Hypertrophic cardiomyopathy (HCM) is one of the most common genetic heart diseases in the United States, affecting approximately 600,000 to 700,000 people. In many cases, patients remain unidentified. This, in part, may explain why few cardiology practices have the opportunity to evaluate HCM patients nationwide. In 2003, the American College of Cardiology (ACC) and European Society of Cardiology created an expert consensus panel on HCM. The ACC and the American Heart Association (AHA) revisited the topic with the publication of guidelines in the December 13, 2011 issues of Circulation and the Journal of the American College of Cardiology.

“HCM has become a highly treatable disease thanks to new management strategies, but many physicians are still challenged with managing it,” says Barry J. Maron, MD, who co-chaired the ACC/AHA guideline update writing committee. “We took this opportunity to clarify the most important diagnostic and management strategies. Many of the recommendations in the 2011 guidelines are similar to those in the 2003 consensus document, but newer data have provided a better understanding of these recommendations, particularly in the areas of prevention of sudden death and genetic testing.”

Hypertrophic Cardiomyopathy Recommendations

According to the ACC/AHA guidelines, treatment of patients with HCM must be individualized and requires an understanding of the complex pathophysiology and natural history of the disease. According to Dr. Maron, the three areas of greatest importance are use of prophylactic defibrillators, management of outflow tract obstruction, and application of genetic testing. Implantable cardioverter defibrillators (ICDs) for the prevention of sudden cardiac death are the only treatment known to prolong life in this disease, says Dr. Maron. The generally agreed upon indications for considering prophylactic ICDs (Figure) include the presence of at least one of the following:

Prior unexplained syncope.
Massive left ventricular hypertrophy.
Family history of sudden death due to HCM.
Multiple and repetitive nonsustained ventricular tachycardia on 24-hour ambulatory (Holter) ECG.
Hypotensive blood pressure response to exercise.

“The ACC/AHA guidelines make it clear that the gold standard treatment for most patients with drug-refractory symptoms and outflow obstruction remains surgical septal myectomy,” Dr. Maron explains. “Alcohol septal ablation is an acknowledged alternative in select patients.”

Genetic testing in HCM represents a potentially powerful diagnostic strategy that has emerged during the past decade and is now commercially available. “The most appropriate use of genetic testing is for evaluating family members for the disease-causing mutation, particularly those without left ventricular hypertrophy,” Dr. Maron adds. “Genetic testing, however, has no role in predicting prognosis.”

Participating in Sporting Activities with HCM

HCM has been identified as the most common cause of sudden death in young people and those engaged in competitive sports. The generally accepted recommendation has been to disqualify HCM patients from most competitive, intense sports. “However, many physical activities outside of the competitive arena are acceptable for patients with HCM,” adds Dr. Maron (Table). “The general recommendation is to avoid a sedentary lifestyle but also to avoid activities that require sprinting or raising the heart rate abruptly, systematic training for competition, or situations in which patients cannot easily withdraw themselves should they become aware of potential HCM symptoms.”

Special Considerations with Atrial Fibrillation

Atrial fibrillation (AF) affects about 25% of patients with HCM, making it the most common sustained arrhythmia in the disease. It is four times more common among patients with HCM than in the general population. “Treatment of AF in patients with HCM is similar to that of patients with other diseases,” adds Dr. Maron, “particularly prevention of embolic stroke with anticoagulation.”

HCM is compatible with normal life expectancy, with many patients never requiring treatment or incurring any significant disability. For those who experience important disease complications—which is the minority—a number of management considerations and treatment interventions have been proven effective. “Although more knowledge is needed about HCM,” says Dr. Maron, “we anticipate that much will be learned in the future. Nevertheless, the good news is that HCM is a disease that can now be managed better than it has in the past, often with a favorable prognosis and with normal longevity and quality of life.”

References

Gersh B, Maron B, Bonow R, et al. 2011 ACCF/AHA guideline for the diagnosis and treatment of hypertrophic cardiomyopathy: a report of the American College of Cardiology Foundation/American Heart Association Task Force on Practice Guidelines. Circulation. 2011;124:2761-2796. Available at http://dx.doi.org/10.1161/CIR.0b013e318223e2bd.

Gersh B, Maron B, Bonow R, et al. 2011 ACCF/AHA guideline for the diagnosis and treatment of hypertrophic cardiomyopathy: a report of the American College of Cardiology Foundation/American Heart Association Task Force on Practice Guidelines. Am Coll Cardiol. 2011;58:2703-238.

Maron B, Yeates L, Semsarian C. Clinical challenges of genotype positive (+)-phenotype negative (-) family members in hypertrophic cardiomyopathy. Am J Cardiol. 2011;107:604-608.

Maron B, McKenna WJ, Danielson GK, et al. American College of Cardiology/European Society of Cardiology clinical expert consensus document on hypertrophic cardiomyopathy. J Am Coll Cardiol. 2003;42:1687-1713.