Does pericardial effusion lead to myocardial infarction or any other serious consequence?

Yes: Large pericardial effusions can compress the heart resulting in reduced cardiac output and falling blood pressure. This condition is referred to as tamponade. Pericardial effusion does not typically cause myocardial infarction.

no and yes: It does not lead to heart attack but, if it develops rapidly or is large, it can lead to cardiac tamponade, a condition that interferes with the heart's ability to fill with blood during diastole. If this condition should develop and is not treated, it leads to death.

It can: If it is very large it can lead to tamponade, which can be fatal if the fluid is not removed.

Tamponade: Can lead to cardiac tamponade, which is squeezing of the heart by too much fluid, so that the heart cannot expand and fill wth blood and so the heart cannot pump blood, which causes low blood pressure, which can cause heart attack or other serious problems ...