The aim of this study is to prospectively investigate the relationship of circulating endothelial progenitor cells at time of percutaneous coronary intervention to the subsequent development of in-stent restenosis or progression of coronary atherosclerosis.

Research on stem cells has identified a population of bone marrow-derived cells, called circulating endothelial progenitor cells (EPCs), that incorporate into sites of neovascularization and are home to sites of endothelial denudation thus contributing to the maintenance of vascular homeostasis.

Although extensive work has been conducted to verify if EPCs impairment plays a key role in coronary atherogenesis, it is still matter of debate if the extension and severity of coronary artery disease are associated with reduced or increased numbers of EPCs, as it remains unclear if these cells exert favorable or unfavorable effects at sites of percutaneous coronary intervention (PCI). One should consider, however, that most previous investigations have been hampered by discordant definitions of EPCs and by different timing of EPCs sampling, thus determining much uncertainty on the role of EPCs in restenosis and atherosclerosis progression. Furthermore, development of de novo lesions and post-PCI restenosis, which are pathophysiologically dissimilar, have not been examined concomitantly and serially over time.

Accordingly, the aim of this study is to carry out the first prospective assessment of the significance of subpopulations of circulating EPCs in the subsequent occurrence of restenosis or progression of coronary atherosclerosis after PCI. To this end, a pool of EPCs subtypes that are suggested to play some role in atherosclerosis is measured in a homogenous population of candidates to PCI. At variance with previous work, counts of EPCs are obtained in baseline conditions before PCI in order to avoid the confounding effect that the procedure exerts on EPCs.

Inclusion Criteria:

• evidence of complete revascularization of clinically important stenoses by PCI
• willing to undergo 8-month control angiography.

Exclusion Criteria:

• in-hospital death after PCI
• myocardial infarction during follow-up to exclude potential subacute stent
• unstable angina
• any increase in creatine kinase-myocardial band, troponin I, myoglobin, or liver enzymes above upper normal limit before PCI
• left ventricular ejection fraction<30%
• renal failure with creatinine>2 mg/dl
• treatment with statins at referral

consecutive patient sampling