Introduction

Refractory angina (RA) is conventionally defined as a chronic condition (≥3 months in duration) characterised by angina caused by coronary insufficiency in the setting of coronary artery disease (CAD) which cannot be controlled by a combination of medical therapy, angioplasty or bypass surgery and where the presence of reversible myocardial ischaemia has been clinically established to be the cause of the symptoms.1

Precise estimates of the prevalence and incidence of RA are not available. Several sources suggest that this is a large and growing problem. Much of the difficulty arises around the definition and heterogeneity of patients labelled with a diagnosis of RA. Data from the Canadian Community Health Survey (2000–2001) suggest that approximately 500 000 Canadians are living with unresolved angina.2 The proportion of these patients living with true RA is not known.3 It is estimated that between 600 000 and 1.8 million patients in the USA have RA, with as many as 75 000 new cases diagnosed each year.4 In Europe, the annual incidence of RA is estimated at approximately 30–50 000 new cases per year.1 No specific figures exist for the UK. However, if one applies the findings of Williams et al 5 who noted that 6.7% of patients undergoing angiography in a contemporary series had no revascularisation option, to the 247 363 angiograms performed in England in 2014,6 one …