ABSTRACT
Backgroud:chronic total coronary occlusions (CTOs) are the most technically challenging lesion that interventional cardiologists might face, and treatment of these lesions will have great effect on future percutaneous coronary intervention (PCI) success. Despite notable advances in the procedural and medical outcomes of percutaneous revascularization, CTO remains the unresolved problem in interventional cardiology.
Objective: To detect the pre-interventional predictors for procedural success of PCI of CTO and assess improvement of Left ventricular ejection fraction after successful PCI of CTO.
Methods: 52 Patients with CTO of more than 3 months duration having significant angina (Class III / IV) or recent acceleration of previously chronic stable angina admitted to zagazig university hospital and Kobry El-Kobba Military Hospital during period from januray 2017 till januray 2018 were included in the study.

Results: Predictors of technical success in CTO intervention were coronary artery diameter > 3mm , short CTO length less than 20mm , tapered CTO stump, absence of calcificlesion , bending angle less than 45 degree and prescence of microchannels. While small coronary artery diameter >3mm, CTO length more than 20mm , presence of bridging collaterals and high J-CTO score were predictors of technical failure .
Conclusion: PCI for coronary CTO should be performed for documented viable myocardium in the territory supplied by the chronicaly occluded artery. Proper evaluation of the clinical and angiographic characteristics of the patient to choose the proper plan for the recanalization. Success of PCI to CTO cause significant increase left ventricular ejection fraction.