A 16-year-old male was seen for routine physical exam for sports participation clearance. States he feels well today and past medical history is non-contributory. Upon exam, all systems are within normal limits with the exception of a cardiovascular murmur, loudest over the apex, grade II/IV systolic. Patient denies current or previous cardiac symptoms. Denies family history of cardiovascular disease or sudden cardiac death.
The recommendation in this case should be to withhold sports clearance pending a thorough cardiovascular workup, to initially include electrocardiogram, chest x-ray, and potentially echocardiogram (with subsequent referral to cardiology) to help rule out cardiomyopathy (National Heart, Lung, and Blood Institute, 2011). Suspicion is particularly high for hypertrophic cardiomyopathy, which often presents with a grade II-III/VI systolic murmur, heard loudest over the apex of the heart (National Heart, Lung, and Blood Institute). If patient does suffer from cardiomyopathy, sports may be contraindicated at the present time. Cardiology may consider interventions such as surgery (if severe), implantable devices, and/or medications such as beta blockers or calcium channel blockers (American Heart Association, 2014b).
Cardiomyopathy is a disease of the myocardium, characterized by abnormal muscle fibers (those which are responsible for contracting with each heartbeat) (Huether and McCance, 2012). There are several different types of cardiomyopathies, including dilated, restrictive, and hypertrophic (Huether and McCance, 2012). While all three can cause sudden cardiac death during vigorous exercise, hypertrophic cardiomyopathy in particular is implicated in a large number of sudden cardiac deaths during exercise each year (American Heart Association, 2014a). This type of cardiomyopathy is characterized by abnormal thickening of the septal wall, which inhibits ventricular outflow, particularly during vigorous exercise, causing conduction abnormalities such as arrhythmias (Huether and McCance, 2012). The cardiomyopathies can be completely asymptomatic or symptomatic; and can be acquired (due to illness or disease), idiopathic, or inherited.
A fairly large percentage of cardiomyopathies are inherited, in particular the hypertrophic subgroup (American Heart Association, 2014a), and can have a large impact on diagnosis. Because it can be silent, with an asymptomatic presentation that can remain undiagnosed over an entire lifespan (American Heart Association, 2014a), this may lead to lack of awareness within families of any genetic history, as may be the case with this particular patient. His history was non-contributory for sudden cardiac death or cardiovascular disease, but given its silent nature, it is possible the disease still runs in this patient’s family. Lack of family history of the disease can create a false sense of security in the clinician, who may be tempted to clear the patient with no significant family history.
Diagnosis may also be improved with genetic testing. It can rule out an acquired or idiopathic diagnosis, allowing the clinician to focus on treating the disease itself, rather than looking for (and treating) an underlying cause. Identification of a genetic cause may also prompt evaluation of family members (such as siblings) and will allow awareness to be passed on to subsequent generations (National Heart, Lung, and Blood Institute, 2011).
Treatment of this patient may not be greatly impacted by a genetic diagnosis; there are standard treatments that are often employed based on the type and severity of the cardiomyopathy, regardless of cause (National Heart, Lung, and Blood Institute, 2011). However, acquired cardiomyopathy patients sometimes require additional treatment of the underlying disorder (National Heart, Lung, and Blood Institute, 2011). In this case, a genetic diagnosis would mean that the clinician would not have to continue to look for or treat an underlying disorder; he or she would focus on treating the cardiomyopathy itself with appropriate interventions.
American Heart Association. (2014a). Hypertrophic cardiomyopathy. Retrieved from http://www.heart.org/HEARTORG/Conditions/More/Cardiomyopathy/Hypertrophic-Cardiomyopathy_UCM_444317_Article.jsp
American Heart Association. (2014b). Prevention and treatment of cardiomyopathy. Retrieved from http://www.heart.org/HEARTORG/Conditions/More/Cardiomyopathy/Prevention-and-Treatment-of-Cardiomyopathy_UCM_444176_Article.jsp
Huether, S. and McCance, K. (2012). Understanding Pathophysiology. 5th ed. St. Louis, MO: Mosby, Inc.
National Heart, Lung, and Blood Institute. (2011). How is cardiomyopathy diagnosed? Retrieved from http://www.nhlbi.nih.gov/health/health-topics/topics/cm/diagnosis