A 32-year-old female patient presented with cardiac failure because of systolic dysfunction. Five years before, a DDD pacemaker had been implanted because of complete atrioventricular block. Echocardiographic examination disclosed left ventricular hypertrabeculation/non-compaction. Because of sinus tachycardia, ivabradine was started and the patient’s left ventricular function returned to normal within 4 months. Recurrent creatine-kinase elevation and reduced nicotinamide adenine dinucleotide staining on muscle biopsy suggested metabolic myopathy.