An important article appeared in this week’s edition of Circulation, one of the American Heart Association (AHA) medical journals. Dr. Kimberly Harmon and her colleagues at the University of Washington wrote an article entitled, “Incidence of Sudden Cardiac Death in National Collegiate Athletic Association Athletes.”
We know that sudden cardiac death (SCD) is a sad, but thankfully uncommon, event among student athletes. As I’ve said before, these events often receive sensational attention in the popular press when they occur. Unfortunately, it has been difficult to get a handle on the number of such events because there is no required reporting of such events. As a result, various investigators have estimated the frequency of SCD to be anywhere from 1 per 23,000 athletes to 1 per 300,000 athletes.
In the newly published article, Dr. Harmon reviewed the records from the National Collegiate Athletic Association (NCAA) that pertained to student athletes who competed from 2004 through 2008. This represented 300,835 athletes aged 17 through 23 years who competed in 40 sports in all three NCAA divisions. In total, there were 1,969,663 athlete participation-years.
The investigators found 273 deaths during that period. The majority of these deaths were not sports-related, with a variety of causes such as accidents, suicides, homicides, and drug overdoses. The cause of death was medical in 80 cases and, among these, the cause was cardiac in 45. Thus, the rate of SCD in NCAA athletes works out to be 1 per 43,770 per year.
The rate of SCD was different for various sports, with the higest rates for the following sports:
Basketball: 1 per 11,394 per year
Swimming: 1 per 21,293 per year
Lacrosse: 1 per 23,357 per year
Football: 1 per 38,497 per year
Cross country: 1 per 41,695 per year.
There are several important implications of the study:
1. We should expect similar rates of SCD for closely younger (high school) and older (adult), non-student athletes. Both of these groups have many more participants than the group of college athletes that was studied.
2. Knowing that an EKG detects upwards of two-thirds of hidden cardiovascular diseases in athletes, it may be prudent to include an EKG as part of a pre-participation physical examination for athletes in the higher-risk sports.
3. Knowing the higher-risk sports may show athletic departments and event planners where to best deploy resources such as automatic external defibrillators (AED’s) and on-site health professionals to treat potential victims of SCD.
Today we’re talking about commotio cordis, a surprising (but not rare) cause of sudden death in athletes. The term commotio cordis comes from Latin, and means “agitation of the heart.” This is apt.
A typical scenario might unfold like this….
A teenage pitcher on a high school baseball team makes his pitch and the batter hits the ball back directly at the pitcher. The ball strikes the pitcher in the front of the chest, the pitcher falls to the ground….and doesn’t get back up. Bystanders react slowly, but tend to the pitcher and find that he is unconscious. It takes a while for the bystanders to realize the gravity of the situation and they eventually begin CPR when they realize that there is no pulse and the pitcher is not breathing. Eventually, somebody thinks to call 911 and EMS providers arrive on the scene some 15 minutes after the incident. They discover that the patient has an arrhythmia called ventricular fibrillation, but despite attempts at defibrillation (shocking the patient), the pitcher cannot be resuscitated and dies. We hear about the episode in a short report in the local newspaper the next day.
What is Commotio Cordis?
We use the term commotio cordis to refer to an incident where an individual is struck by an object in the chest, causing a fatal arrhythmia. This is a different situation that when an individual suffers major trauma (eg, motor vehicle accident) with significant chest trauma and there is evidence of significant injury (eg, contusion) to the heart. In the case of commotio cordis, the trauma is seeminly minor.
It turns out that commotio cordis is probably the second most common cause of sudden cardiac death in young athletes; only hypertrophic cardiomyopathy is a more common cause.
Who Gets Commotio Cordis?
Most instances of commotio cordis occur in young male athletes who are struck in the chest by a projectile such as a baseball. Direct blows to the chest, as in karate or other martial arts, may also be a cause. Other sports where this condition has been reported include softball, ice hockey, football, and lacrosse.
This condition historically received little attention in the broader public media or scientific community. Recently, though, there was the formation of the U.S. Commotio Cordis Registry to keep track of victims. To date, more than 210 cases have been reported.
Among patients in the U.S. Registry, the majority of athletes with commotio cordis were between 10 and 25 years old; 26% were younger than 10 years of age, and only 9% were older than 25 years old.
Almost 50% of commotio cordis events occur during competitive sporting events. The remainder occur, about equally, in daily activities or in recreational sporting activities.
What Actually Happens to the Heart?
In victims of commotio cordis, the impact of a blunt object on the anterior chest wall leads to ventricular fibrillation, a disorganized rhythm of the ventricles that results in ineffective pumping of the heart, and a marked fall in the blood pressure. We’ve learned from investigations in animal models that the susceptibility to ventricular fibrillation occurs during a very specific, very short period (perhaps just 20 msec) during the cardiac cycle that corresponds to the initial upstroke of the T-wave on the ECG.
Like the photo at the top, it’s like hitting the bullseye, but with a baseball or other flying object. The impact on the anterior chest wall must occur at just the precise moment to produce the fatal arrhythmia.
What’s the Treatment?
Commotio cordis is usually fatal. With increasing attention paid to this condition, though, the survival rate has increased from about 15% to about 35% over the past decade.
The only effective treatment for invididuals with ventricular fibrillation due to commotio cordis is prompt defibrillation. We know that survivors have received prompt CPR and defibrillation within the first few minutes after collapsing. The survival rate may be less than 5% for victims in whom CPR/defibrillation is delayed more than 3 minutes.
These statistics point to the importance of bystander CPR and the availability of automatic external defibrillators (AEDs) for use by bystanders before trained medical personnel can arrive on the scene.
How Can We be Better Prepared?
Efforts to reduce the frequency (and mortality associated with) commotio cordis are focused in 3 areas: 1) prevention, 2) better awareness, and 3) prompt, effective treatment.
Because of the variety of mechanisms that are responsible for commotio cordis, it’s unlikely that athletes could be told to avoid all situations in which commotio cordis might occur. On the other hand, athletes CAN be instructed to turn the chest when a ball is heading toward them, so that it strikes somewhere other than the anterior chest. And, of course, strict attention can be paid to wearing chest protectors for goalies, baseball catchers, etc.
Better awareness about commotio cordis, particularly among athletes and coaching staffs, might help promote quicker recognition of the problem–and then institution of prompt treatment with CPR and defibrillation. Too often now, bystanders don’t recognize the life-threatening nature of an athlete’s collapse after being struck, and treatment is unnecessarily delayed.
The report from the 36th Conference on Eligibility Recommendations for Competitive Athletes with Cardiovascular Abnormalities made several recommendations about commotio cordis:
1. Age-appropriate safety baseballs are recommended for use in children up to 13 years of age.
2. Although chest wall protectors may prevent traumatic injury in goalies and baseball catchers, insufficient evidence is available to recommend universal use of commercially available chest barriers for all participants in sports, specifically to prevent commotio cordis events.
3. AED’s should be available within 5 min after participant collapse at sporting events.
4. Survivors of a commotio cordis with ventricular fibrillation should undergo a thorough cardiac evaluation, including at least 12-lead ECG, ambulatory Holter monitoring, and echocardiogram.
5. Because data are lacking with regard to the susceptibility for recurrent events, eligibility for returning to competitive sports in survivors is at present a decision left to individual clinical judgment.
At the Ironman Canada triathlon last August, Canadian triathlete Walter Eugene Wiwchar became distressed during the swim portion of the race and died.
This article in the online edition of the Penticton (British Columbia) Western News chronicles the day’s events. The article does not completely describe the sequence of events, but apparently Wiwchar was rescued from the water near the completion of the swim portion when he indicated he was in distress. By the time he was rescued, he was unconscious.
The article reports that an autopsy showed that the cause of death was drowning, but that Wiwchar had the condition called aortic dissection–a tearing apart of the layers of the portion of the aorta that carries blood away from the heart and to the rest of the body. The article speculates that the physical distress caused by the aortic dissection probably led, in turn, to the drowning.
We’ve mentioned aortic dissection previously here at the blog, in relation to individuals (like Flo Hyman) who have the Marfan Syndrome. These individuals are particularly predisposed to the problem of aortic dissection. It turns out, though, that most individuals who suffer aortic dissection do not have Marfan Syndrome. It turns out that nearly all individuals with aortic dissection have high blood pressure (that is poorly controlled).
The consequences of aortic dissection are always serious and often fatal. Even with immediate medical attention (and possible surgery to correct the problem), many affected patients die. The most obvious key to prevention of this problem is vigorous treatment of high blood pressure. This is particularly true for athletes.
In a previous post, “Sudden Death and Cold Weather Marathon,” I talked about the unfortunate death of an athlete who was competing in our local Mississippi Blues Marathon a couple weeks ago. There’s been a lot of discussion in my circle of friends about the man’s death and I’ve gotten many questions such as “Why did he die?” I thought I’d take the opportunity to talk a little bit about sudden cardiac death (SCD) in general, what we’ve learned about treating patients who have sudden death, and what lessons might apply to athletes in particular.
The Problem of SCD
Last week, the American Heart Association (AHA) issued a policy statement, published in their journal Circulation, entitled “Regional Systems of Care for Out-of-Hospital Cardiac Arrest.” In the United States, there are approximately 295,000 individuals who suffer out-of-hospital cardiac arrest (OOHCA) each year. Of those, only 7.9% are fortunate to be treated and eventually discharged alive from a hospital. It’s sobering. And because it’s so sobering, the AHA and other organizations devote many resources to improve upon these results.
When we say that individuals have suffered OOHCA, we mean that they have developed a fatal arrhythmia (abnormal heart beat) in the heart, usually ventricular tachycardia or ventricular fibrillation (abnormal rhythms of the pumping chambers). With that type of arrhythmia, the heart no longer pumps blood. Within minutes, the vital organs of the body (particularly the brain) begin to suffer irreversible damage. And the only effective treatment is to restore the heart rhythm to normal in a timely fashion.
The History of Treatment for SCD
We’ve known for more than 250 years that cardiopulmonary resuscitation (CPR) could be used to help individuals who had suffered cardiac or respiratory arrest. As early as 1740, the Paris Academy of Sciences officially recommended mouth-to-mouth resuscitation for drowning victims. In 1903, Dr. George Crile reported the first successful use of external chest compressions in human resuscitation. In 1963 the AHA endorsed CPR and formed a Committe on CPR chaired by Dr. Leonard Scherlis. And in 1966, the National Research Council of the National Academy of Sciences convened an ad hoc conference on CPR….and led to the recommendation of standardized training and performance standards for CPR (chest compressions and rescue breathing).
Beginning in the 1950’s we learned that SCD is typically caused by a fatal arrhythmia and that defibrillation (a shock) could be used to restore the normal heart rhythm. Initially, this was available only in hospitals, but by the 1970’s defibrillation could be provided by emergency medical personnel such as paramedics or emergency medicine technicians (EMTs). Continued advancements in technology have allowed for the development of the automated external defibrillator (AED), a device which can record the heart rhythm, interpret the rhythm, and automatically administer a shock of the appropriate type to try to restore the normal heart rhythm. With the advent of the AED, it has become possible for non-medical people to provide life-saving defibrillation at the scene of a cardiac arrest.
As a public health measure, AED’s have been recommended and placed in many locations where SCD might occur with increased frequency….airports and other transportation centers, large shopping malls, sports complexes, large industrial sites, golf courses, gyms/health clubs, community centers, etc.
The AHA now sponsors a variety of courses in basic life support, including techniques of CPR and use of the AED. The various courses have target audiences that range from fully trained healthcare providers to entirely non-medical people. Many healthcare organizations require their employees to be trained in basic life support, but most graduates of basic life support training programs are actually non-medical people.
SCD in Athletes
We’ve talked a little about SCD in athletes previously here at the blog. Indeed, SCD is the most common cause of death in exercising athletes. And this unfortunate event occurs approximately every 3 days in the United States.
Dr. Jonathan Drezner and his colleagues at the University of Washington recently reported an experience in 9 young athletes who suffered sudden cardiac arrest. All 9 had a witnessed collapse and received bystander CPR immediately. A defibrillator was available and used in all 9–within 1.6 minutes when provided by a trainer and within 5.2 minutes when provided by an emergency responder (EMS). Still, only 1 out of 9 athletes who suffered sudden cardiac arrest survived. This experience is typical.
In the world of endurance sports for adult participants, the situation is complicated because of the large geographical area over which these events are conducted. A 5K run doesn’t seem so far, but a 26.2 mile marathon or a 140.6 mile Ironman distance triathlon takes the participants far from the immediate reach of medical volunteers or any available AED’s or other defibrillators.
Successful treatment of athletes who suffer suddenc cardiac arrest depends on:
1. Prompt recognition that cardiac arrest has occurred.
2. Early bystander CPR.
3. Early defibrillation.
4. Early advanced life support provided by the EMS system.
All four of these components are necessary in order to save the life of an athlete who suffers cardiac arrest. So….when we look back at the issue of “why” an athlete dies during a marathon, the explanation is often found right here.
1. As a service to your fellow athletes and community as a whole, learn CPR. Contact the AHA and find an appropriate course in your area.
2. Take the time to check at your local schools and at your local fitness centers to be sure that an AED is available and that on-site personnel are trained in CPR and the use of the AED. These folks may someday be needed to save your life or the life of your child.
3. If you’re involved in the planning of endurance sporting events or organized training sessions for endurance athletes, take the time to develop an emergency response plan. Don’t be caught off-guard if sudden cardiac arrest occurs.