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Case of the week #11

Point of care ultrasound screening of HOCM and other causes of sudden cardiac death

While the diagnostic acumen of POCUS for many conditions is indisputable, its use in screening asymptomatic individuals is not well defined.

In this clinical scenario of a healthy athlete coming in for a physical and requesting an echo, POCUS may be extremely useful for its speed and ease of use in competent hands. In this particular case he had a normal echo. A complete echo on every student athlete however, is impractical and expensive. Can POCUS be the answer?

According to a review article in the Journal of the American College of Cardiology, the most common cause of sudden cardiac death in the U.S. is Hypertrophic Obstructive Cardiomyopathy (HOCM). One study that reviewed deaths in military recruits from 1977 through 2001 found that there were 126 sudden nontraumatic deaths and 86% of these were related to exercise. Half were a result of an identifiable cardiac abnormality, of those the most common abnormalities were anomalous coronary arteries, myocarditis, and HOCM. In National Collegiate Athletic Association (NCAA) athletes, a study showed that"increased risk has been found with male gender, black race, and basketball participation.The risk among male Division 1 basketball players has been estimated at more than 10 times that in the overall athlete population (1 in 5,200 vs. 1 in 53,703 athletes per year)."

While sudden cardiac death is rare, it is incredibly devastating and may be preventable with appropriate screening, although the appropriate screening has yet to be identified. A University of Wisconsin grouped published their protocol for the 5-minute screening echocardiogram for athletes, where they look at the following:

  • Parasternal long-axis

    • Aortic size, mitral & aortic valve appearance and doppler​, wall motion

  • Parasternal short-axis at the level of the aortic valve and the mid-left ventricle (LV)

    • Wall motion, wall thickness​

  • Apical 4-chamber

  • Apical 5-chamber view

    • Aortic valve, insufficiency​

  • Location of coronary arteries

  • Pulmonic valve with doppler

They screened 395 athletes and 84% were normal. The remaining athletes had mild abnormalities like trace/mild regurgitation. Five students had abnormalities that required a full echocardiogram and a clinic visit with a cardiologist before participation. These abnormalities included: two bicuspid aortic valves–one with moderate aortic insufficiency,the other with mild; one pulmonic stenosis; one thickened mitral valve with mild mitral regurgitation; and one mild cardiomyopathy.

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This protocol was successful at University of Wisconsin in screening a large number of athletes, 5 minutes at a time, and confirmed that none of its athletes had evidence of HOCM. Another interesting study from 2017 showed that medical students with minimal ultrasound training could effectively screen high school students for HOCM. They screened 2,332 high school athletes using the following criteria for abnormal left ventricle thickness using M-mode in parasternal short axis view:

  • Interventricular septum to left ventricular posterior wall ratio greater than 1.25 or

  • left ventricular thickness greater than 12 mm

People with abnormal studies underwent a repeat echocardiogram by the pediatric cardiologist. The medical students identified 137 athletes that met the HOCM screening criteria. Of those athletes, seven were confirmed to have HOCM. This criteria was 100% sensitive to pick up all the HOCM cases.

In Italy, annual screening of athletes has been taking place since 1979. Over a 17 year period, a New England Journal prospective study looked at sudden cardiac death in athletes vs non-athletes over 35 years old. Of 269 sudden deaths in young people, 49 occurred in competitive athletes (44 male and 5 female athletes; mean [±SD] age, 23±7 years). Based on autopsies of all the people who died, the most common causes of sudden death in athletes were somewhat different than in the U.S. They were:

  • arrhythmogenic right ventricular cardiomyopathy (22.4 percent)

  • coronary atherosclerosis (18.4 percent)

  • Anomalous origin of a coronary artery (12.2 percent)

  • Hypertrophic cardiomyopathy caused only 1 sudden death among the athletes (2.0 percent) but caused 16 sudden deaths in the nonathletes (7.3 percent), and was detected in 22 athletes (0.07 percent) at preparticipation screening.

POCUS Screening for all?

With a 5 minute focused echo exam, or an even more simplified LV thickness measurement via POCUS, it seems likely that point of care ultrasound could play an enormous role in quickly screening young athletes to discover potentially dangerous pathology prior to aggressive physical activity. 

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