Chronic refractory angina pectoris: recent progress and remaining challenges

Refractory angina, also described as chronic refractory angina pectoris (CRAP), classically occurs in patients with advanced, often diffuse coronary artery disease (CAD) that failed to be completely revascularized by percutaneous coronary intervention (PCI) and/or coronary artery bypass graft (CABG) with remaining angina pectoris symptoms despite maximized pharmacological intervention. In the majority of patients with CRAP, myocardial ischaemia can be detected by perfusion imaging using either cardiac magnetic resonance imaging (CMR), stress echocardiography, myocardial scintigraphy, or positron emission tomography (PET). Chronic refractory angina pectoris has been a field of intense research and innovation during the past three decades. A number of novel modalities have been explored and introduced accordingly (Figure 1), in addition to significant improvement of PCI based on the introduction of novel technical equipment and skills. Promoted from the early 1990s on, one of the first concepts for reducing chronic ischaemia and for symptomatic improvement of CRAP patients has been therapeutic angiogenesis and therapeutic arteriogenesis using local delivery of growth factor therapy, as either protein or as gene therapy. The study by Hartikainen et al. in the present issue of the journal is the latest contribution of its kind and will be commented on in detail below.