UPDATE: Following Chad Schieber's death in the October Chicago Marathon, another runner has died during a marathon. This time, it was Ryan Shay, one of the elite runners in the USA Olympic Trials in New York.
You can read about this death and some of the POSSIBLE causes (the autopsy has not been performed yet) here.
Autopsy result on Chad Schieber
The medical examiner's office has announced the results of the autopsy performed on Chad Schieber, who died during Sunday's Chicago Marathon. Schieber had a heart condition known as mitral valve prolapse and did not die as a result of the oppressive heat, as had been widely speculated.
Schieber, a 35-year old policeman from Michigan, collapsed at the 18 mile mark of the Chicago Marathon, and was later pronounced dead. This tragic event, together with approximately 300 other medical cases, prompted the race organizers to take the unprecedented step of shutting the course down after about 4 hours of running.
In the aftermath of the race, many have expressed opinions about whether this was the right decision. What is clear is that the race exerted a massive toll on those taking part. In a post earlier today, we looked at some of the science and physiology behind what is obviously a highly topical issue. To date, the prevalent theory for what happened to those 300 runners is that they overheated. This point is debatable, and we earlier made the point, which we emphasize again here, that the reactions to this race must be tempered by the knowledge that true heatsroke is incredibly rare, and there are other possibilities, also related to the heat, that could explain the high attrition rate.
In order for a runner to develop heat stroke, they either have to have some sort of underlying pathology or disease which compromises their ability to lose heat, or they have to run at speeds that are impossible. We explained, for example, that a 100kg man running at 5min/km (3:30 marathon pace) would be able to run for 25 hours before his temperature reached levels that were anywhere near dangerous!
Given this scenario, we emphasized that of those 300 people who required medical treatment, only a tiny percentage (1 or 2) actually over-heated. They FELT HOT, yes, but they were not hyperthermic. And that is a critical difference.
The heart condition - mitral valve prolapse
The autopsy found that Schieber had a condition known as mitral valve prolapse. This condition is actually one of the more common heart disorders, and statistics have reported that it occurs in approximately 2% of the US adult population.
Very briefly, what happens is that the mitral valve, which the valve in the heart that separates the left atrium from the left ventricle, fails to close properly when the heart contracts. Normally, this valve closes to seal off the left ventricle, which is the chamber of the heart responsible for pumping blood to the body. When it fails to close fully, it can lead to blood being forced back into the left atrium, which is called mitral regurgitation.
Now, as mentioned, mitral valve prolapse is quite common - 2%, if the statistics are to be believed. Given that there were 35,000 runners in the Chicago Marathon, and assuming that this population was representative, one would expect there to be 700 people with this condition in the race! The critical point is that mitral valve prolapse is usually harmless, and only in very rare cases, does it lead to sudden death in athletes.
In those cases, the most common cause of death is a fatal arrhythmia associated with the mitral valve prolapse. An arrhythmia, or irregular heart rhythm, is a potentially fatal condition, though it too may be quite harmless, but bothersome (skipped beats). But when the arrhythmia affects the ventricles, what starts to happen is that they 'flutter' and the heart fails to pump blood as it normally does. The defibrillator pads you often see overused in movies are used to correct this life-threatening situation.
Now, the really tricky thing is that it's very difficult to detect an arrhythmia after death, and so the autopsies often leave one wondering. Even in the case of mitral valve prolapse, it's not 100% conclusively known that the arrhythmia is related to the valve problem, which obviously complicates examinations.
Not a heat related death
However, what is known is that Schieber's death was not related to the heat. This would presumably have been diagnosed by measuring body temperature, something which is certainly not done often enough. It is for this reason that "Heatstroke" is so commonly misdiagnosed - unless a measure of body temperature is obtained, heatstroke cannot be a firm diagnosis. However, the problem is often that people jump to the conclusion that it must be heatstroke, because it was a hot day.
In the coming days, as more news is made available about the race, we'll be sure to bring it to you. We have also attempted to make contact with doctors and researchers from the race to bring an inside line on what was happening around the medical tent, with the hope that we might be able to learn from Sunday's events for future races.
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