Yesterday, we stated in our blog that George Michael "may well have suffered from cardiac arrest, similar to Carrie Fisher only a few days ago, which could in the singer's case be due to underlying coronary artery disease or, of course, the use of certain drugs."
Indeed, this morning's news is now reporting the cause of death to be cardiac arrest, not heart failure (although it seems unlikely that many journalists appreciate the important differences between the two). In addition, many sources are publishing the words of the singer's boyfriend, Fadi Fawaz, who has publicly stated that George Michael was suffering with a heroine problem.
Cardiac arrest following a drug overdose is a far more plausible cause of death for a relatively young man. As explained here, heart failure is a chronic condition, with a number of symptoms which develop over a considerable length of time.