Manganese-Enhanced Magnetic Resonance Imaging of the Myocardium

Inclusion Criteria: All subjects to be entered must: * ≥ 18 years of age * if female, be non-pregnant as evidenced by a urine pregnancy test or post-menopausal or surgically sterile * provide written informed consent after having received oral and written information about the study Additionally, cohort-specific inclusion criteria as follows: Healthy Volunteers • Healthy adult with no known pre-existing medical conditions Ischaemic Cardiomyopathy * Ischaemic cardiomyopathy as diagnosed by reduced LV ejection fraction (≤40%) secondary to one or more ischaemic events * Angiographically demonstrated LMS, LAD disease, or ≥2 vessel disease * NHYA class I-III heart failure, with stable symptoms not requiring change to diuretic therapy in the preceding month Dilated Cardiomyopathy * Dilated cardiomyopathy characterised with echocardiography by reduced left ventricular systolic function with impaired systolic function (ejection fraction \<40%). * NHYA class I-III heart failure, with stable symptoms not requiring change to diuretic therapy in the preceding month Hypertrophic Cardiomyopathy * Established diagnosis of hypertrophic cardiomyopathy * Left ventricular wall thickness ≥15mm in any segment * Repolarisation abnormalities on 12-lead electrocardiogram NHYA class I-III heart failure, with stable symptoms not requiring change to diuretic therapy in the preceding month Exclusion Criteria: * have a positive pregnancy test * women who are breast feeding * received an investigational drug or device within 30 days prior to administration of Mangafodipir * have known hypersensitivity to ondansetron or other selective serotonin 5-HT3 receptor blockers * have a history of ongoing drug abuse or alcoholism * have a history of torsades or prolonged QT/QTc interval * atrioventricular block (1st, 2nd or 3rd degree) * atrial fibrillation or flutter * have NYHA Grade IV heart failure * have abnormal liver function tests or a history of liver disease * have a baseline eGFR (estimated glomerular filtration rate) of \<30 mL/min) * have uncontrolled hypertension * have any contraindications to MRI, including implanted devices/pacemakers * be maintained on either a calcium channel blocker or digoxin * known diagnosis of phaeochromocytoma Additionally, cohort-specific exclusion criteria as follows: Hypertrophic Cardiomyopathy * Coronary artery stenosis \>50% any vessel * Previous myocardial infarction * Previous alcohol septal ablation * Moderate or severe aortic stenosis (mean gradient \>25 mmHg, mean AVA ≤1.5 cm2 or peak velocity ≥3 m/sec),