His cardiomyopathy is not caused by his Diet,look at this ...

Cardiomyopathy

In 2000, Dr. Atkins developed cardiomyopathy, an incurable heart condition which has quite a few different causes. His was thought to be from a viral illness, and his physician stated at the time that there was no evidence that his diet contributed to the condition. His coronary arteries were reported to have been checked at that time and found to be free of blockages.

Cardiomyopathy makes it more likely that a person will have a cardiac arrest (heart stopping), which happened to him two years later. Again, the cardiac arrest was not thought to be diet related. His cardiologist stated that (other than the cardiomyopathy), Atkins had "an extraordinarily healthy cardiovascular system". News report about that incident.