The usual arterial access route is via the radial or femoral artery. The diagnostic angiography report comments on each main epicardial artery in turn, starting with the left system. The left main stem (LMS) bifurcates into the left anterior descending artery (LAD) and left circumflex (LCx). Then the right coronary artery (RCA) is described (for common abbreviations see Box 1). On occasions branch vessels will also be described as a subset of their main epicardial vessel. The angiogram report may refer to either the LCx or the RCA as the ‘dominant’ vessel/territory, to indicate which of the two vessels gives rise to the posterior descending artery (PDA) branch. In approximately 70% of subjects the PDA will arise from the RCA. For a diagram of the coronary circulation, see Figure 1.
Box 1. Summary of commonly used abbreviations.
BMS = bare metal stent. CTO = chronic total occlusion. DAPT = dual-antiplatelet therapy. DEB = drug-eluting balloon. DES = drug-eluding stent. FFR = fractional flow reserve. IABP = intra-aortic balloon pump. IVUS = intravascular ultrasound. NSTEMI = non-ST-elevation myocardial infarction. OCT = optical coherence tomography. STEMI = ST-elevation myocardial infarction.
A number of different techniques may be used to assess ischaemia (functional assessment). The most commonly used technique is fractional flow reserve (FFR), commonly known as a pressure-wire study. In this investigation, a wire or catheter with a pressure sensor measures the pressure drop across a coronary lesion at maximal hyperaemia, that is, the coronary artery at its maximal size, typically achieved with an infusion of adenosine. If the FFR is ≥0.80, percutaneous coronary intervention (PCI) is not undertaken, because performing angioplasty in this situation would not benefit the patient.1,2
iFR (instant free-wave ratio) is an alternative to FFR that does not require maximal hyperaemia.3
Intra-coronary imaging tools include intravascular ultrasound (IVUS) and optical coherence tomography (OCT). Both offer the cardiologist the ability to directly image the coronary artery lumen. This can give information on the size and length of stent required, and the type of coronary artery lesion and the current state of any previously deployed stents.