One of the most common medical approaches to the treatment of coronary artery disease (CAD) is the percutaneous coronary intervention (PCI) which became frequent due to high efficiency and safety of this procedure. Modern-day advances in pharmacotherapy and the device innovations over the last thirty years enhanced the benign outcomes of patients with unstable or multivessel CAD, and multiple co-morbidities, treated by PCI .

In-stent restenosis (ISR) is a recognized complication following percutaneous coronary intervention in which the luminal diameter is narrowed through neointimal hyperplasia and vessel remodeling. Although rates of ISR have decreased in most recent years owing to newer generation drug-eluting stents, thinner struts, and better intravascular imaging modalities, ISR remains a prevalent dilemma that proves to be challenging to manage. Several factors have been proposed to contribute to ISR formation, including mechanical stent characteristics, technical factors during the coronary intervention, and biological aspects of drug-eluting stents .identification of risk factors and mechanisms underlying ISR is necessary for understanding the process, the risk stratification, and optimal treatment development. Restenosis, as a physiological response to mechanical damage, involves two mechanisms which are neointimal hyperplasia and vessel remodeling [3]. Several factors such as age, diabetes mellitus, hypertension, stenting of small coronary arteries, and final total length of stents have been shown to be associated with an elevated risk of restenosis.

Inclusion Criteria:

• patients with CAD

Exclusion Criteria:

• PATIENTS WITHOUT OTHER HEALTH PROBLEMS

This cross-sectional study will include all patients with stable CAD who had previously undergone balloon angioplasty with stenting using drug-eluting stents that referred to the catheterization lab unit of Sohag University for recurrence of angina symptoms or positive cardiac tests. According to the results of the control angiography, the patients will be divided into two groups: patients with ISR confirmed by coronary angiography (angiographic restenosis of more than 50% of the target vessel) and patients without restenosis non ISR group. The patients with ISR were classified into subgroups by the terms of the restenosis development ( early before 12 months & late after 12 months).