Fascinating study of the impact of aerobic fitness on surviving a first heart attack. Notice that the people with a higher risk of death were not obese.

The 28-day EM rate was 10.6% overall, and 13.9%, 10.7%, 6.9%, and 6.0% in the less than 6, 6 to 9, 10 to 11, and 12 or more METs categories, respectively (P<.001). Patients who died were more likely to be older, be less fit, be nonobese, have treated hypertension, and have a longer duration from baseline to incident MI (P<.05).

Source: High Exercise Capacity Attenuates the Risk of Early Mortality After a First Myocardial Infarction – Mayo Clinic Proceedings