Atrioventricular Block Common In Children With Multisystem Inflammatory Syndrome

Atrioventricular block (AVB) occurs in about one of five children with multisystem inflammatory syndrome (MIS-C) following SARS-CoV-2 infection, according to a new study.

Initial reports from Europe on the features of MIS-C included cardiovascular complications in a high proportion of patients.

Dr. Audrey Dionne and colleagues from Boston Children's Hospital characterized the incidence of echocardiographic and electrocardiogram (ECG) changes in a retrospective study of 25 children and young adults who were admitted with a diagnosis of MIS-C from March through May.

Ten of these patients (40%) had previous significant morbidities, including asthma (three patients), obesity (three patients), a previous episode of Kawasaki disease (two patients), and sickle-cell anemia, mitochondrial disease and triploidy with prematurity and chronic respiratory failure posttracheostomy (one patient each).

Echocardiographic assessment demonstrated left ventricular systolic dysfunction in 15 patients (60%) a median five days after fever onset. Function normalized in 13 of these 15 patients a median five days after onset, but mild ventricular dysfunction persisted in the other two patients.

Five patients developed new coronary-artery enlargement a median five days after fever onset: Three had coronary artery dilation and two had small coronary-artery aneurysms.

On ECG, first-degree AVB was evident in five patients (20%) a median six days after fever onset. AVB progressed to second- or third-degree in four of these patients within three days after onset of first-degree AVB, the authors report in Pediatrics.

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Second- and third-degree AVB resolved in all patients within one to six days, and first-degree AVB resolved in four of five patients between 10 and 14 days after fever onset. One patient still had first-degree AVB 75 days after fever onset.

All five patients with AVB had ventricular dysfunction on the echocardiogram, and four of five required inotropic support for hypertension or shock at the time of initial presentation. None of the patients, though, required acute resuscitation, pacing, or medication to improve AV conduction or increase the escape rate.

None of the patients with AVB had elevated troponin levels, but all patients with second- or third-degree AVB had elevated brain natriuretic peptide (BNP) levels.

Other ECG changes included prolongation of the corrected QT interval and nonspecific ST-segment changes, both of which were more common in patients with AVB than in those without AVB.

"This experience highlights the importance of ECG monitoring throughout admission to identify patients with PR prolongation at risk for progression to high-grade AVB," the authors conclude. "Large multicenter studies are required to better understand the pathophysiology, clinical presentation, and impact of treatment on atrioventricular conduction disease in MIS-C."

Dr. Paraskevi Theocharis of Evelina London Children's Hospital, who recently reported that pancarditis with cardiac dysfunction and myocardial edema are common in children with MIS-C, told Reuters Health by email, "The results of this study didn't surprise me, as we have observed similar findings in our cohort. However, it would be interesting to follow up these patients in series with repeated ECGs to see the natural course of the disease."

"I believe that the ECG changes observed are secondary to the myocarditis-myocardial edema," he said. "Therefore, with the correct management (these) will resolve as we expect the edema to resolve."

"We still need to conduct bigger studies in larger cohorts of patients to see the natural course of the disease," Dr. Theocharis added. "Multidisciplinary team management is crucial, (as is) continuous monitoring."

Dr. Dionne did not respond to a request for comments.

—Will Boggs MD

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