Hypertrophic Cardiomyopathy

Transcription

1 Hypertrophic Cardiomyopathy Injuries in sports are going to happen. There is nothing we can do to change them. We can simply work to prevent as many of them as we can while reducing the life- long effects of injury when they do occur. Unfortunately some injuries are catastrophic and may even lead to death. Additionally, catastrophic injuries can be the result of a missed symptom of a general medical condition. In this paper, the author will attempt to enlighten readers to a series of conditions known most frequently as sudden cardiac death. A specific emphasis will be placed on hypertrophic cardiomyopathy (HCM) however sudden cardiac death and the controversy that surrounds the entire climate of testing and participation shall be examined. A study conducted by Maron et al looked at sudden death in Minnesota and found that 134 of 158 deaths were cardiovascular in nature (1). Sudden cardiac death is a leading cause of death in youth athletics. While concussions have led the media frenzy that is athletic safety in the last few years, concussions have not been a killer as often as one may believe. Concussions are a serious matter and that point should not be argued. However it is important to note that sudden cardiac death needs to become a major concern in the United States and right now it does not appear to get the attention it needs. There are a lot of variables that come into play for why this may be the case. But what causes sudden cardiac death and what can be done to prevent it? There are many causes of sudden cardiac death. Some of these conditions can include hypertrophic cardiomyopathy, arrhythmogenic right ventricular

2 cardiomyopathy, left ventricular noncompaction, and idiopathic dilated cardiomyopathy (2). In this article hypertrophic cardiomyopathy will be the focus as it leads all others in its rate of fatality. Hypertrophic cardiomyopathy is a heart condition that affects the left ventricular wall and an individual is most often asymptomatic until tragedy strikes. The condition is caused by an underlying genetic mutation of sarcomeric proteins which can cause non- dilated left ventricular cavity and diastolic dysfunction. The best way to identify HCM is through the use of an electrocardiogram (ECG). Tell- tale signs of HCM on an ECG can consist of inferolateral T- wave inversions, ST depression, pathologic Q waves, left axis deviation, left atrial enlargement and conduction delays (3). Very few clinical cases of HCM will result in a normal ECG however an abnormal ECG cannot be the only tool used to diagnose the condition as there are other conditions that may cause the abnormality as well. The ECG is a front- line tool often used to screen patients and if warranted these patients would then be referred to a cardiologist for further evaluation. If one is suspected of having HCM after an ECG, then the next step is an echocardiogram to determine the size of the left ventricular walls. The common cut- off is 15mm, but it is important to also rule out other conditions such as hypertension that may be causing this thickness. This shows the importance of a thorough medical screening because there are multiple conditions that can cause some of the signs and symptoms so the medical professionals must work hard to eliminate other potential causes before diagnosing a condition.

3 The importance of a thorough medical screening prior to athletic participation cannot be understated. Unfortunately, in the United States, there is no single standard for a pre- participation examination. Instead, each state and in some cases each school district determines what is considered to be important in the screening process. The American Heart Association recommends a 12 point health screening in an attempt to better understand the individual s family history. This screening is often including in the pre- participation examination paperwork for athletes, but its importance must be stressed so the athlete and his/her parents spend the time to accurately and truthfully answer the questions. This screen asks questions about personal history such as chest pain with activity, unexplained fatigue with exercise, heart murmur, high blood pressure, and fainting as an individual. From a family history perspective, questions such as death from heart disease and specific knowledge of any cardiac conditions in family members. The last section includes the physical examination looking for heart murmurs, narrowing of the aorta, Marfan s Syndrome, and blood pressure. The Illinois High School Association s physical form must be completed each year and it includes 12 questions about heart health history. Additionally, auscultation of the heart by the physician is required. Recommendation for additional cardiac evaluation is made for any abnormality present. Other states and even specific school districts may require a different form with a completely different process. The country of Italy has mandated ECG in mass screenings since the 1980 s and they have reduced their fatality rate due to HCM from 3.6 per 100,000 individuals to 0.4 per 100,000(4). That is a great improvement! But as O Connor continues to discuss, there are many flaws with the idea

4 that this massive screening could efficiently translate to similar success in the United States. The ethnic considerations, as mentioned, are one difference between the two countries. Papadakis et al presents additional insight into this idea that ethnicity may complicate matters into evaluating and diagnosing individuals with various heart conditions (5). Adaptations for various individuals around the world can complicate the screening process because one symptom may actually mean different things based on the individual s ethnicity. O Connor states that the study completed in Italy was comprised of mostly males and most of them were Caucasian. In the United States, it would be much more difficult to accurately portray each person s ethnicity due to the multi- ethnic population. Also, further research has shown that the United States already possess a fatality rate similar to that of Italy without ECG screening. This calls into question the need to mandate this screening at additional expense? Completion of the ECG also does not completely diagnose HCM or rule it out. Some positive findings that could be HCM on ECG could also fall under another condition commonly known as Athlete s Heart. Rowland mentions that athletes often demonstrate 14% increase in ventricular wall thickness compared to the nontrained subjects (6). He also calls into question the validity of HCM- related fatalities in sports with the belief that these athletes who are dying do not possess the signs found in the clinically- diagnosed HCM patient. Instead he believes that many of these deaths may be related to a fatal dysrhythmias with an exaggerated hypertrophy related to sports. Additional research in this area would be needed to further validate these beliefs. Another consideration with athlete s heart and HCM that must be addressed is the inability to distinguish

5 physiologic hypertrophy compared to pathologic hypertrophy based on anatomy alone. Often the patient may be diagnosed with HCM and then undergo a period of detraining which allows the ventricular wall to atrophy back to normal. This is where the diagnosis of Athlete s Heart comes into play. This can be a common trait found in athletes and possess much less risk of HCM. Additionally, high blood pressure can also cause thickening of the ventricular wall. This must be ruled out prior to diagnosis of HCM. Obviously an individual would much rather be diagnosed with high blood pressure rather than HCM because the high blood pressure is treatable and is not a contraindication for athletic participation. No single test has been yet identified to separate athlete s heart and HCM. Instead, a multitude of parameters such as gender, family history, left ventricular cavity and left atrial size, wall thickness change after deconditioning and oxygen uptake. HCM is characterized by a left ventricular wall thickness of greater than 13mm without other reason for this inflammation (2). HCM is not only a macroscopic structural condition, but also involved in microcirculation. Histological characterizations include myocyte disarray and abnormal intercellular connections. This expansion of the interstitial compartment is also the basis for the macroscopic changes associated with the wall thickness (7). The actual physical examination of a patient with HCM may come back completely normal. Due to the murmur s occurrence being related to the outflow tract obstruction, and the fact that it is often only present during exertion, this can be missed upon examination. These false- negatives are concerning because of the consequences that can be associated. This situation really puts the doctors in a tough situation,

6 however obviously it puts the patients in a life or death situation. Ng and Maginot suggest that the gold standard for diagnosing HCM is an echocardiogram however they identify previously mentioned obstacles remain at the forefront. Another concern of theirs is that approximately 75-95% of patients will present with an abnormal ECG (8). But what about the other 5-25%? How are those patients diagnosed? Those may be the cases where the athletes die before someone is able to realize there is actually something wrong with the individual. It is tragic that these deaths do occur, but it is good to know that these cases are few and far between. In the United States, it is estimated that 1 in every 200,000 athletes die from HCM. That is similar in nature to the study conducted in Italy. Many athletes die each year at a greater rate so there is reason to believe that SCD may not be as relevant as one would suspect. Gupta et al discuss the challenge of trying to identify the clinically silent but potentially deadly conditions efficiently within economically means. Unfortunately the American Heart Association s screening and basic physical examination is not very specific with regards to the identification of SCD. This calls into question the need for ECG in the pre- participation examinations. The challenging aspect is that there are approximately 12 million athletes to screen with a prevalence of around 0.3%. Of those who have died suddenly, only 3% of that group were identified as having an abnormality and none of them were restricted from participation. Ethical concerns and economical concerns have limited the American Heart Association and American College of Cardiology from recommending the use of a 12- lead ECG in all competitive athletes. One major obstacle is the cost of the screening and subsequent cardiac evaluation. In Italy,

7 this cost is borne by the National Health System, but in the United States such a mechanism is not yet in place. The expectation that each athletic organization would obtain the equipment and hire the trained personnel needed remains beyond the reach of reality. It is simply too expensive to even do the initial screening. Then, a determination must be made for who pays for the subsequent testing which, according to Gupta would be required in 30-40% of elite athletes (2). A large percentage of this group would be further evaluated and determined to have athlete s heart. So now there is money that many would consider to be wasted and many of these athletes would have their seasons and maybe even their careers ruined as a precaution. Obviously this will not bode well with the athletes or the teams, but the medical profession cannot choose to ignore these issues when they present themselves. It just appears that this testing is not yet valid enough for widespread use with the potential consequences of significant time being held out of exercise for what can turn out to be a minor condition. At the same time, obviously the risk of not diagnosing this serious condition carries much more catastrophic consequences. But the numbers do not quite provide evidence to mandate this screening in a widespread environment quite yet. Keeping all of this in mind, it is important that athletic organizations also prepare to respond in an emergency situation (9). It is crucial that the organizations have an emergency action plan (EAP) in place to respond to all emergencies. One component must include the response to cardiac events. Sport- appropriate medical coverage should be provided. For example, high- risk sports such as football and hockey should have a multi- layered sports medicine team whereas a sport such as volleyball may simply need

8 an athletic trainer. These EAPs should be coordinated between the school administration, the school s medical team, and local emergency medical services. If possible, the EAP should be rehearsed at least annually and it is beneficial to bring all groups in for training. An automated external defibrillator (AED) should be available and within easy access during all physical activities. The National Athletic Trainers Association and other groups have recommended that the AED be accessible within three minutes of a recognized cardiac event. Additionally coaches and administrators should be trained in CPR and the use of the AED in the event that there are no medical personnel available. This can also be beneficial so as to provide additional hands if there is a sole first responder available, as in many cases with single athletic trainers onsite. AEDs are simple enough to use that most coaches and teachers should be able to utilize the machine in case of an emergency. It is imperative that cardiac emergencies be treated in an urgent fashion and proper execution of the EAP is vital for an athlete to have a chance at survival. Sports injuries of many kinds take place each day around the world. While many of these may lead to minor inconvenience, minor disability, or lead to surgery, some may end up costing an athlete his/her life. In Sports Medicine it is important that the medical professions be ready for any situation whether it is a stubbed toe or an emergent cardiac event. HCM is associated with many sudden cardiac deaths each year and it is important that research continues in order to find better ways to diagnose the condition and treat it in an emergency situation. There is always room for improvement. The statistics may be low in the large scheme of things, but even one death is too many.

9 Sports are simply games and they should not be life or death situations. But that is exactly what can happen when a condition like HCM is misdiagnosed. Proper recognition is crucial, but must also be efficient and cost- effective in order for more organizations to adopt these processes moving forward.

10 Reference List 1) Maron BJ, Shirani J, Poliac LC, Mathenge R, Roberts WC, Mueller FO. Sudden death in young competitive athletes: clinical, demographic, and pathological profiles. JAMA. 1996;276: ) Gupta S, Baman T, Day SM. Cardiac health, part 1: pre- participation cardiovascular screening. Sports Health. 2009; Nov- Dec: ) Pelto H, Owens D, Drezner J. Electrocardiographic findings suggestive of cardiomyopathy: what to look for and what to do next. Current Sports Medicine Reports. 2013; ) O Connor DP, Knoblauch MA. Electrocardiogram testing during athletic preparticipation physical examinations. JAT. 2010;45(3): ) Papadakis M, Wilson MG, Ghani S, Kervio G, Carre F, Sharma S. Impact of ethnicity upon cardiovascular adaptation in competitive athletes: relevance to preparticipation screening. Br J Sports Med. 2012;46: ) Rowland T. Sudden unexpected death in young athletes: reconsidering hypertrophic cardiomyopathy. Pediatrics. 2009;123: ) Indermuhle A, Vogel R, Rutz T, Meier P, Seiler C. Myocardial contrast echocardiography for the distinction of hypertrophic cardiomyopathy from athlete s heart and hypertensive heart. Swiss Med Wkly. 2009;139(47-48): ) Ng B, Maginot KR. Sudden cardiac death in young athletes: trying to find the needle in the haystack. Wisconsin Medical Journal. 2007;106(6): ) Casa DJ, Almquist J, Anderson SA, Baker L, Bergeron MF, Biagioli B, et al. The inter- association task force for preventing sudden death in secondary school athletics programs: best practices recommendations. JAT. 2013;48(4).