Final answer:
Rheumatic fever is the autoimmune complication that occurs 2-4 weeks post-MI.
Step-by-step explanation:
The autoimmune complication that occurs 2-4 weeks post-MI is rheumatic fever. Rheumatic fever is caused by an autoimmune reaction that is triggered by an infection with Streptococcus pyogenes, the bacterium that causes strep throat. Antibodies or T cells that react with the heart muscle, which has a similar structure to the surface of S. pyogenes, can damage the heart muscle with autoimmune attacks.