Addition of Digoxin Improves Cardiac Function in Children With the Dilated Cardiomyopathy With Ataxia Syndrome: A Mitochondrial Cardiomyopathy

Abstract Background The dilated cardiomyopathy with ataxia syndrome (DCMA) is a rare mitochondrial disorder characterized by progressive cardiomyopathy, prolonged QT interval and early death in childhood related to intractable heart failure. We present a case series of 9 children with DCMA who demonstrated functional improvement and favourable left ventricular remodeling only after digoxin was added to their medical therapy. Methods A retrospective review of 46 patients with DCMA followed at the Alberta Children's Hospital from 2005 to 2017 identified 9 patients who were treated with digoxin and had serial echocardiography data. For each subject, we calculated the difference between baseline and follow-up for left ventricular ejection fraction (LVEF), end-diastolic dimension (LVEDD), and end-systolic dimension (LVESD) as determined by echocardiography. Results Patients were on average 45.6 ± 59 months of age when digoxin was started with a mean LVEF of 40% ± 11% when digoxin was started. Seven patients were on angiotensin-converting enzyme inhibitors (ACEIs) at the time of initiation of digoxin, and all were on β-receptor antagonists (BB). After being on digoxin for a mean of 11.7 ± 10.9 months, average LVEF improved to 55% ± 10% ( P  = 0.0005), and there were significant decreases in the Z-scores for LVEDD (+2.1 ± 1.9 to +0.65 ± 1.4, P  = 0.02) and LVESD (+3.83 ± 2.07 to +1.79 ± 1.76, P  = 0.01). Conclusions In children with DCMA, we report that digoxin seems to have additive beneficial properties when combined with ACEI and BB therapy. This novel observation may have implications for the medical treatment of mitochondrial cardiomyopathies.