I haven't followed this case and trial from its beginning, so I could have missed some evidence, but initially I thought the idea of a spray tan causing an allergic reaction was so far-reaching, he had to be guilty. However, I want to talk about the issue of myocarditis, because I have personal familiarity with that condition.
Myocarditis, inflammation of the heart, can be triggered by exposure to many bacterial (common strep throat) and viral (cocksackie) causes. It can be a long-term condition, and after a single initial episode, the body's immune system may learn to attack itself again and again worsening the condition over years.
I developed heart inflammation after having rheumatic fever and have had multiple relapses after exposure to the cocksackie virus, various other viruses and even vaccinations. I have at times been very physically active and apparently healthy and able to exercise with this underlying condition, so I can tell you that it is possible to have this condition and ignore it. It is also possible to be so frightened something is horribly wrong, that you really don't want to go to the doctor, or especially as a busy wife and mother who is (mostly) asymptomatic.
When things were very bad, I also been symptomatic, very physically weak and fatigued, and also dizzy with an elevated heart rate, an irregular heartbeat, and a great deal of chest pain. I have been so dizzy I could have passed out, though I also had other symptoms of a immune system response, including severe joint pain -- though one of the first symptoms to appear was the elevated heart rate. Did she have other symptoms of a malfunctioning immune system? During these periods, in my case, it was obvious that something was wrong, which my physicians confirmed and treated with prednisone and other immunosuppresive medications. Sometimes the heart damage is only detectable during autopsy. I do believe this could be a tragic accident, if in fact she had confirmed myocarditis.
Some of the 'reaching for any excuse' such an allergic reaction to a spray tan, definately hurt the defense credibility in this case, IMO. It is always difficult to know the truth after the fact. I really feel this is a very hard case to call.