Phosphorus-31 two-dimensional chemical shift imaging in the myocardium of patients with late onset of Friedreich ataxia

Purpose: Friedreich ataxia (FRDA) is characterized by GAA expansions in the intron 1 of the frataxin gene correlating with disease onset and progression as well as cardiac affection. Accordingly, FRDA patients with early disease onset show a clear impairment of mitochondrial function in the myocardium. The purpose of this study was to investigate cardiac function and high-energy phosphate metabolism in FRDA patients with late disease onset. Procedures: Using a 1.5 T magnetic resonance scanner, cardiac phosphorus-31 two-dimensional chemical shift imaging was performed in ten patients (seven male, three female) with a late onset of FRDA and in 35 healthy, male controls. Ejection faction (EF) and interventricular septum thickness (IST) were determined by echocardiography. Results: The differences in left ventricular phosphocreatine (PCr) to beta-adenosine triphosphate (beta-ATP) ratios between both groups were not significant. FRDA patients had increased ISTs (10.8 +/- 1.6 vs. 9.7 +/- 0.9 mm; p=0.048), which correlated significantly with the left ventricular PCr to beta-ATP ratios (r=-0.644; p=0.04), and decreased EFs (52.24 +/- 7.72% vs. 64.09 +/- 4.25%; p=0.001) compared to normal controls. Conclusions: In contrast to FRDA patients with early disease onset, our patients collective exhibited a normal, probably compensated cardiac mitochondrial function, whereby IST and EF were mildly altered.