What is the most common complication of early myocardial infarction?

Arrhythmia: The most common early complication of myocardial infarction is arrhythmia typically ventricular fibrillation. If this occurs in the hospital, it responds promptly to cardioversion. If it occurs outside the hospital it can result in sudden death. The highest period of risk occurs in the first 48 hours.

Heart failure: The most common complication is arrhythmia which can occur very early in mi. If it's ventricular fibrillation as it tends to be in about 50% of cases, the result is sudden death. Heart block and atrial fibrillation also occur. Other common complications are recurrent pain and congestive heart failure. Less common is thromboembolism (systemic and pulmonary) causing stroke or pe and pericarditis.