Double blind, randomised, placebo-controlled trial of MitoQ (mitoquinol mesylate) in 106 patients with dilated cardiomyopathy, examining the effect of reducing mitochondrial oxidative stress on myocardial energetics and myocardial function using 31-phosphorus magnetic resonance spectroscopy and cardiovascular magnetic resonance.

Inclusion criteria

1. idiopathic or familial DCM
2. LVEF ≤45% on 2 imaging studies of any modality ≥3 months apart (may include CMR scan at baseline visit)
3. on guideline therapy for ≥3 months as determined by usual clinicians
4. sinus rhythm on 12-lead electrocardiogram
5. plasma NT-pro-BNP >250ng/L for those >65 years and >100ng/L for those aged ≤65 years within the last 6 months (may include sample at baseline visit)

Exclusion criteria

1. current persistent atrial fibrillation
2. contraindication to CMR
3. estimated glomerular filtration rate (eGFR) <30mls/min
4. current or planned pregnancy or current breast-feeding
5. clear environmental trigger such as excess alcohol intake, cardiotoxic chemotherapy or peripartum presentation
6. fibrosis burden >25% on CMR
7. current cancer (other than non-melanoma skin cancers)
8. current use of CoQ10
9. current participation in another randomised controlled trial