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Monday, October 08, 2007

Chicago Marathon death - autopsy result and further insights

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.


brad said...

Thanks for the educational and balanced posts. From the cnn.com headline this morning you were left assuming the heat caused the death if you were just casually browsing the news.

Ross Tucker and Jonathan Dugas said...

Hi Brad,

Thanks for visiting and for you interest in our work.

Our goal is to provide a balanced and scientific view of these kind of news items, and more importantly we want to give visitors something that they cannot get elsewhere in the mainstream media. So it sounds like mission accomplished, and thanks again for the comments.

Jonathan and Ross

heather said...

Hey guys
Thanks for all the great posts. We visit most days for some brilliant insights into the going-ons in the sporting world. Thanks for making it so reader friendly but super educational too!

Dr. John R. Brenner said...

Even if Mr. Schieber did not develop hyperthermia, heat and lack of sufficient hydration could well have contibuted to his death. He was doubtlessly sweating profusely while exerting himself on the hot day. This can result in intravascular hypovolemia (inadequate blood volume). In a person with a heart defect such as mitral valve prolapse, hypovolemia can more quickly lead to inadequate cardiac output, i.e. not enough blood getting to important organs, such as the heart and brain. When the heart does not get enough blood (myocardial ischemia), it is at much greater risk for an arrythmia as described above.

The body can compensate for the physical activity and high external temperatures by sweating, and thus maintain a normal temperature. However, the fluid lost in doing so can be deadly if not sufficiently replaced.

Ross Tucker and Jonathan Dugas said...

Hi John, and thanks for your interest in our blog and this post.

I hear you that hypovolemia can perhaps increase the chance of an arrythmia in an individual such as Chad Schieber. However, your statement that "the fluid lost in doing so [sweating] can be deadly if not sufficiently replaced" is unfounded and not supported by the scientific literature.

First, sweat rate is lower in individuals who are not acclimatized to the heat. A lack of acclimatization is in our opinion the main cause of collapse in most of the runners in the marathon (see our other posts for more in this topic). Therefore, if Chad Schieber was unacclimatized to the heat, which was unseasonable at this time of the year, then his sweat rate would be lower not higher.

Second, sweat rate is mostly a function of metabolic rate although it can be affected by the environmental conditions. According to the Chicago Marathon website, Mr. Schieber completed 30 km in 3:35:12. This is a pace of 11.5 minutes per mile and a five hour marathon. This represents a relatively low metabolic rate especially considering that Mr. Schieber was of normal weight.

Therefore as Exercise Physiologists we would not expect his sweat rate to be abnormally high, for example less than 1.2 L per hour. Even given this sweat rate and assuming he drank no fluid, after 3.5 h he would have lost approximately 5% of his body mass, which does not represent a health risk and is normal during endurance exercise.

In addition it is likely that he ingested some fluid during his run and therefore had most probably lost less than four Liters and therefore had lost less than 5% of his body mass.

Third, there is no published evidence that the environmental conditions such as those at the marathon elevate the risk of sudden death via a cardiac event during exercise.

Fourth, in endurance trained individuals such as Mr. Schieber the body adapts in such a manner that it is better able to maintain cardiac output during exercise, even in the heat, and this would suggest that he did not have a limiting cardiac output.

Fifth, reports from the race do not suggest that he complained of chest pains, which are normally the result of myocardial ischemia.

The incidence of sudden death in marathon runners is approximately 1:50,000, and it is most likely that Mr. Schieber falls into this unfortunately statistic as the evidence does not support any heat-related cause of death.

Thanks again for reading, and also for the comments. We hope the debate continues around this issue and the marathon.

Kind Regards,

John Brenner said...

I just now followed up on this post. I agree that it is presumptious to state that Mr. Schieber definitely was dehydrated or hypovolemic. However, as a long-distance runner and physician (resident anesthesiologist), I am hesitant to discount dehydration as a potential contributing factor in morbidity and mortality related to marathons.

As far as healthy people being able to maintain cardiac output in the face of modest dehydration, I certainly agree. Regarding literature, the studies I have read regarding exercise and hydration are done with relatively small numbers of young, healthy, athletic subjects. This is not very translatable to a large field of "all-comers," such as in the Chicago Marathon. Granted, there is some preselection in marathon entrants, but anyone could sign up for the Chicago Marathon regardless of their present shape. Out of 35,000 runners there will likely be some that will not tolerate even modest dehydration or hypovolemia especially well in the face of the other stressors present during a marathon.

Doug said...

He guys,
Great site and great information. I read the news yesterday about Ryan Shay. All these deaths and runners?
So my question? Should someone with MVP with regurgitation not race? Here's the reason. I was dx'ed with MVP with regurgitation about eight years ago (with an enlarged left ventricle like every other endurance athlete.)
Before diagnosed I played division I soccer in college and then turned to triathlons and running afterwards to fullfill my competitive juices. I am by no means elite, but I do have PR's of sub 35 10K, sub 2:50 marathon and have completed three Ironman Triathlons including qualifying for the Hawaii Ironman.
I love to compete, but I also have a wonderfull wife and three beautiful children.
I've had to echo's done and my cardiologist encourages me to continue exercising. My concerns are that the chicago marathoner was cleared to run as well as Shay. I know your not my doctor, but any news, research or data you can enlighten me with to either convince me to stop or encourage me to continue.
Thanks for your awesome site.

Ross Tucker and Jonathan Dugas said...

Hi Doug

Excellent question. And thanks, by the way, for the kind words.

To answer your question, it's a really tricky one. But it's so relevant, I'm actually going to try to do a post on that very issue this evening, and put out there some of the facts around sudden death. To give you the basic summary, there is a risk of sudden death, no one is immune, but some are more at risk than others. But provided everyone pay close attention to symptoms, have themselves checked out, the chances are so small that you would be over cautious not to exercise. For example, 2% of people have the condition you have - that means, in the Chicago Marathon, you can assume that about 700 people were running. Another 800 run in New York. And out of those 1500 (and probably 100000 elsewhere on the weekend who ran somewhere), only 1 person died.

now those are pretty small chances, so to me, having had yourself checked out, knowing the symptoms, and taking care, you should run.

of course, that's not a guarantee or a given, and I think you know that. There is risk, but ultimately, stopping what you love because of that risk is a decision you make, and I know what I would do.

But check out our latest post - it will be up in a couple of hours, at most.

Thanks again! Keep visiting!

Kenneth said...

Who said anything about heatstroke. Many experts have testified that MVP would not alone kill a marathoner. Could dehydration bring on the Arrythmia answer yes. To say the marathon had no impact on this man is a false statement. The result is inconclusive in my opinion.

Ross Tucker and Jonathan Dugas said...

Thanks for the comments on this post, Peet!

I can recall when Romanav came to Cape Town and showed us all the premise for the Pose technique.

Initially I was skeptical. However I picked up a soleus injury that would not get better, and I was in the middle of some hectic training for a marathon. Out of desperation learned the Pose techinque so I could keep training.

The first important point is that it allowed me to continue running and training hard because it reduced the impact forces on my lower legs. I ran a five km time trial one month before the marathon and decided I was not running any slower than pre-Pose.

The second point is that I ran close to a best time with Pose. I was aiming for a 2:35 marathon. With the injury in August, I lost some training during a critical time point, and figured that my final time of 2:52 was probably close to my "actual" potential at that point in time, regardless of running technique.

To refer now to Peet's comment, most motor skills we perform as humans are called "phylogenetic skills" and include locomotion such as crawling, walking, and running. Also included are throwing and swinging a bat or implement. Other skills such as a tennis swing or golf swing are called "ontogenetic" and most certainly, as Ross mentioned, require coaching to learn due to their technical nature.

The take home message about phylogenetic skills is that they do not require any coaching to learn, and as long as someone does it, they learn them, and the more they do that skill, the better they get.

So for example we do not need to be taught how to walk. We do it on our own when we are ready for it, and once we start we keep on doing it and get better and better without any coaching by our parents.

The same goes for throwing and swinging, although if you watch any little league baseball here in America you will see kids being over-coached when all they need to do is just practice and actually do the activity and they will improve.

Again, throwing a ball is the same type of skill, and motor development scientists actually assign different levels (1-4) of each skill, and have described how kids are Level 1 throwers from ages "x" to "y," and Level 2 normally from age "x" to "y," and so on.

Often one does not spend sufficient time in an activity to reach Level 4, for example Peet has labeled himself an "inefficient" thrower. Given you age, Peet, you may or may not be able to reach a higher level of throwing. I am uncertain as I am not entirely dialed in to the finer aspects of Motor Learning and if phylogenetic skills can be improved once one has reached adulthood.

Having said all of that, at a higher level of running, I agree with Ross that working with an athlete on small aspects of his/her running can certainly result in improvements in performance. It does not matter if the change results in a physiological change in efficiency, because at the end of the day the person is still running faster!


Anonymous said...

Because mitral valve prolapse is relatively common, do you think it would make sense for high school cross country athletes to be screened -- and, if they have MVP, the extent of their regurgitation assessed -- before participating in everyday runs and competing in
5-K races? What about a HS cross country runner whose mother and both maternal grandparents have MVP with some regurgitation?

Ross Tucker and Jonathan Dugas said...

Hi Karen

Thanks for the question, which is certainly relevant and topical.

My personal opinion is that screening is only part of the answer. Because MVP is so common, you create an ethical dilemma when you screen and find that out of 1000 people, 20 have the condition. What do you do then? Because out of say 1000 people who have the condition, only maybe 1 is potentially at risk - the vast majority of people who have MVP never experience any effects, let alone sudden death

So not only do we have a major economic impact of screening all young athletes (a view that may seem callous - assigning monetary value to health, but valid nevertheless), but you also have a situation where even with a positive diagnosis, you still can't make any decision that is guaranteed to be correct - do we ban those with MVP from exercise, given the low risk? We might then also ban people from driving cars, because the risk of death is about 1% there too, perhaps! That's a bit tongue in cheek, but illustrates the point.

Still, an interesting debate, one I'm sure could go on a long time. We tried to cover it in a bit more detail in a subsequent post called "Sudden Death during exercise - What does it mean for YOU?". IN this post, we tried to look at the symptoms, which are more important in the diagnosis and prevention of such sad events. To sum up, my angle would be to focus on education, rather than mass screening.

Thanks for the question, and join us again!


Ross Tucker and Jonathan Dugas said...

Hi Karen, and thank for commenting on our work here at the Science of Sport.

As a scientist, I agree with Ross. We have to look at the available evidence, and that suggests that the risk is sufficiently low not to screen all kids participating in sports. The risk is just too low for this kind of approach to make sense.

Education is certainly the key, and one must be cognizant of family history. Given the fact that a child's grandparents and mother have MVP, screening to identify that condition certainly seems appropriate.

But then I would stress that just being identified as having MVP should not preclude a teen from running (or participating in any sport), because again, the benefits of regular exercise far outweigh the risks of sudden death, even in someone who has MVP.

Finally, in the end it is up to the individual and his/her family to 1) seek info (i.e., get screened), 2) garner a second or even third opinion, and 3) actually decide what is prudent for them. Medicine and science can only get us so far, and ultimately we have to make the final call.

Thanks again for posting!

Kind Regards,

Real Pinko said...

I think you are one of Pinkowskis paid goons to lie about this death. It is correct the autopsy showed MVP but it is not in any way correct it showed he died of MVP. I have talked to 5 cardiologists and NOT ONE CARDIOLOGIST believes MVP did this. He maybe shouldn't have been running in the heat, but don't blame something falsely. Especially when Pinko stiffed so many people of basic requirements of the race like water. I hope you can sleep at night, patsy.

Ross Tucker and Jonathan Dugas said...

Dear Real Pinko

We've had a few pretty mindless comments on this site in the last 18 months. Yours had the potential to contribute very nicely to the debate, but it degenerated into what must be the stupidest one we’ve had. You take what might have been a very valid question regarding the apparent opinion of your cardiologist friends, and you tarnish it by launching a baseless, idiotic personal attack that culminates in an accusation of “patsy”, when you yourself have no basis to argue from, no point of view other than that given to you by friends who may as well be imaginary. How about you come back another time with any shred of proof that the lack of water was in any way responsible for the death of Schieber, and then we can discuss the issue further?

You end off by adding your voice to the hundreds of others who have been told of the dangers of under-drinking. Did it occur to you that the death of Chad Schieber occurred despite the fact that he had access to the water? He was one of the top 20% of runners. There is actually a photograph of him, taken during the race, drinking at a water table, with plenty available. The shortage of water came later, after runners of his ability had long passed through the stations.

If (and this is a big if) the death happened later, to one of the runners who actually was caught out with no water, then I might give your question 10 seconds worth of consideration. As it is, it’s offensive and idiotic.