Patients

The eligibility criteria are summarised in box 1. Briefly, patients are 18–75 years of age, with a diagnosis of HCM in keeping with the European Society of Cardiology HCM guidelines, that is, ‘a wall thickness≥15 mm in one or more LV myocardial segments that is not explained solely by loading conditions’,¹ and NYHA class I, II or III. Key exclusion criteria include previous or planned septal reduction therapy, uncontrolled hypertension, known LV ejection fraction of <50%, previously documented persistent atrial fibrillation, previously documented other cardiomyopathic cause of myocardial hypertrophy (eg, amyloidosis, Fabry disease or mitochondrial disease), anaemia, iron deficiency, copper deficiency, pacemaker or implantable cardioverter–defibrillator and contraindication to MRI scanning.

(It is recognised that in the ESC guidelines, a clinical diagnosis of HCM in first-degree relatives requires a wall thickness that is less than this value; however, ≥15 mm is applied here in order to ensure that all participants have an unequivocal phenotype).

*The original upper age limit was 70 years, but this was increased to 75 years in a protocol amendment in order to aid recruitment. See online supplemental table 1 for further details.

CMR, cardiovascular magnetic resonance; EF, ejection fraction; ESC, European Society of Cardiology; HCM, hypertrophic cardiomyopathy; LV, left ventricular; NYHA, New York Heart Association; TEMPEST, The Efficacy and Mechanism of Trientine in Patients with Hypertrophic Cardiomyopathy.