Inclusion Criteria:  Willing and able to provide informed consent Male or female, ≥18 years of age at study entry Referred to an NHS Trust for stress echocardiography for investigation of ischaemic heart disease  Exclusion Criteria:  More than moderate valvular heart disease Left ventricular outflow tract obstruction defined as a gradient > 30mmHg (fixed or dynamic; supravalvular, valvular or sub-valvular) Significant co-morbidities (e.g. cancer) with an expected life-expectancy of under 12 months in the investigator's opinion Previous coronary artery bypass graft or other cardiac surgery Congenital or inherited myocardial disease