Researchers confirm the need for cardiac follow-up in patients with Friedreich ataxia, with particular focus on left ventricular ejection fraction (LVEF) as a predictor of worse prognosis.
They describe the evolution of two cardiac groups; a large low-risk group (78.6%) with normal LVEF at baseline that declined slightly but remained in the normal range and a smaller high-risk group (21.4%) with a low LVEF that progressively declined during an average of 10.5 years of follow-up.
“This finding demonstrates the importance of cardiac follow-up in [Friedreich ataxia] and the necessity for patient stratification in therapeutic trials”, they write in JAMA Neurology.
The team, led by Alexandra Durr (Hôpital de la Salpêtrière, Paris, France), studied 133 patients with genetically confirmed Friedreich ataxia and referred for cardiac evaluation.
The 10-year survival rate was 88.5% and among the 15 patients who died, 12 (80%) died due to cardiac causes, including progressive heart failure, atrial fibrillation and cardioembolic stroke.
Multivariate analysis showed that the strongest predictor of death was a longer length of GAA repeats on the shorter allele of the frataxin gene, which in turn causes a greater loss of frataxin, with a hazard ratio (HR) of 1.85 per additional 100 repeats. The other two factors significantly associated with death were a higher LV mass index, indicative of hypertrophy, at an HR of 1.19 with every 10 g/m3 increase and a smaller LVEF, at an HR of 0.42 with every 10% decrease.
The researchers note that LVEF deteriorated slightly over time, with significant alterations occurring in those at high cardiac risk. Its evolution was dependent on the length of the shorter GAA repeat allele and was independent of cardiac hypertrophy.
“As recommended, cardiac follow-up in [Friedreich ataxia] is necessary to identify early systolic LV dysfunction because clinical signs of cardiac dysfunction develop only later in the course of the disease”, the team comments.
They note that new echocardiography techniques, such as speckle tracking imaging, which can detect cardiac contractility before a decrease in LVEF, may be useful in monitoring patients with Friedreich ataxia.
The researchers also recommend the use of beta blockers, angiotensin-converting enzyme inhibitors or mineralocorticoid receptor antagonists in patients with LVEF below 50% to modify further expected cardiac complications.
Durr et al assessed the role of neurological impairment as well, using the Scale for the Assessment and Rating of Ataxia and the International Cooperative Ataxia Rating Scale, but found no association with cardiac change over time. Also, initiation of wheelchair use as an indicator of severity did not differ between the high and low cardiac risk groups.
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