The Longitudinal Course of Cardiomyopathy in Friedreich's Ataxia During Childhood

Background Clinical heart disease was recognized in the first descriptions of Friedreich's ataxia (FA). Cardiac manifestations reported for this progressive neurologic disease include hypertrophic cardiomyopathy, dilated cardiomyopathy, and electrophysiologic disturbances. Longitudinal data for childhood cases are limited. This study aimed to define the longitudinal course of the cardiac abnormalities with FA diagnosed during childhood and to correlate the presence of cardiomyopathy with clinical and genetic factors. Methods A retrospective chart review was conducted, with prospective, blinded interpretation of echocardiograms and electrocardiograms. All the patients with a diagnosis of FA referred to the cardiology department of a single institution from 1974 to 2004 were included in the study. Results This study investigated a total of 113 echocardiograms for 28 patients. Overall, the group had left ventricular hypertrophy and normal systolic function, with a median mass z-score of 2.48 (range, -3.8 to 35.6) and a median ejection fraction (EF) of 61% (range, 23-81%). Of the 28 patients, 23 (82%) had two or more echocardiograms. The median follow-up time to the most recent echocardiogram was 5.1 years (range, 0.4-16.5 years). Many in this longitudinal follow-up cohort (57%) showed hypertrophic cardiomyopathy on at least one echocardiogram, with the last follow-up assessment showing systolic dysfunction for 38% of these patients. There was a slow nonlinear decline in systolic function over time, with the mean EF decreasing more rapidly as age increased (p = 0.02) and maintenance of EF in the normal range until the age of 22 years. Of the 12 patients with systolic dysfunction and follow-up echocardiograms, 10 showed improvement to the normal EF range on at least one echocardiogram, and 5 remained normal through the last study. None of the trends in cardiac function and morphology correlated with frataxin GAA repeat length (the primary genetic defect in FA) or ambulatory status. One patient required an implantable defibrillator. There were no deaths or heart transplantations. Conclusions Overall, patients with FA have preserved cardiac function with increased mass throughout childhood. Because many patients who experience depressed systolic function show improvement in subsequent studies, evaluation for potentially reversible causes of heart failure should be conducted. Relative clinical stability during childhood and maintenance of normal systolic function into the second decade may be helpful for parent and patient education.