Background: Computed tomography coronary angiography(CTCA) can be useful in procedure planning for CTO PCI by identifying factors known to influence PCI success rates, such as calcification, severe tortuosity and length of the occluded segment. Percutaneous coronary intervention for CTO is considered to be one of the most challenging procedures of interventional cardiology, and in the earlier studies, successful recanalization rates of CTO ranged from 51% to 74%. However, with improved operator experience and the development of novel equipment and techniques, procedural success rates have been increased, which brings an increasing number of CTO into a treatable category. Patients and Methods:  An exploratory pilot study was conducted on 40 patients using retrograde wire approach with various strategies by highly experienced CTO operators in Ain Shams University hospitals and in Kobry Elkobba Military hospital from August 2015 to 2017. Results: According to the results CTOs were divided into two groups, group1 with successful retrograde PCI in 32 pts. (80%), and group 2 with failed-retrograde PCI in 8 pts. (20%) All CTOs were correctly identified by MIP,MPR,cMPR images. Most of the CTOs were located in the proximal 21 patients 52.5% then mid 14 patients 35% ostial 3 patients 7.5% and lastly distal 2 patients 5%. In failed group there were more calcified plaques. There was more calcification in the CTOs segments (p=0.005). Ten arc-calcified and two circular-calcified lesions were identified only 4 from ten patients (40%) had arc calcified Plaques which were successfully recanalized and 6 patients 60% failed. In circular-calcified lesions one patient (50%) succeeded and one failed. Proximal artery tortuosity between two groups showed a significant difference (p=0.000). Conclusion: Complex CTO lesion morphology is still an important issue for CTO-PCI procedural success, and further improvement of technologies (MDCT) and medical devices, such as guide wires and catheters are required to improve the success rate.