That in turn can cause seizures making the patient pass out.
Worth pointing out a couple of things about Kawasaki syndrome:
Seizures are very uncommon. Maybe during the acute episode during a high fever; fevers themselves can cause seizures sometimes. But Kawasaki syndrome is rarely a cause of encephalitis (swelling of the brain) or residual brain problems.
Symptoms of acute attack are a high fever above 101 for more than five days, severe redness in the eyes, a rash on the stomach and chest, red, cracked, dry lips, swollen tongue, sore throat and swollen lymph nodes.
It occurs mostly in winter and spring, it's usually among toddlers and rarely in children under three months or in adults.
It is rarely fatal. Most children tend to recover. Death may occur if the cardiac complication is unrecognized.
The key word is rare, it is remotely possible that Jett was suffering from an acute attack of the syndrome, resulting in a fever which resulted in a seizure. OK, he's older than the usual victims and the autopsy didn't mention any of the trace symptoms and even when suffering an acute attack seizures are extremely rare but possible. One has to ask why wasn't the fever spotted in this case.