The goal of this observational retrospective and prospective multicentric trial is to learn about the impact of bail-out stenting (BOS) after drug coated balloon (DCB) percutaneous coronary angioplasty (PCI) in de novo coronary stenosis.The main question to answer is:

- if BOS PCI leads to an higher rate of 1-year target vessel failure that DCB-only PCI.

Participants will receive DCB PCI in de novo coronary stenosis. Treatments they'll be given should be:

• DCB-only PCI
• BOS PCI

Researchers will compare DCB-only and BOS group to see if addictive stent implantation for DCB-PCI complication is relate to an higher rate of target vessel failure.

Target vessel is the primary endpoint, defined as:

• cardiovascular death
• target vessel myocardial infarction
• clinical driven target vessel revascularization
• angiographic restenosis

Drug coated balloon (DCB) percutaneous coronary intervention (PCI) has been shown to be as effective as last generation drug eluting stent (DES) PCI in many randomized trials. However a not negligible rate of patients must receive a bail-out stenting (BOS) implantation after DCB-PCI. Only some studies report that the rate of MACE of these patients is higher than DCB-only or DES-PCI ones. Even if the BOS patients MACE rate is two times more than DCB-only or DES-only, due to the small amount of BOS patients in these studies there were not a statistically significant difference.

According to these evidence, BOSS study researchers will compare target vessel failure (TVF) rate in DCB-only and BOS group resulting from all vessel size de novo coronary artery stenosis DCB-PCI.

TVF as primary endpoint will include:

• cardiovascular death
• target vessel myocardial infarction (TV-MI). According to the third universal definition of myocardial infarction TV-MI will be considered a non fatal myocardial infarction with the evidence of myocardial necrosis in the vascular territory of previously treated target vessel
• clinical driven target vessel revascularization (CD-TVR). CD-TVR will be considered as any repeat intervention of any segment of the target vessel, defined as the entire major coronary vessel proximal and distal to the target lesion.
• Angiographic restenosis. It will considered in case of restenosis as either a > 50% loss of initial gain of the target lesion.

The trial will enroll all patients who received a de novo DCB-PCI from January 2020 to December 2023. The population will be divided into two groups:

• DCB-only PCI
• BOS PCI

Bail-out stenting will be done in case of high grade coronary dissection (> or equal to NHLBI grade C) or in case of > 30% recoil, according with International DCB Consensus.

Inclusion Criteria:

• De novo DCB PCI of at least one coronary artery
• Hybrid PCI of bifurcation (main branch stent and side branch DCB)
• Hybrid PCI of coronary artery with more than one stenosis (at least 10 mm of distance between edge of stent and DCB PCI segment)

Exclusion Criteria:

• in-stent restenosis
• more than 1 year life expectancy

All de novo DCB PCI ≥ 18 years-old patients who meet inclusion/exclusion criteria.