What increases the risk of pericardial effusion after a heart attack?

Pericardial effusion is the abnormal accumulation of fluid around the heart. It occurs commonly after a heart attack. However, it is still unclear what the factors are that cause pericardial effusion. Cardiac magnetic resonance imaging is a procedure that uses radio waves and magnets to give an image of the heart. This procedure can be used to better analyze the heart for causes of pericardial effusion. 

Patients who had a heart attack were studied. Cardiac magnetic resonance was performed immediately after the heart attack and at 3 months follow-up. Of 193 patients, 58.5% had a pericardial effusion. The average size of the pericardial effusion was 31.6 ml.  

Patients who had a pericardial effusion were 4.8% more likely to have a larger size of heart muscle death and larger volume of blood in the left side of the heart. These patients were also 9.2% more likely to have greater stress on the wall of the heart.

These patients were more likely to have a lower volume of blood pumped by the heart each beat. Pericardial effusion was also 27% more likely after damage to area of heart leading to poor blood circulation (obstruction).

26.5% of patients with pericardial effusion and 12.5% of patients who did not have pericardial effusion had heart failure during hospitalization.  

Pericardial effusion resolved within 3 months, and was not related to any heart-related events at the 1-year follow-up. 

History of smoking, high levels of fat, high blood pressure and diabetes were similar between the group of patients who had pericardial effusion and the group of patients who did not.  

The authors concluded that stress on the heart wall, size of heart damage and microvascular obstruction was associated with pericardial effusion and volume of the pericardial effusion.