While patients with HCM may develop heart failure at any age, only a minority ever experience severe heart failure—and more than 25% of patients with HCM live beyond the age of 75.8 Overall, adults with HCM have a 1% annual mortality rate, which is similar to that of the general adult population in the United States. For adults with HCM who have had an episode of cardiac arrest or have more than 1 major risk factor for SCD (TABLE 1), the annual mortality rate climbs to 6%.1
TABLE 1
HCM: Assessing risk of sudden cardiac death6,21,33
| Major risk factors Prior cardiac arrest* Unexplained syncope Family history of SCD Left ventricular wall thickness ≥30 mm Abnormal BP response to exercise Nonsustained spontaneous ventricular tachycardia |
| Possible risk factors LVOTO Late gadolinium enhancement on MRI Myocardial ischemia Specific troponin T and I mutations Intense physical exertion Atrial fibrillation |
| *Prior cardiac arrest is the most predictive of any major factor. |
| BP, blood pressure; HCM, hypertrophic cardiomyopathy; LVOTO, left ventricular outflow tract obstruction; MRI, magnetic resonance imaging; SCD, sudden cardiac death. |
The sports physical: Frustratingly “normal”
The mainstay of screening for HCM and other cardiac abnormalities associated with exertional SCD is the preparticipation physical examination, coupled with the medical history. The physical exam itself, however, is an insensitive screening tool for this condition. That’s because most patients with HCM have nonobstructive disease, meaning there is no murmur to be heard.1 Even among HCM patients with LVOTO, the murmur may be difficult to detect. Typically, it can be heard only when the patient stands or performs the Valsalva maneuver, movements that decrease preload. Clinicians who manage to detect the murmur generally describe it as a late-systolic ejection murmur best heard at the left sternal border radiating to the aortic and mitral areas, but not into the neck.9
Resting pulses, too, are typically normal in a patient with HCM/LVOTO, although “water hammer” and double-peak pulses may be present.10 At high levels of exertion, such patients may exhibit decreased peripheral pulses and an ominous decrease in systolic blood pressure.
It’s important to realize, however, that such findings are the exception. Because most patients with HCM have normal physical exams, the medical history plays a particularly important role in pinpointing patients at risk.
It’s time to tweak your preparticipation questionnaire
In recent years, efforts have been made to improve preparticipation questionnaires.11 Despite these efforts, only 17% of the preparticipation evaluation forms currently used by US high schools contain all the recommended screening elements.12 Validated screening questions are recommended by the American College of Cardiology (ACC), American Academy of Family Physicians, and other major organizations (TABLE 2). These 9 questions address symptoms triggered by exertion, such as chest pain, palpitations, syncope, or near syncope; history of heart murmur or need for an electrocardiogram (EKG); and family history of unexplained sudden death or premature heart disease.13 Further evaluation is critical if the answers indicate a suggestive patient or family history. (See “The sports physical: Should EKG be mandatory?”.)
TABLE 2
Screening for HCM: 9 questions you need to ask13
| 1. Have you ever passed out or nearly passed out during exercise? |
| 2. Have you ever passed out or nearly passed out after exercise? |
| 3. Have you ever had discomfort, pain, or pressure in your chest during exercise? |
| 4. Does your heart race or skip beats during exercise? |
| 5. Has a doctor ever told you that you have a heart murmur? |
| 6. Has a doctor ever ordered a test for your heart (for example, EKG, echocardiogram)? |
| 7. Has anyone in your family died for no apparent reason? |
| 8. Does anyone in your family have a heart problem? |
| 9. Has any family member or relative died of heart problems or of sudden death before age 50? |
| EKG, electrocardiogram; HCM, hypertrophic cardiomyopathy. |
The sports physical: Should EKG be mandatory?
Because both the physical exam and medical history are imperfect screening modalities, some clinicians have proposed the 12-lead EKG as an additional HCM screening tool. In the United States, the proposal is controversial, but the debate has intensified as a result of Italy’s experience: a 90% reduction in SCD following the implementation of a national EKG screening program for young athletes.37
Advocates in the United States cite the success of the Italian model and the lack of sensitivity in the standard history-physical HCM screening. Indeed, a retrospective study of US athletes who died suddenly showed that only 3% had been identified as having HCM during the traditional preparticipation screening, and none had been disqualified.38 Opponents of universal EKG screening point to the large number of potential candidates—approximately 12 million young people, ranging in age from adolescence through college, would need to be screened. Opponents also cite differences in the Italian and American populations; cost-benefit considerations; the large number of false-positive EKGs expected (10% to 15%); and most importantly, the lack of medical personnel to perform and interpret the EKGs.39 While advances in EKG technique may minimize false-positive readings and changes in the health care system may eventually create an environment more favorable to uniform screening procedures, current recommendations for preparticipation screening call for history and physical alone.