MRI Helps Screen Teens for SCD Risk at Exercise, but Should It?

Marlene Busko

March 31, 2017

WASHINGTON, DC — When more than 5000 middle-school children were screened with ECG and MRI for predisposition to sudden cardiac death during intense exercise, 1.48% had findings that suggested that they were in fact at high risk[1].

The most common findings putting them in the high-risk category were a corrected QT interval (QTc) above 470 ms on ECG, followed by an MRI-detected coronary anomaly.

MRI-detected dilated cardiomyopathy or hypertrophic cardiomyopathy (HCM) was rare.

With this type of screening program, cardiologists would be "called in to evaluate only 1.5% of all candidates, whereas the other 98.5% receive definitive reassurance" about their risk of sudden cardiac death, said Dr Paolo Angelini (Texas Heart Institute, Houston), presenting these findings from the Screen to Prevent (S2P) study at the American College of Cardiology (ACC) 2017 Scientific Sessions.

Paolo Angelini

"Our innovative MRI screening method can be potentially proposed for screening young candidates involved in sports and in military exercises," he suggested.

"Obviously, the elephant in the room is the cost," session panel member Dr Martin S Maron (Tufts Medical Center, Boston, MA) observed. Some of the cost of an MRI could be mitigated if the technique demonstrated the power to detect things that couldn't be detected with less expensive imaging, he added. "Were echos done here, in cases, for example, where structural heart disease was identified (such as dilated cardiomyopathy, HCM, or anomalous coronaries)? Were they picked up, or could they have been picked up with echo, clinical history, or ECG?" he asked.

Angelini replied that it cost $250 to screen each child with an ECG and MRI. "The number of screened patients needed to identify one case of probable high-risk [of sudden cardiac death] was 67 patients, which cost $16,750," he said. "In high-risk patients, especially in elite athletes, [MRI] is an important test to do."

"In the US we screen with history and physical, " Maron commented to heartwire from Medscape. "We don't even do ECG screening. This is going beyond. You're jumping way up the ladder here."

MRI is "a really expensive, powerful complicated test," he continued. "There's no question it gives you very beautiful pictures." But the question is, "could those heart diseases be detected by echo, which is cheaper, or even ECG?"

There is "no role right now for MRI for screening. You have to say that. There could be a role for MRI in the evaluation of athletes who have heart disease that's detected with other methods, but to go beyond that would be unrealistic," according to Maron.

Mass Screening Program in Children

Preexisting heart defects can predispose young athletes to die of sudden cardiac death during strenuous exertion. But if heart defects were detected earlier in a mass screening program and children knew that they had these defects, potentially some cases of sudden cardiac death might be averted, according to Angelini.

The Screen to Prevent (S2P) study was designed to see whether a program of screening young people using ECG and MRI was effective in detecting high-risk cardiovascular conditions.

The researchers screened 5255 schoolchildren who were 11 to 14 years old and attending middle school in Houston, TX. The schoolchildren had a mean age of 12.9, and 51% were male.

The participants filled in a medical questionnaire and had an ECG and an MRI in one session.

Of the 5255 children, 78 children had a high-risk cardiovascular condition detected by ECG and/or MRI.

Prevalence of High-Risk Cardiovascular Findings in 5255 Children

MRI/ECG findings Children, n (%)
ACAOSa 23 (0.44)
Dilated cardiomyopathya 12 (0.23)
Hypertrophic cardiomyopathya 3 (0.06)
Brugada patternb 1 (0.02)
WPW patternb 3 (0.06)
Prolonged QT interval (>470 ms)b 36 (0.69)
Total 78 (1.48)
ACAOS=anomalous origin of a coronary artery from the opposite sinus
a. Detected by MRI
b. Detected by ECG

Panel member Dr Richard J Kovacs (Indiana University, Indianapolis) wondered why the researchers chose to screen 13-year-olds. Angelini replied that the peak mortality in sudden cardiac death occurs at age 19, so they wanted to screen at a younger age.

The researchers hope to do a follow-up study at age 15 to 19 to see whether cardiomyopathy has progressed or if there are new cases, he added.

The study was funded by an unrestricted grant from a donor in Houston. Angelini has no relevant financial relationships.

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