Normal left ventricular ejection fraction and mass but subclinical myocardial dysfunction in patients with Friedreich's ataxia

Myocardial involvement in Friedreich's ataxia (FRDA) is characterized by iron deposits, diffuse fibrosis, and focal necrosis. We hypothesized that subclinical left ventricular (LV) dysfunction may occur in 'FRDA patients who have normal LV ejection fraction (LVEF) and mass.

Twenty patients homozygous for the GAA expansion in the frataxin gene (mean age: 35 ± 16 years) and twenty age- and sex-matched controls (mean age: 34 ± 15 years) were studied using conventional echocardiography and speckle-tracking imaging. The two groups did not differ in terms of the LVEF (68 ± 6 vs. 67 ± 6%, in patients and controls, respectively) or LV mass (91 ± 20 vs. 82 ± 17 g/m²). Global systolic longitudinal (−15.3 ± 2.1 vs. −17.5 ± 1.6%, P = 0.001) and circumferential (−19.5 ± 2.9 vs. −21.4 ± 2.6%, P = 0.034) strain, and peak LV twist (9.2 ± 3.3 vs. 11.7 ± 2.3°, P = 0.008) were significantly reduced in patients compared with controls. Indexed stroke volume was also significantly lower in patients (36 ± 5 vs. 43 ± 8 mL/m², P = 0.0012) and this decreased LV pump performance was associated with a concentric remodelling pattern (relative wall thickness: 0.47 ± 0.08 vs. 0.35 ± 0.05, P < 0.001).

There is evidence of morphological and functional abnormalities in FRDA patients with normal LVEF and mass.