Boston Children’s criteria IDs kids at risk for arrhythmias during stress tests

Clinically significant arrhythmias are rare during exercise stress tests (ESTs) in pediatric heart patients, researchers reported in JACC: Clinical Electrophysiology this week, but those most at risk for life-threatening events can be identified from a set of predefined risk factors like cardiomyopathy and ventricular dysfunction.

Stress tests are an integral part of pediatric heart centers, wrote Oliver M. Barry, MD, and colleagues at Boston Children’s Hospital. They’re used to evaluate functional capacity in young CVD patients and mitigate the risk of exercise-induced arrhythmias after hospitalization, but research hasn’t focused on ESTs in high-risk children. 

“Safety data regarding ESTs in children and young adults with congenital heart disease (CHD) are limited and largely extrapolated from adults with acquired cardiovascular disease,” Barry and co-authors wrote. “Previous pediatric studies have been limited by small testing volume and a trend toward milder disease severity. 

“Due in part to the paucity of data in high-risk populations, there is considerable institutional variability in the willingness to undertake ESTs in some patient populations.”

At Boston Children’s, ESTs are performed regularly but are directly supervised just 10 percent of the time, the authors said. A pre-developed set of a priori high-risk criteria, including CHD, cardiomyopathy, having an implantable cardioverter-defibrillator (ICD), severe ventricular dysfunction, complex arrhythmia history, coronary disease with concern for ischemia and pulmonary hypertension, were developed to identify patients at an elevated risk for arrhythmias during a stress test. 

To test the efficacy of those criteria, Barry and his team studied data from 5,307 ESTs performed at Boston Children’s Hospital between 2013 and 2015. Of the subjects, who were on average around 16 years old, 20 percent presented with complex CHD.

After evaluation, the researchers found at least one high-risk criterion was present in 10 percent of tests. ICD and cardiomyopathy were the two strongest indicators of high risk, reaching 37 percent and 36 percent prevalence, respectively.

Nearly half of all ESTs resulted in some degree of arrhythmia, but just 33 patients—0.6 percent of the pool—required test termination. Three events required cardiopulmonary resuscitation, all with high-risk criteria. 

“The overall incidence of serious arrhythmia events with ESTs in a cohort with pediatric and CHD patients was low,” Barry et al. wrote. “Using pre-defined a priori high-risk criteria, we effectively identified all of the patients who subsequently had the most serious adverse events.”

The risks associated with ESTs seemed to be most severe in patients with clinically apparent hypertrophic cardiomyopathy, they said. Absence of a high-risk criterion was linked to a 99.7 percent negative predictive value for an arrhythmia that required test termination and a 99.96 percent negative predictive value for something more serious.

“These data, combined with the overall low risk of ESTs, permitted informed choices regarding referral for and supervision of ESTs and limited direct supervision to 10 percent or less of the test volume,” the researchers said. “Although a small number of patients will having life-threatening arrhythmias during ESTs, with appropriate supervision and resources, these arrhythmias can usually be managed effectively.”