Cardiomyopathy in Friedreich's ataxia: assessment by echocardiography and cardiac magnetic resonance imaging

Cardiomyopathy is an important and frequently life limiting manifestation of Friedreich's ataxia (FA), the most prevalent form of autosomal recessive ataxia. FA associated cardiomyopathy is supposed to be of hypertrophic type. Recent therapeutical trials in FA aimed to reduce left ventricular mass by supplementation of the quinone coenzyme Q10 or its short-chain analogue idebenone with variable effects. To characterize FA associated cardiomyopathy and analyse cardiac parameters as potential outcome measures for therapeutical trials, we investigated 41 adult patients with genetically confirmed FA clinically, by electrocardiography, echocardiography and cardiac MRI. Cardiac signs and symptoms were present in 29% of patients with intermittent tachycardia and palpitations as the most frequent complaints. ECG revealed abnormalities, mostly repolarisation abnormalities, in 89% and increased Sokolow-Lyon index in 7% of patients. Interventricular septum was thickened in 32% of patients in echocardiography and 37% on MRI. Left ventricular hypertrophy was found in 6% of patients when assessed by echocardiography and in 29% with MRI. Interventricular septum thickness and left ventricular mass were not determined by age, duration of symptoms, severity of the disease or GAA repeat length. Longitudinal analysis of cardiomyopathy using echocardiography revealed substantial spontaneous increase as well as reduction in left ventricular mass during a 3 year follow-up.

We conclude that hypertrophic cardiomyopathy is present only in a minority of FA patients. Our data question left ventricular hypertrophy as primary outcome measure for forthcoming pharmacological interventions in FA and recommend cardiac MRI as the most accurate assessment of left ventricular anatomy in vivo with an interoberserver variability of less than 5%.