Myxoma and Thrombus?

Myxoma and thrombus are two distinct types of cardiac masses that can form in the heart's chambers. They have different characteristics and require different treatment approaches. Here are the key differences between myxoma and thrombus:

1. Origin: Myxomas most often originate in the fossa ovalis, whereas thrombi typically originate in the left atrial appendage.
2. Size: Myxomas are generally larger than thrombi and are frequently found in the left atrium.
3. Mobility: Myxomas are more mobile than thrombi, which may be attached to the heart wall.
4. Shape: Myxomas usually have a smooth, round shape, while thrombi may have a more irregular shape.
5. Prolapse: The detachment of a portion of the mass from the main body is more common in myxomas than in thrombi.
6. Treatment: Myxomas require surgical resection, while thrombi can often be managed with anticoagulation therapy.

Differentiating between myxomas and thrombi is crucial due to the distinct treatment approaches and the risk of embolization in both cases. Imaging techniques such as computed tomography (CT) and echocardiography, including three-dimensional echocardiography, can be used to differentiate between myxomas and thrombi. In some cases, atrial thrombi may have a stalk and can be misdiagnosed as myxomas.

Comparative Table: Myxoma vs Thrombus

Here is a table comparing the differences between myxomas and thrombi:

Myxomas are larger than thrombi, with an average size of 33 ± 16 mm compared to 21 ± 7 mm for thrombi. They can be found in both the left and right atria, and their signal on T1 and T2 weighted sequences varies. Myxomas may enhance on first pass perfusion, and they often show heterogeneous enhancement on late gadolinium enhancement (LGE). In terms of echocardiographic features, myxomas tend to be more mobile, have a narrower base of attachment to the wall of the cardiac chamber, and arise at different locations. On the other hand, thrombi have a uniformly low signal on T1 and T2 weighted sequences, do not typically enhance on first pass perfusion, and appear dark on LGE. Thrombi and myxomas have no specific differences in their echocardiographic appearance.