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Dr Larry Creswell

Dr. Larry Creswell on athletes and heart health.
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More on Triathlon Fatalities–A Scientific Report

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Readers here at the blog will know that I’ve had a long-standing interest in triathlon fatalities. My interest was originally sparked by media reports and the paradox that seemingly healthy and fit triathletes might die on race day.

I was involved with an internal review of this problem at USA Triathlon (USAT), the governing body for the sport of triathlon in the United States. In 2011, that task force issued a formal report and set of recommendations for athletes, event organizers, and USAT itself.  Those written recommendations are still valuable today as we work to reduce the number of triathlon race-related fatalities.

In this week’s edition of Annals of Internal Medicine, I joined with Drs. Kevin Harris and Barry Maron from the Minneapolis Heart Institute in reporting on “Death and Cardiac Arrest in U.S. Triathlon Participants, 1985-2016:  A Case Series.”  In this scientific report, we’ve gathered information about 122 athletes who died and another 13 athletes who suffered cardiac arrest but survived during triathlon races in the United States over the past 3 decades.  This is, by far, the most comprehensive scientific report on this subject.

Special thanks go to the leadership at USAT which recognized the importance of this issue, has been proactive in working to reduce the number of race-related fatalities, and was extraordinarily helpful to our investigative team as we assembled the information for our new report.

 

The Important Observations

  • Victims were 47 +/- 12 years old
  • 85% were men
  • Almost 40% were first-time triathlon participants
  • There were no elite or professional athletes among the victims
  • The overall rate for fatalities or cardiac arrest was 1.74 per 100,000 participants (2.40 for men, 0.79 for women). For comparison, the rates of cardiac arrest (including fatalities) are approximately 1.0 per 100,000 participants in marathons and 0.3 per 100,000 participants in half marathons.
  • The fatality risk in triathlon increases exponentially with age; the fatality rate was 18.6 per 100,000 participants among men 60+ years old
  • Fatality rates were similar for short, intermediate, and long-distance races
  • The majority of deaths (74%) occurred during the swim segment; smaller numbers of deaths occurred during the bike or run segments or after finishing the race
  • Among 22 fatalities occurring during the bike segment, 15 were due to traumatic injuries
  • At autopsy, clinically relevant (but presumably previously unrecognized) heart/vascular disease was found in many victims

 

A Recipe for Doing Better

We should focus on two strategies for reducing the number of fatalities:  1) we should work to prevent incidents of race-related cardiac arrest and 2) we should work to improve the survival rate for any such victims of cardiac arrest.  Athletes, physicians, event organizers, safety personnel, and sport governing bodies can all play an important role.

Athletes should:

  • Make certain that their participation in a particular race is in keeping with their health, both chronic and acute, as well as their ability and preparation.
  • Consider their heart health before participating. This may be particularly true for first-time participants and for men who have reached middle age. For older men, testing for “hidden” coronary artery disease (CAD) or other forms of cardiovascular disease may be appropriate.
  • Assess their health on race day and consider not racing if they are “sick.” Symptoms, particularly systemic symptoms like fever, are related to DNF rates in other sports settings.
  • Be prepared for the rigors of a triathlon swim. It is important to be a capable swimmer and to have practiced open water swimming in advance of the race.
  • Think to STOP at the first sign of medical troubles (unexplained shortness of breath, chest pain/discomfort, or light-headedness), particularly during the swim segment.

Physicians should:

  • Be aware of the risks of participating in triathlon and be in a position to counsel their athlete patients about those risks in the context of the patient’s specific health situation.
  • Consider the potential value of cardiac screening, particularly for occult CAD in men who have reached middle age. Evidence-based screening protocols are not yet available, so an approach will need to be individualized. In most cases, an evaluation of the traditional risk factors for CAD would be appropriate and in some cases, additional testing such as calcium-scoring cardiac CT or stress testing may be appropriate. Athletes who are just beginning an exercise program should receive special attention in this regard.

Event organizers should:

  • Develop a robust safety plan, particularly for the swim segment, that enables prompt (near instantaneous) identification of a lifeless victim, and then rescue of that individual to a location where CPR, defibrillation, and advanced life support can be provided.
  • Have a communication system for all individuals involved in race-day safety.
  • Rehearse the safety response to a lifeless victim, especially for the swim segment.

Race-day safety officials should:

  • Be trained in CPR and use of the AED.
  • Be familiar, through rehearsal, with the communication and safety plans.

Sports governing bodies should:

  • Provide education for athletes, event organizers, medical directors, and volunteer safety officials about life-threatening race-day emergencies.
  • Develop rules and sanctioning requirements that promote athlete safety.

 

Reference:

  1. Harris KM, Creswell LL, Haas TS, Thomas T, Tung M, Isaacson E, Garberich RF, Maron BJ. Death and cardiac arrest in U.S. triathlon participants. Annals of Internal Medicine 2017 (in press).

 

Related Posts:

  1. Should You Race When You’re Sick?
  2. Triathlon Fatalities: 2013 in Review
  3. New USA Triathlon Water Temperature Safety Recommendations
  4. Fatal Arrhythmias in Open Water Swimming: What’s the Mechanism?

In the Medical News: Does Heart Function Suffer in Long-term Endurance Athletes?

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Gym

Background

Moderate amounts of exercise produce a multitude of health benefits.  Both the American Heart Association (AHA) and World Health Association (WHO) now recommend 150 min per week of moderate intensity exercise for adults.

Some recent observations, though, have raised the question:  when it comes to exercise, can there be too much of a good thing?  And, more specifically, can too much exercise somehow be harmful to the heart.  With the increased popularity of adult recreational and competitive sports–particularly in cycling, running, and triathlon–there is a growing number of adults who are pursuing exercise far in excess of the AHA and WHO recommendations.  The questions surrounding the issue of “too much exercise” are very pertinent.

A few recent articles in the popular press summarize some of the findings and frame the debate:

The worrisome observations have generally been made in small numbers of symptomatic athletes, in groups of athletes whose athletic history–or “dose” of exercise is poorly characterized, or in studies that were designed for some purpose other than determining the effects of “too much exercise” on the heart.

I’ve said previously that these observations deserve our attention, but that we really need more targeted investigation into this issue.  In a study just released online (ahead of print) in the medical journal, Circulation, Philipp Bohm and colleagues from the Institute of Sports and Preventive Medicine at Saarland University in Germany bring us an important new look at “extreme” exercisers.

 

The Study

This new study focuses on a group of 33 healthy, male, Caucasian competitive elite master endurance athletes.  This group of athletes was selected so that it included only athletes with a 10+ year continuous training history of 10+ hours per week; the average training was 16.7 hours per week and the average training history was 29 +/- 8 years.  These athletes had an average age of 47 years (range, 30-60 years).  This group of athletes included:

  • Sixteen were former elite professional athletes
  • One Ironman world champion and several 2nd and 3rd place finishers
  • The world record holder at the long distance triathlon
  • A 2nd ranked cyclist of the Vuelta a Espana (Tour of Spain)
  • Six Olympic athletes in the sports of triathlon and rowing
  • A former winner of the Munich Marathon.

A control group consisted of 33 healthy Caucasian men who were pair-matched for age, height, and weight.  This control group was selected to include only individuals who exercised <3 hours per week.

All of the subjects underwent a comprehensive evaluation that included:

  • History and physical examination (to exclude any athlete with a history of overt heart disease, high blood pressure, smoking history, or other risk factor for heart disease)
  • Resting EKG
  • Cardiopulmonary exercise testing
  • Echocardiography, including tissue-Doppler imaging and speckle tracking
  • Contrast-enhanced cardiovascular magnetic resonance imaging (CMR).

Interestingly, none of the athletes presented with, or reported a history of, atrial fibrillation.

There were several unsurprising, and expected differences between the athletes and the controls.  First, the resting heart rate (HR) for the athletes (48 +/- 7 beats per minute) was slower than for the controls (65 +/- 11 beats per minute).  Second, the size of the athletes’ hearts was significantly greater.  The left ventricular (LV) mass for the athletes’ hearts (188 +/- 26 g) was significantly greater than the controls (124 +/- 23 g).  Similarly, the right ventricular (RV) mass for the athletes’ hearts (70 +/- 13 g) was significantly greater than the controls (49 +/- 11 g).  Among the 33 athletes, 22 met a traditional definition of “athlete’s heart,” with a heart volume of 13+ mL/kg of body weight.  As expected, the VO2 max of the athletes (60 +/-5 ml/kg/min) was significantly greater than controls (37 +/- 6 ml/kg/min).

The important results of the study were those that showed no difference between the athletes and the controls.  With echocardiography, there was no difference between athletes and controls in LV longitudinal strain or RV longitudinal strain–measures of the strength of contraction.  Using CMR, there was no difference between athletes and controls in LV ejection fraction (EF) or RV EF–again, measures of the strength of contraction.  One athlete (3%) had a LV EF slightly less than normal, at 45%.  No athletes or control subjects had abnormalities of the RV that could be suggestive of the potentially life-threatening problem of arrhythmogenic right ventricular cardiomyopathy (ARVC).  One athlete (3%) had late gadolinium enhancement (LGE) on CMR that suggested previous, asymptomatic inflammation of the pericardium, the sac in which the heart sits.  LGE analysis showed no evidence of unusual fibrosis or scarring in either athletes or controls.

 

My Thoughts

Kudos to the investigators here.  The study is apparently self-funded.  It’s expensive to perform this kind of testing; in the United States, the costs of this study would easily run into the many hundreds of thousands of dollars.  Kudos, too, to the editors at Circulation.  There is a tremendous bias against publishing so-called “negative” studies, where no important differences are found between study and control groups.  Many “negative” studies are left on the editing room floor–and we never hear about them.

This is an important study because it is the first to gather and study a group of long-term endurance athletes with a substantial, and defined, training load over an extended period of time.  The results deserve our attention.  At nearly 17 hours per week of exercise or training, these athletes obviously far exceeded the contemporary recommendations for 150 minutes of moderate exercise per week.  Just doing some quick math, the average cumulative exercise “dose” is more than 25,000 hours.  As I’ve said many times before, it’s worth asking the question if such an exercise pattern can be harmful to the heart over the long term.  This is a terrific group of athletes to study in order to help answer that question.

We must keep in mind that, with just 33 athletes, this is a small study.  With only 33 athletes, it’s obviously possible to miss something that would be found in the 34th athlete.  We must also keep in mind that the study only involves male athletes.  Female athletes are not immune from heart problems and deserve study, too.

It is a striking finding that no athlete was found to have atrial fibrillation–either now, or in the past.  Moreover, no athletes experienced arrhythmias during the cardiopulmonary exercise test.  A number of previous studies have reported a 2- to 5-fold increase in atrial arrhythmias among long-term endurance athletes.  Like the current study, all of those previous studies have involved small number of athletes.  None, though, have focused on athletes like these, with such extensive exercise and training histories.  In my opinion, endurance athletes broadly can take some comfort from the findings of this new study with regard to the potential risk of atrial arrhythmias.

It’s noteworthy that the LV and RV function of the athletes was no different than the controls.  One athlete had mildly depressed LV function, for reasons that are not clear.  In short, though, the study found no evidence of cardiac damage–at least, in terms of the pumping function–that accrued over the long term.  We know that there is some depression of LV and RV function immediately after an intense bout of exercise (eg, marathon, long-distance triathlon, long-distance cycling event), but we also know that these changes resolve within days to weeks afterward.  The current study argues against the hypothesis that repeated episodes of intense exercise (ie, many marathons or triathlons over a lifetime) might result in a decrease in LV or RV function.  Again, this is encouraging news for endurance athletes.

Finally, the CMR and LGE results are important.  Aside from the 1 athlete with possible previous pericarditis, there were no worrisome findings of fibrosis or scarring that might be attributable to injury from repeated episodes of intense, strenuous exercise.  These LGE findings are at odds with some observations of unexplained fibrosis in other cohorts of long-time runners, even if the consequences of such findings remain uncertain.  This area of investigation deserves further attention.  For now, I’d say that long-time participation in endurance sports does not necessarily result in unexplained fibrosis in the heart.

 

Related Posts:

  1. Thoughts on the recent VeloNews article
  2. PRO/CON:  Prolonged intense exercise leads to heart damage
  3. Do elite athletes live longer?