Heavily calcified and densely fibrotic coronary lesions continue to represent a challenge for percutaneous coronary intervention (PCI), as they are difficul to dilate and it is difficult to deliver and implant drug-eluting stents (DES) properly. Poor stent deployment is associated with high rates of periprocedural complications and suboptimal long-term clinical outcomes. Thanks to the introduction of several adjunctive PCI tools, like cutting and scoring balloons and to atherectomy devices, the treatment of such lesions has become increasingly feasible, predictable and safe. A step-wise progression of strategies is described for coronary plaque modification, from well-recognised techniques to techniques that should only be considered when standard manoeuvres have proven unsuccessful. We highlight these techniques in the setting of clinical examples how best to apply them through better patient and lesion selection, with the main objective of optimising DES delivery and implantation, and subsequent improved outcomes.

DES restenosis in the ULM artery can be managed in most cases with a minimally invasive approach, achieving favorable early and late results.

The residual SYNTAX score is a useful method to quantify incomplete revascularisation in patients undergoing PCI for 3VD. Complete revascularisation (rSYNTAX=0) is achieved in only a minority and, for them, the mortality rate is low.

Coronary sinus interventions (CSI) are a class of invasive techniques (surgical and percutaneous) originally proposed in the first half of the 20th century, aiming to treat ischaemic heart disease by acting on the venous coronary system. Three main classes of CSI have been proposed and tested: (1) retroperfusion technique, (2) retroinfusion technique and (3) coronary sinus occlusion techniques. They all share the principle that a controlled increased pressure within the coronary sinus may promote a retrograde perfusion of the ischaemic myocardium with consequent cardioprotection. Development of arterial treatments including coronary aortic bypass grafting and then percutaneous coronary intervention deflected interest from interventions on the coronary venous system. However, CSI may still have a possible niche role today in specific and selected clinical contexts in which existing therapies are insufficient. In this review paper, we aim to revise the rationale for CSI, describing the details and the evidence collected so far about these techniques and to provide insights about the main clinical scenarios in which these strategies may find a contemporary application in combination or as an alternative to existing approaches.