Is left ventricular longitudinal strain a good prognostic factor in Friedreich ataxia?

Abstract

Friedreich ataxia (FRDA) is a rare genetic ataxia. The causal mutation is an expanded trinucleotide repeat (GAA) in the frataxin gene. Hypertrophic cardiomyopathy in FRDA is the major cause of early death. Patients with progressive decline of the left ventricular ejection fraction (LVEF) have the worst prognosis. The aim of the study was to evaluate the prognostic value of 2D global longitudinal strain (GLS) compared to LVEF in FRDA patients. From 2003 to 2017 consecutive patients with genetically confirmed FRDA were included. GLS was retrospectively performed. News was obtained for all patients until April 2018. The study included 156 patients of 35 ± 12 years (mean ± SD) with an age at disease onset of 17 ± 11 y and GAA repeat on the shorter allele of 590 ± 241 pb. The following echocardiographic parameters were studied: LVEF 64 ± 9%, GLS -19.8 ± 5% ( n = 141), septal wall thickness (SWT) 11.4 ± 2.5 mm, posterior wall thickness (PWT) 10.4 ± 1.8 mm, LV end diastolic diameter (LVEDD) 44.4 ± 6 mm. Correlation between GLS and LVEF was 0.31 ( P = 0.0002). After a mean follow-up of 7.7 ± 4.0 y, 17 (11%) patients died and the outcome (cardiac arrhythmia, heart failure, stroke or death) concerned 28 (18%) patients. In univariate analysis (Cox model), factors associated with mortality were: GLS (HR:1.2;95%CI 1.10–1.32, P = 0.0001), LVEF (HR:0.88;95%CI 0.85–0.92, P < 0.0001), GAA (HR:1.28;95%CI 1.11–1.47, P = 0.0008), age at onset (HR:0.84;95%CI 0.76–0.94, P = 0.002), LVMi (HR:1.02;95%CI 1.01–1.04, P = 0.0078), SWT (HR:1.18%CI 1.01–1.36, P = 0.03) and LVEDD (HR:1.09;95%CI 1.00–1.19, P = 0.04). In multivariate analysis LVEF was the only independent predictor of long-term mortality (HR:0.93;95%CI 0.88;099, P = 0.02). GLS was also an independent predictor of the composite outcome in multivariate analysis. GLS is a predictor of morbimortality but is not superior to LVEF in FRDA patients.