Irregular Heartbeat More Likely in FA Children With Enlarged Hearts

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by Steve Bryson, PhD |

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Children and adolescents with Friedreich’s ataxia (FA) who have an enlarged heart were found to have a high prevalence of irregular heartbeats, and were more likely to have early progression to end-stage disease, according to a nationwide U.K. study.

The age of onset and the characteristics of heart enlargement — called hypertrophic cardiomyopathy, or HCM — were varied, and overall mortality was similar to that of children with HCM due to other causes. Also, no children died suddenly over the course of the study.

But new data highlight that routine heart screening should be performed for all FA children, the researchers said.

“Although FA is a multisystemic disease, cardiovascular involvement is an important contributor to long-term outcomes, and the most common causes of death reported in postmortem studies are heart failure and arrhythmic events,” the team wrote, adding that “the cardiac prognosis for this population is not benign in childhood and adolescence.”

The study, “Friedreich’s ataxia-associated childhood hypertrophic cardiomyopathy: a national cohort study,” was published in the journal Archives of Diseases in Childhood.

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FA is a progressive disorder that primarily affects the nerves and muscles. One early symptom is walking difficulties due to a loss of coordination of the leg muscles.

Hypertrophic cardiomyopathy, called HCM for short — when the muscles of the heart become enlarged — occurs in up to 85% of people with FA. Although HCM frequently appears many years after the FA diagnosis, it can present in some pediatric patients.

However, the clinic characteristics of FA children and adolescents with HCM are poorly described in the literature, and knowledge of how the disease progresses is limited.

To learn more, investigators at the Great Ormond Street Hospital for Children NHS Foundation Trust, in the U.K., conducted “the largest childhood series to date” with researchers from throughout the country. Their study sought to characterize FA patients younger than 18 with HCM diagnosed over four decades.

The team identified 78 patients with FA-associated HCM, of whom 42 were male (53.9%). The mean age at FA diagnosis was nearly 10 years old, and at HCM diagnosis slightly under age 11.

HCM was diagnosed in 34 individuals (43.6%) before the age of 10; four (5.1%) were diagnosed with HCM before FA following the appearance of cardiac symptoms.

At the first heart assessment (baseline), 74 individuals (94.9%) met the diagnostic criteria for HCM, while 48 (66.7%) showed no symptoms. Among those with symptoms, 11 (39.3%) had chest pain, six (21.4%) experienced palpitations, and six (21.4%) had fainting (presyncope or syncope).

Nearly 40% of patients (11) experienced symptoms of heart failure.

A total of 12 patients (16.4%) started treatment with cardiac medications, and 12 (16.4%) received antioxidants.

Echocardiogram (ECG) tests were available for 41 patients, with all but two showing ECG abnormalities.

An atypical presentation was seen in two patients under the age of 5, both of whom had dilated hypokinetic cardiomyopathy. In this condition, the heart is enlarged with an impaired ability to pump blood.

The first child underwent a heart transplant, but was diagnosed with FA three years later after developing ataxia.

The second showed symptoms of heart failure and an enlarged heart, but — although listed for transplant — the child’s heart function recovered with medication. FA was diagnosed five years later.

The median follow-up during the study was 5.1 years, with 19 patients (24.4%) transitioning to adult care. At the last clinical visit, 33 of 76 patients assessed — 54.5% — were symptomatic. In all, 40 patients (56.3%) were prescribed cardiac therapies, and 23 (32.4%) were taking antioxidants.

The mean thickness of the left ventricle, characteristic of HCM, was not different compared with baseline assessments.

Five patients were found at baseline to have left ventricular systolic impairment — when the heart has difficulty pumping blood through the body. At follow-up, three showed normalization, one mild impairment, and one worsening. The child whose condition worsened required a heart transplant at age 4.

The researchers also sought to determine the impact of irregular heartbeat, or arrhythmia, on patient outcomes. ECG recordings were available for 51 patients (70.8%), of whom 39 had no detected arrhythmias.

Eight patients with irregular heartbeats, at a median age of 16.3, had atrial arrhythmias — those beginning in the upper chambers of the heart. Two of the eight developed heart failure and died. No differences in baseline characteristics were seen between patients with and without atrial arrhythmias, and no demographic or baseline clinical assessment predicted survival without atrial arrhythmias.

“A major novel finding in this study is the high prevalence of atrial arrhythmias in childhood FA-HCM, which were detected from adolescence onwards,” the researchers wrote.

At the last clinical review, 70 patients (89.7%) were alive. Among those who died, the cause of death was atrial arrhythmia-related in two cases; one was due to heart failure. Two of the deaths were from non-cardiac reasons and three were of unknown causes.

The overall mortality or cardiac transplant rate was 1.72 per 100 patient-years. That measure takes into account the number of patients and the overall follow-up time for each patient.

After five years, 96.5% were alive or did not undergo a heart transplant. That number was 80.8% after 10 years. There were no baseline or clinical characteristics that predicted transplant-free survival.

“This national study is the largest multicentre description of FA-associated HCM during childhood and describes a symptomatic [group] with variable age of progression and cardiac phenotype [characteristics],” the researchers wrote. “There was a high prevalence of atrial arrhythmias, most commonly in those with impaired [left ventricle] systolic function, and early progression to end-stage disease.”

“Overall mortality is similar to that reported in non-[FA] childhood HCM, but no patients died suddenly,” they added.

The researchers said their findings uncovered important new information about the long-term impact, on children with Friedreich’s ataxia, of having an enlarged heart due to the disease.

Moreover, the data support the practice of full pediatric screening for all FA patients, the team said, noting that “two-thirds were asymptomatic when first seen.”

“Routine, serial cardiac screening should be performed for all children with a diagnosis of FA,” they concluded.