I've begun to notice that the number one killer of soldiers on my Island is rebel stress. After every rebel fight that occurs, I have begun to notice that my soldiers tend to have heart attacks and die, after killing or chasing off the rebels. ...
We now know that the 'cause of death'
heart attack is only a random selection from a list and has no actual connection with the cause of death. I speculate that army members who die shortly after a rebel attack die either because they reach their normal, predesignated death date or because they do not have time to get home to recharge their rest needs meter and die from overwork.
http://www.the-nextlevel.com/tropico/cafe/index.php?topic=6599.0