Target Vessel Failure After Laser Assisted Percutaneous Angioplasty Versus Balloon-based Treatment for Drug Eluting In-stent Restenosis

Stent restenosis (ISR) is an increasingly common problem; in fact, approximately 10% of coronary angioplasty procedures involve the treatment of a previously implanted stent. ISR is defined as a 70% narrowing of the visually estimated coronary lumen within 5 mm of the proximal and distal portions of a previously implanted stent or, alternatively, a 50% narrowing associated with evidence of functional significance (e.g., ischemic symptoms or abnormal flow reserve). Treatment of ISR in bare-metal stents (BMS) has been shown to be safe and effective using both drug-eluting stents (DES) and drug-coated balloons (DCB). However, in the case of DES ISR, the rate of further restenosis is still high (approximately 13% at one year). The treatment of stent restenosis consists of the use of balloon-based methods, i.e., coronary balloons of various types, which may include the use of semi-compliant, non-compliant, scoring balloons, cutting balloons, with subsequent implantation of a new coronary stent or the elution of an antiproliferative drug with DCB. Some small observational monocentric studies suggest the efficacy of Excimer Laser Coronary Atherectomy (ELCA) in this context, allowing for a wider coronary lumen, a better minimum stent area (MSA), and a numerically lower incidence of new stent restenosis. One of the biases of these studies, in addition to the small sample size, is the type of contrast used to perform ELCA treatment. In fact, in a significant number of patients, saline solution was used, which is known to reduce the effectiveness of this therapy.

Recent registry studies show a one-year restenosis recurrence rate of approximately 5% in patients treated for ISR with ELCA without the use of saline solution. However, these studies are insufficient to clearly define whether ELCA can be considered the treatment of choice in this context, as they are too small to evaluate the effect on clinical outcomes or do not have a control group treated with traditional techniques. The ability of ELCA treatment to remove intrastent neo-atherosclerotic tissue and resolve the under-expansion of previously implanted coronary stents are the reasons why better results than conventional techniques are expected in DES ISR angioplasty. In fact, these two components are considered among the main causes of new restenosis. Therefore, an ad hoc study with adequate statistical power may be able to demonstrate a significant reduction in target vessel failure (TVR), i.e., an event related to the treatment of the vessel site of stent restenosis, one year later in patients with DES ISR thanks to ELCA treatment compared to balloon-based therapy.

Demonstrating that Excimer Laser Coronary Atherectomy (ELCA)-assisted angioplasty treatment for DES ISR is associated with a lower incidence of Target Vessel Failure at 1 year compared to balloon-based angioplasty techniques may allow for better treatment of this type of patient.

• Degree of stent expansion [Time frame: During the procedure]