Monday, February 1, 2016

From the Athlete’s Heart Mailbag

by Larry Creswell, M.D.

We invited readers to submit heart-health questions for Dr. Larry Creswell. Periodically through the coming months, Larry will devote his column to answering questions that should be of interest to triathletes and other endurance athletes. If you have a question, contact Larry by e-mail.


From Gavin: What type of cardiac screening/testing should you have done to determine if you are at risk for sudden cardiac death at a triathlon?

That’s a great question from Gavin, and one that I get frequently.

The answer to Gavin’s question has a couple parts. First, we need to know something about the causes of sports-related sudden cardiac death (SCD). And second, we need to do some sort of screening to determine if these causes are lurking in the otherwise healthy athlete with no symptoms of heart disease. In cardiology and sports medicine circles, we call this process pre-participation screening because ideally it’s accomplished before participating in exercise or sports.

What do we know about sports-related sudden cardiac death (SCD)?
For triathlon, there have been two reports on this issue -- a brief scientific report in 2010 by Dr. Kevin Harris on deaths during 2006-2008 and, more recently, a report by USA Triathlon that detailed deaths from 2003-2011. Both are worth reading.

From the USAT report, there were 45 fatalities over a 9-year period that included more than 22,000 events and more than 3-million participants. Five fatalities were due to bike crashes during a race. One fatality was actually a spectator. One fatality was a training camp participant. And one athlete, a cyclist, died of an unusual metabolic medical condition. For the remaining 37 athletes who died at a race, all had cardiac arrest. The majority of victims were men. The victims ranged in age from their 20s to their 70s. The majority of deaths occurred during the swim portion of a race, but a small number occurred during the bike portion, the run portion, or even after the completion of an athlete’s race.

The overall fatality rate worked out to 1 per 76,000 participants. If we exclude the traumatic deaths, the rate of sudden cardiac arrest was closer to 1 per 90,000 participants. So SCD is a rare event at a triathlon. To put the fatality rate into better perspective, if your local triathlon has 500 participants at each year’s race, you might expect to have 1 death every 180 years.

There can be two divergent takes on this problem. In one camp, there are those who suggest the problem is so uncommon that we shouldn’t waste our time on it. In another camp, there are those who suggest that even a single death is too many, and that we shouldn’t have recreational triathlons because of the danger. Gavin, though, is interested in the important middle ground: How can we participate safely?

What do we know about the causes of SCD? The autopsy information for triathlon-related deaths is not complete, but the majority of autopsies showed some sort of unsuspected heart condition -- mild to moderate hypertrophy (thickening) of the heart ventricle walls or a coronary artery abnormality. But there’s a fair amount of data about autopsy findings for athletes with sports-related SCD outside of triathlon, though. For younger athletes (less than 35 years old), we know that inherited (congenital) heart problems are most often the cause. The most frequent causes are hypertrophic cardiomyopathy (HCM), an anatomic abnormality of one of the coronary arteries, or long Q-T syndrome. Although these same inherited problems sometimes manifest for the first time in older athletes, coronary artery disease (CAD) is the most common abnormality found in older victims.

Gavin’s question is important because the individual triathlete wants to know how not to become the statistic. He wants to know if he unknowingly has one or more of these heart problems that predispose to the development of a sudden, fatal arrhythmia.

Pre-participation screening
How should you and your doctor go about looking for unsuspected heart conditions like the ones listed above? There are items in your past medical history, your family medical history, and your physical exam that have bearing.

From the medical history, we’re interested in knowing if the athlete has ever had:

  • Blacking out while exercising
  • Chest pain while exercising
  • Skipped heartbeats
  • A previous diagnosis of a heart problem
  • An EKG done for any reason
  • An unexplained seizure
  • Unusual shortness of breath.

If the answer to any of those questions is “yes,” then further investigation may be warranted.

For the family medical history, we ask if any close relative has had:

  • Early death from heart disease or an undetermined cause
  • Inherited conditions like HCM, Marfan syndrome, or long Q-T syndrome
  • Implantation of a pacemaker or internal cardioverter-defibrillator (ICD)
  • Unexplained fainting (syncope), seizure, or near-drowning.

If the answer to any of those questions is “yes,” then further investigation may be warranted.

The physical exam should be targeted at the heart and vascular system. An elevated blood pressure or physical findings such as a heart murmur, irregular heartbeat, bruit (abnormal sound heard with stethoscope over the carotid or other major arteries), features of the Marfan syndrome, discrepancy between the strength of the upper and lower extremity pulses should prompt further investigation.

Since older athletes with SCD are often found to have CAD, the visit should include an assessment of the known risk factors for CAD: high blood pressure, smoking history, (increasing) age, male gender, diabetes, abnormal serum lipid levels, and lack of exercise. Attention should be given to improving any of the modifiable risk factors.

Using all of this information, you and your doctor should make an overall assessment of your risk of having an underlying heart condition. For most athletes, that risk will be low, and no further investigation is needed. But if that risk is great enough - and, truthfully, only you can make that decision -- one or more additional diagnostic test may be appropriate.

An electrocardiogram (EKG or ECG) records the resting electrical activity of the heart. It can document the heart rate and detect any arrhythmia (such as atrial fibrillation), but here its importance is in identifying or suggesting problems like HCM or long Q-T syndrome. The EKG can also suggest a likelihood for WPW syndrome (a special type of arrhythmia that may occur infrequently) or evidence of previous injury to the heart because of CAD.

An echocardiogram is an ultrasound test where motion picture-like pictures are made of the heart using a transducer placed on the chest. This study accomplishes several objectives: a detailed look at the structure of the heart; an assessment of the function of the heart valves and the pumping function of the ventricles; and an estimation of the blood pressures in each of the chambers. The echocardiogram can document congenital abnormalities such as HCM, septal defects (“holes” in the heart), or valve abnormalities (such as bicuspid aortic valve).

Lastly, a stress test is sometimes warranted. This test can be performed several ways, but the most common is a treadmill test where the EKG and blood pressure monitored continuously during increasing exertion. The treadmill test can be combined with an echocardiogram to provide additional information. Regardless of the exact form, the stress test is designed primarily to look for indirect evidence of CAD.

Which, if any, of these additional diagnostic tests are useful or warranted depend upon an individual athlete’s risk profile and risk tolerance. At my blog, I recently hosted an Ask The Experts session, where experts in sports cardiology and sports medicine offered their approach to a variety of fictitious athlete scenarios. Check out that post to see how these tests might be applied.


Larry Creswell, M.D., is a cardiac surgeon and Associate Professor of Surgery at the University of Mississippi Medical Center in Jackson, Mississippi. In addition to his regular column on Endurance Corner, he maintains The Athlete's Heart blog to offer information about athletes and heart disease in an informal way and to encourage exchange and discussion that will help athletes build a heart-healthier lifestyle. You can contact him at lcreswell@umc.edu.
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