Update on Swimming Induced Pulmonary Edema (SIPE)

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I saw this week that there was an important new paper on swimming induced pulmonary edema (SIPE).  Richard Moon, MD, and his colleagues at Duke University published a report entitled, “Immersion Pulmonary Edema and Comorbidities:  Case Series and Updated Review” in a recent edition of the sports medicine journal, Medicine & Science in Sports & Exercise (1).

SIPE is known to occur not only in recreational or competitive swimmers, but also in divers.  In fact, the condition was first recognized because of breathing difficulties encountered by military divers.  As triathlete and swimmer readers here will know, there are many reasons why an athlete might develop shortness of breath during an open water swim.  Water conditions, water and air temperature, exertion, and anxiety all play a role.  SIPE is something different, altogether, though.  This is a condition that develops because of immersion in the water, in which fluid builds up in the lungs and makes breathing difficult.  The condition is believed to be self-limiting; if a swimmer gets out of the water, the condition will resolve.  The underlying mechanisms and risk factors are not completely understood.

I’ve written about this condition in 2 previous blog posts….SIPE and More on SIPE.  These posts might be a good starting point.

The newly published report is important because it reviews the medical literature and gathers all of the pertinent information about pre-existing medical conditions, or so-called comorbidities, in victims of SIPE.  Dr. Moon is probably the world’s foremost authority on the topic of SIPE, so this new report deserves our attention.

 

The Study

There are 2 parts to the study:  1) a look at the Duke University experience with recreational swimmers who’ve had a SIPE episode and 2) a review of the medical literature on SIPE cases, both in military and recreational divers and swimmers.

In the first part, the investigators collated information on 41 swimmers who, over the past several years, had been studied at Duke University after reporting a SIPE episode.  The mean age was 50.1 +/- 10.8 years (range, 25-71 years).  Complete medical history data was available for 36 of the 41 swimmers.

In the second part, the investigators collected 45 previously published articles in the medical literature that reported on 292 cases of SIPE.  There were 156 recreational swimmers or divers (89 men and 67 women), with a mean age of approximately 47.8 +/- 11.3 years.  There were also 136 military swimmers or divers (135 men and 1 woman), with a mean age of approximately 23.3 years (range, 18-47 years).

For each of these groups, the investigators gathered information about pre-existing medical conditions in order to determine potential risk factors for the development of SIPE, focusing on:  hypertension (high blood pressure), lung disease, overweight/obesity, sleep apnea, hypothyroidism, and cardiac abnormalities).

 

The Results

Among the Duke University group, 9 (25%) of the 36 swimmers with available health history were completely healthy.  The remaining 27 (75%) had 1 or more medical/health conditions, including:

  • overweight/obesity in 12
  • hypertension in 7
  • cardiac arrhythmias in 4
  • heart valve problem (mitral valve prolapse) in 1
  • reduced heart function in 2
  • repaired congenital heart conditions in 2
  • asthma in 3
  • COPD in 1
  • reactive airways disease in 1
  • hypothyroidism in 3
  • diabetes in 2
  • polycystic ovary syndrome in 1
  • obstructive sleep apnea in 2

Twelve subjects had more than one of these conditions.

In the literature review, all of the 136 military swimmers and divers were healthy; they had none of the pre-existing medical/health conditions that were surveyed.  In contrast, 70 (45%) of the 156 recreational swimmers or divers had one or more significant pre-existing risk factors:

  • asthma in 4
  • enlarged heart in 2
  • arrhythmias in 2
  • coronary artery disease in 3
  • diabetes in 4
  • exercise-induced cough in 1
  • Elevated serum lipids in 22
  • hypertension (high blood pressure) in 25
  • thickening of the left ventricle in 9
  • peripheral vascular disease in 1
  • sleep apnea in 6

As a side note, approximately 17% of cases in the literature review reported similar previous episodes or follow-up episodes that were suggestive of SIPE, giving an important look at the potential recurrence rate.  And in total, 6 fatal cases of SIPE were identified in the literature review.

 

My Thoughts

How can all of this collated information be useful to us?

First, it’s important to note that all of the military swimmers and divers included in the literature review were healthy.  We shouldn’t overlook the possibility that even completely healthy swimmers may experience SIPE.

Second, the recurrence rate of ~17% in the literature review is probably an underestimate.  No doubt, some swimmers who experienced a worrisome episode of SIPE might avoid future swimming altogether.  It’s very important to remember that this condition may recur.

Third, it’s very apparent that, among recreational swimmers who experience SIPE, the prevalence of important pre-existing medical conditions is rather high, at 75% in the Duke group and 45% in the recreational swimmers in the literature review.  I suspect that the Duke investigators were more thorough in their history-taking and the 75% is probably more reflective of the reality.

The investigators’ aim was to identify risk factors for SIPE.  Sadly, there’s obviously no single, unifying thread here.  Hypertension (high blood pressure) was the most commonly identified condition among the cases, but this accounted for only ~15% of the cases.  As I mentioned at the top, the physiologic underpinnings of SIPE are not completely understood and indeed there may be more than one responsible mechanism leading to some common final pathway by which fluid accumulates in the lungs.  All of the various cardiovascular abnormalities identified in the cases might conceivably play a role.  There’s more to learn.

It’s worth noting that the long list of medical conditions that were identified deserve careful medical attention before participating in recreational swimming events.

 

Advice

I’ll reprint here my best advice to athletes and event organizers regarding SIPE.  I originally included this in another blog post, but this is still my best advice!

  1. Triathletes and open water swimmers should be aware of SIPE and the possibility that this condition can be lethal.
  2. Symptoms of SIPE can manifest for the first time even in experienced swimmers.  Symptoms may develop rapidly, be unexpected, and confuse the athlete about the cause.
  3. The development of SIPE does not appear to be confined to cold water swims or only to victims who are wearing a wetsuit at the time.
  4. SIPE appears to be self-limiting–that is, the symptoms will subside if the victim stops exercising and gets out of the water.
  5. Because of #2, #3, and #4, athletes who experience breathing difficulties in the open water should treat the problem like a medical emergency and STOP swimming and SEEK immediate assistance.  Because of the challenges of rescue in the open water, your life could depend on recognizing a problem early and getting out of the water.  I would encourage affected athletes to get complete medical evaluation as soon as possible after an episode.
  6. There appear to be no effects on lung function after an episode of SIPE, but repeat episodes of SIPE may occur.
  7. Affected athletes have described a variety of strategies for preventing repeat episodes of SIPE.  From athlete accounts, no single strategy appears to be universally successful.
  8. Affected athletes should use EXTREME CAUTION in subsequent open water training and races, being hypervigilant for warning signs.
  9. Event organizers and on-water rescue personnel should be familiar with SIPE.  The safety plan should allow for athletes with breathing difficulties to be removed from the water as quickly as possible.

 

Reference

1.  Peacher DF, Martina S, Otteni C, et al.  Immersion pulmonary edema and comorbidities:  Case series and updated review.  Med Sci Sports Exerc 2015;47(6):1128-1134.

 

Related Posts:

1.  Swimming Induced Pulmonary Edema (SIPE)

2.  More on Swimming Induced Pulmonary Edema (SIPE)

USAT Medical Multisport Conference

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I had the chance to be a speaker at the November, 2014 USA Triathlon (USAT) Medical Multisport Conference that was held at the Olympic Training Center in Colorado Springs.  The weekend brought 2 days of talks that focused on aspects of sports medicine that were particularly relevant to triathlon and multisport.

Travis Tygart, CEO of the United States Anti-Doping Agency (USADA) was the keynote speaker.  We heard about event and safety planning from a very experienced group of USAT-affiliated physicians, including W. Douglas Hiller, MD, Andrew Hunt, MD, and John M. Martinez, MD.  I gave talks on some of my favorite topics:  “Triathlon Fatalities,” “Endurance Sport:  Is it Heart Healthy?,” and “Cardiovascular Considerations in the Aging Athlete.”  We had lunch with Kathy Matejka, the USAT Event Services Director and dinner with Rob Urbach, CEO of USAT.

I met some terrific folks and I learned a lot.

It was great to visit the Olympic Training Center.  I particularly enjoyed the museum area and a workout at the pool.  The snow and cold weather got the best of a planned group run, though.

This year’s Conference is planned for November 5-7, 2015, again at the Olympic Training Center in Colorado Springs.  This year’s keynote speaker will be Robert Laird, MD, the original and long-time medical director for the Ironman World Championship race in Kona, Hawaii.  This would be a worthwhile meeting for anybody who’s involved with medical care of multisport athletes, including nurses, physicians, and allied health professionals.  Information about the meeting schedule, speakers, and registration can be found at the USAT website.

I hope that you’re able to join us in November!

Triathlon, Open Water Swimming, and the Heart: What Can We Learn From Dolphins and Seals?

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A recent study about marine mammals caught my eye.  I don’t know much about non-human biology and physiology, but this study on dolphins and seals may shed some light on the problem of fatalities during open water swimming or triathlon events.

The Study

A group of investigators headed by Terrie Williams from the University of California at Santa Cruz shared their report, “Exercise at depth alters bradycardia and incidence of cardiac anomalies in deep-diving marine mammals” in the January 16th edition of Nature Communications (1).

This group of investigators has been interested in the physiology of the so-called “dive response” in marine mammals.  This is a response that is governed by the involuntary, or autonomic, nervous system, which has two antagonistic components:  the parasympathetic nervous system and the sympathetic nervous system.  As a group, the marine mammals depend on feeding by chasing pray to depths that can range up to 3,000 m.  Even at lesser depths, these mammals must maintain a breath-hold under large hydrostatic pressures while they undergo extreme exertion to catch their pray.  During a dive, breath-holding stimulates the parasympathetic nervous system to slow the heart rate (producing bradycardia).  At the same time, the exertion required to chase pray stimulates the sympathetic nervous system, producing an increase in the heart rate.  The current study offers the first detailed study of the interplay between the components of the autonomic nervous system during routine diving and feeding activity in these animals.

The investigators created an electrocardiograph-accelerometer depth monitor that was deployed on 10 Atlantic bottle-nosed dolphins and 3 Weddell seals.  This device allowed high-fidelity recording of the heart rate, ECG, water depth, and swimming stroke frequency (a measure of exertion) during dives.  For the dolphins, measurements were made for 74 dives to depths of up to 210 m.  For the seals, measurements were made for 91 dives to depths of up to 390 m.

The Results

As expected, there was a strong relationship between diving depth and heart rate for both species, with heart rates falling during descent and reaching a minimum at the lowest depth of the dive.  Superimposed on this effect was an additional effect of exertion.  For the dolphins, the maximum heart rate was 1.7 to 3.7 times greater during periods of extreme exercise compared to gliding alone.  For the seals, the maximum heart rate was 1.5 to 1.8 times greater during periods of extreme exercise compared to gliding alone.

The surprising finding was that cardiac arrhythmias occurred in more than 73% of the dives.  The investigators defined arrhythmias to include ectopic beats or significantly increased variability in the interbeat interval (IBI).  There were apparently no sustained or fatal arrhythmias., but there were discrete examples of “wandering pacemaker” and ventricular premature beats.  In the Weddell seals, there were often patterns of alternating periods of tachycardia (fast heart rate) and bradycardia (low heart rate) during periods of constant, intense exertion.

The presence of cardiac arrhythmias was strongly correlated with increased depth of dive (parasympathetic activation) and increased exertion (sympathetic activation).  As an example, cardiac arrhythmias occurred in 81% of the dolphin dives to >210 m but in only 26% of dives to <100 m.

The authors concluded that our previous understanding of the dive reflex in marine mammals was not totally correct.  Given that these animals depend on diving for their food sources, the development of cardiac arrhythmias during feeding appears to be mal-adaptive.  In fact, feeding might actually be dangerous.

My Thoughts

At first glance, the physiology of the diving response of dolphins and seals during feeding seems far afield from open water swimming and triathlon.  And moreover, we already know about the development of cardiac arrhythmias during submersion in breath-holding humans as well as other marine species.  The important observation here, though, is what I might call “irritability” or “instability” in the heart rhythm during periods of intense parasympathetic and intense sympathetic activation….and that’s the possible link to human fatalities during open water swimming or triathlon.

We know from autopsy reports of triathletes who’ve died during the swim portion of an event that there are sometimes only subtle abnormalities of the heart, and often nothing that seems explanatory.  That leaves us in a difficult position to explain such deaths.  In a previous blog post, I wrote about one very plausible hypothesis. Two UK physiologist,s X and X, proposed the concept of “autonomic conflict,” where a surge in both the parasympathetic and sympathetic stimulation of the heart might lead to a fatal arrhythmia.  I’ve been intrigued with this hypothesis because it seems to fit many of the observations made about the swim victims.  It is easy to see where exertion, cold water, anxiety, etc. might lead to strong sympathetic activation.  And it’s equally easy to see where facial wetting, water entering the mouth/hypopharynx/nasopharynx, and breath-holding, even without diving, might lead to strong parasympathetic activation.  In that instant, in an athlete with some sort of susceptible heart, a fatal arrhythmia might occur.

The new observations about the dolphins and seals seem to play into this hypothesis.

 

Related Posts:

1. Fatalities in Open Water Swimming:  What’s the Mechanism?

2. Triathlon Fatalities:  2013 in Review

 

Reference:

1.  Williams TM, Fuirman LA, Kendall T, et al.  Exercise at depth alters bradycardia and incidence of cardiac anomalies in deep-diving marine mammals.  Nature Communications 2015;6:6055.

 

 

 

Book Review: Heart to Start

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Check out the newly published “Heart to Start:  The Eight Week Exercise Prescription to Live Longer, Beat Heart Disease, and Run Your Best Race,” by cardiologist, James Beckerman, M.D.  The book is available at Amazon and other outlets.

This is a terrific book!

First, let me share a little bit about the author.  Dr. Beckerman is the Medical Director of the Center for Prevention and Wellness at the Providence Heart and Vascular Institute in Portland, Oregon.  He is also the team cardiologist for the Portland Timbers Major League Soccer team and the founder and medical director for Portland’s Play Smart Youth Heart Screenings.  He is passionate about wellness, exercise, and preventive cardiology.  Follow him on Twitter at @jamesbeckerman.

Perhaps you’ve had a heart attack and your doctor has recommended exercise.

Perhaps you’ve discovered that your blood pressure or cholesterol is elevated and your doctor has suggested exercise as a treatment.

Perhaps you’ve just decided to get up off the couch and be more active.

The inevitable question is, “How do I get started?”  This book is for you!  In Dr. Beckerman’s words, “This is a book about exercise and I guarantee that it will move you….”.  More coach than doctor, he will guide you every step of the way as you get going.  Take him up on the offer.

This book starts with a very personal and riveting Foreword by Dave Watkins.  He asks, “What is your legacy?”  He shares his near-death experience with urgent heart surgery for a diseased heart valve and aortic aneurysm on the verge of rupture.  There were certainly ups and downs during Dave’s recovery, but he survived and then some!  Read about Dave’s return to exercise, his successes in triathlon, and the founding of his Ironheart Foundation.  Dave’s story will provide ample motivation.

The book is divided into 3 sections….

Warm Up.  In the first section, Dr. Beckerman helps you to take stock of your health in general and your heart in particular.  He introduces the concept of preventive cardiology and illustrates this with real-world examples where “an ounce of prevention is worth a pound of cure.”  Dr. Beckerman shows you how to use the Sit Rise Test and the 6-minute walk test to size up your fitness level.  This section concludes with a discussion of how traditional cardiac rehab and structured exercise can be so valuable.

Workout.  In the second section, Dr. Beckerman lays out what he calls your “Heart to Start Exercise Prescription.”  You’ll start with an assessment of your VO2max, an index of your aerobic capacity or fitness, and then embark on an 8-week exercise program that is tailored to your fitness level.  There are both HEART (aerobic exercise) and START (strength exercise) components.  The program is structured but simple.

Cool Down.  In the final section, Dr. Beckerman sums things up.  He recognizes that there are always choices and asks you to remember to consider, “What would a healthy person do?”  For those wishing to continue on, he leaves you with a 12-week exercise program that will get you to the start line of a 5K running race.  It’s a program that he uses in Portland with his popular Heart to Start group (see the photo).  You can be sure that the program works.

H2S

 

 

 

 

 

This book is for….

If you’re ready to get going, take a copy of “Heart to Start” to your next doctor’s visit and talk about getting started.  Team up with your doctor to put Dr. Beckerman’s exercise prescription to work for you.

For many readers here at the blog, exercise may already be an important part of your routine.  But I bet you know others, perhaps in your own family, who haven’t yet embraced exercise.  Get them a copy of the book and help them get started.

Perhaps you’re in a position to organize a group exercise program like Dr. Beckerman’s Heart to Start program.  I bet he’d be happy to hear from you and help you get things organized.

 

Related Posts (Other Book Reviews):

1. Cardiac Athletes, by Lars Andrews

2.  The Exercise Cure, by Jordan Metzl, MD

 

In the News: Cardiac Screening for Adult Recreational Athletes

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An important new study caught my eye.  In last week’s British Journal of Sports Medicine, Andrea Menafoglio and her colleagues from Bellinzona, Switzerland published (epublished ahead of print) a report entitled, “Cardiovascular evaluation of middle-aged individuals engaged in high-intensity sport activities:  implications for workload, yield and economic costs.”(1)

The study is important because it addresses the issue of cardiovascular screening in adult, recreational athletes, an area that’s received very little attention.

By comparison, the issue of cardiac screening for young, competitive athletes has received a great deal of attention over the past 25 years.  Many prominent medical scientific organizations have issued recommendations for pre-participation screening in young athletes, including the American Heart Association (1), American College of Cardiology (ACC), American Academy of Family Practice (AAFP), American Academy of Pediatrics (AAP), American College of Sports Medicine (ACSM), American Medical Society for Sports Medicine (AMSSM), just to name some of the American organizations.

These recommendations form the basis for the widespread use of mandatory pre-participation screening in secondary schools and colleges. The goal of such screening programs is to reduce the number of fatalities from sudden cardiac problems that arise during sporting activities.   The successes and pitfalls of such screening programs have been reported and the findings have engendered lively debate about what elements to include in screening programs, their effectiveness, and justification of their cost.

In this new study, the investigators report on a “real world” glimpse into cardiovascular screening in adult, recreational athletes.  Their aims were to evaluate the practicality of such a screening program, to measure the prevalence of previously unrecognized cardiovascular conditions in this group, and to determine the costs associated with initial screening and follow-up evaluation of athletes with an abnormal initial evaluation.

 

The Study

The investigators enrolled 785 athletes, aged 35-65 years (mean, 46.8 years), who engaged in “high-intensity sports” for at least 2 hours per week.  The athletes’ sports included running (in 33%) and cycling (in 24%), among others.  The majority of subjects (73%) were male.  The athletes were primarily “amateur” (69.7), but the group included some who competed in regional (23.7%), national (4.6%), or international competition (2.0%).

Athletes with a known history of cardiovascular disease, except for treated high blood pressure, as well as athletes who had previously undergone cardiac screening within the previous year were excluded.

Each athlete underwent a cardiac screening evaluation according to the current guidelines established by the European Association of Cardiovascular Prevention and Rehabilitation (EACPR).  The evaluation was free to each athlete and included:

  • Thorough personal and family medical history
  • Physical examination
  • ECG
  • Estimation of the individual’s cardiovascular risk using the Systemic Coronary Risk Evaluation (SCORE) chart for Switzerland
  • Blood testing for total cholesterol and serum glucose.

The SCORE chart was used to estimate the athlete’s 10-year risk of death due to atherosclerotic heart disease based on gender, age, total cholesterol level, systolic blood pressure, and smoking status.  Athletes were deemed at “high risk” if their predicted risk was >5% or if any single risk factor (eg, total cholesterol, blood pressure) was markedly abnormal.  The cost of this screening evaluation was reported to be $130 per athlete, or $102,050 total.

 

The Findings

The screening evaluation was abnormal in 112 athletes (14.3% of the total):

  • 5.1% due to abnormal, “pathologic” ECG findings
  • 4.7% because of abnormal physical examination
  • 1.6% due to a “positive” personal or family medical history
  • 4.1% because an athlete was at “high risk” for atherosclerotic heart disease

Each of these athletes then underwent subsequent, more detailed testing to shed more light on the athlete’s cardiac circumstance and to determine if a true cardiac problem was present.  These tests included, among others:  echocardiogram (an ultrasound examination of the heart’s structure and function); stress test; 24-hour blood pressure monitoring; 24-hour Holter monitoring (of the ECG, continuously, to evaluate for arrhythmias); cardiac MRI; coronary angiography; and tilt testing.  A total of 194 such tests were performed and these additional tests had a total cost of $54,556.

In the end, a new, previously unsuspected cardiovascular problem was identified in 22 (or 2.8% of the 785) athletes:

  • 8 with hypertension
  • 5 with mitral valve prolapse and at least moderate mitral regurgitation
  • 3 with biscuspid aortic valve (2 with moderate aortic regurgitation and 1 with mild aortic stenosis)
  • 1 with mild pulmonary valve stenosis
  • 1 with vaso-vagal syncope
  • 1 with Wolf-Parkinson-White syndrome
  • 1 with hypertrophic cardiomyopathy (HCM)*
  • 1 with significant coronary artery disease and “old” myocardial infarction*
  • 1 with abdominal aortic aneurysm*

This group included 19 men and 3 women.  Of these 22 athletes with newly diagnosed cardiac conditions, 3 were deemed ineligible to participate in their sports because of unacceptably high risk of cardiovascular events (indicated by an asterisk, above).  Each of the 3 athletes who were deemed ineligible for sports activities were identified by an abnormal ECG during the initial screening.

The other 90 athletes with an abnormal initial screening evaluation were “cleared” on the basis of their subsequent testing.  We might refer to these athletes as the “false-positives”–those with an abnormal initial screening evaluation, but no real cardiovascular problem.

Interestingly, no diagnosis of coronary artery disease (CAD) resulted from the 76 exercise stress tests that were performed.

 

The Investigators’ Conclusions

The authors reached 4 main conclusions:

  1. The screening program was effective in identifying a small, but significant, number of athletes with significant cardiovascular conditions that required treatment or monitoring.
  2. The screening program was effective in identifying a very small number of athletes in whom continued participation in sports activities was thought to be dangerous.
  3. Inclusion of the ECG in the initial screening evaluation was important.
  4. The screening program was practical and the costs were reasonable.

 

My Thoughts

This study provides some pertinent data to help frame our discussions about cardiovascular screening for adult, recreational athletes.  The study population here appears to be typical in many regards, and I suspect the study results can reasonably be generalized to athletic populations far beyond Switzerland.

Adult, recreational athletes are not typically bound by the mandatory pre-participation cardiac screening programs that are used for young, competitive athletes.  They have to make their own decisions in this regard.  They must decide whether “getting checked out” is worth the expense.  Athletes might have a variety of relevant questions.  How likely am I to discover a previously unrecognized cardiac problem–particularly if I don’t have any symptoms?  What are the chances that I could be a false-positive–with the burden of additional diagnostic testing to sort things out?  What will this all cost?

Each of these questions now has an answer.

With regard to the first question, there is an approximately 3% chance of identifying a previously unrecognized, unsuspected, and presumably asymptomatic, cardiovascular condition.  On t op of that, there is an approximately 4% chance of identifying a high risk profile, based on risk factors, that deserves close follow-up.  And finally, there is an approximately 0.4% chance (3 athletes among 785) of identifying a serious cardiovascular condition that places an athlete at undue risk of sudden cardiac death during exercise.  It’s not clear from the study whether these risks are similar for men and women.

The second question also has an answer.  The chance of a false-positive, using this particular screening evaluation, was approximately 11.5% (90 athletes among 785).  That is a fairly large number.  Recall that each of these athletes required additional diagnostic testing–at additional cost–to establish that they didn’t actually have a problem after all.

The third question has also been answered–at least in Switzerland.  The average cost of the screening program–initial evaluation plus the costs of additional testing that was needed–was $199 per athlete.  The cost for the 663 athletes who had a normal screening evaluation was only $130.  Obviously, the costs for the remaining 122 athletes, with an abnormal screening evaluation, and who required additional diagnostic testing, were greater.  All of these costs would be much higher in the United States, I suspect, and this issue is compounded by the fact that most health insurance policies don’t cover screening evaluations such as these.  For many American athletes, these expenses would be out-of-pocket.

At any rate, this new information will be helpful as athletes have discussions with their physicians about whether or not to pursue cardiac screening.

Those are my thoughts about the issue from the athlete perspective.

From the physician perspective, I think it’s important to note that all of the stress testing results were normal.  These are expensive tests.  We need to keep in mind that the pre-test probability of an abnormal finding in an asymptomatic population of exercisers is extraordinarily low.  Perhaps, it’s best to think twice before ordering a stress test in this situation.

And finally, from the perspective of the event organizer, the prevalence data here is enlightening.  Governing bodies and race directors should be aware that several percent of participating athletes will have unsuspected cardiovascular problems, including 0.4% who are at high risk of sudden cardiac death during exercise.  These numbers should inform safety planning efforts.  It shouldn’t be surprising that we have a small number of cardiac emergencies and even fatalities in recreational competitions involving adult athletes.

 

Reference:

1.  Menafoglio A, Di Valentino M, Porretta AP, et al.  Cardiovascular evaluation of middle-aged individuals engaged in high-intensity sport activities:  implications for workload, yield and economic costs.  Br J Sports Med 2014;01-6.  doi:10.1136/bjsports-2014-093857.