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Summary and ConclusionTotally occluded coronary arteries still remain as a major challenge and unresolved dilemma for interventional cardiologists and they represent the most common cause of referral to coronary bypass surgery.Although successful revascularization of total coronary occlusions improves anginal status, exercise capacity, left ventricular function and reduces the need for late CABG, however PCI of total occlusions is associated with lower success rates (43% to 73%), higher equipment cost, increased radiation exposure and higher restenosis and reocclusion rates during follow up compared to PCI of non-total coronary lesions.Proper selection of patients with total occlusions who are more likely to benefit from revascularization remains the single most important factor, that increases the chance of angiographic and procedure success of PCI, and identifying the factors, that can predict the success of PCI in total coronary occlusions will help to establish guidelines for proper patient selection and reduces the likelihood of PCI failure.This study aimed to evaluate the predictive value of success of various clinical, angiographic and technical factors in patients undergoing percutaneous coronary intervention for total coronary occlusions.This study included 100 patients with total coronary occlusion who were referred for PCI and had durations of occlusion that ranged between 3 days to 24 weeks. The success rate in this study was 75%.To identify the independent predictors of success, all predictors that were significantly associated with procedural success by univariate analysis were included in a multivariate stepwise regression analysis model which defined 4 angiographic predictors and one clinical predictor as independent predictors of success:-1. Absence of intracoronary bridging collaterals.2. An occlusion length <13 mm.3. Tapered morphology of the stump.4. Reference lumen diameter of occluded vessel (target vessel size) of > 2.8mm.5. Duration of occlusion < 3 months.The results of this study came in agreement with many similar studies that evaluated predictors of success or failure and disagreed with other studies due to variability in selection criteria of patients and their numbers, variability in operator techniques, devices and experience and also due to differences in definitions of chronic total occlusions.The present study found that inability to cross the occlusion with guidewire was the commonest cause of procedural failure (80%) which was in agreement with other similar studies.The results of this study also found that PCI of total coronary occlusion was associated with low incidence of major adverse cardiac events ((3%, one death and 2 Q- wave MI)) and came in agreement with other studies which supports the concept that PCI of total coronary occlusions is a safe and low risk procedure.ConclusionWe concluded from our study that PCI of total coronary occlusions is a relatively safe and low risk procedure that requires careful selection of patients to improve the success rate, and in patients with total coronary occlusions the following specific angiographic and clinical characteristics were found to be an independent predictors of success and can represent guidelines for patient selection:1. Absence of intracoronary bridging collaterals.2. An occlusion length < 13 mm.3. Tapered morphology of the stump.4. Reference lumen diameter of occluded vessel (target vessel size) > 2.8 mm.5. An occlusion duration < 3 months.RecommendationsSo, we recommend that in PCI of total coronary occlusions, selection of patients with absent intracoronary bridging collaterals, occlusion length < 13mm, tapered morphology of stump, reference lumen diameter of occluded vessel > 2.8 mm and patients with occlusion duration < 3 months can significantly improve success rate and reduce the likelihood of PCI failure.We also recommend evaluating predictors of success in further studies with the use of special recanalization devices and new stiffer guidewires.ReferencesAlderman E, Stadius M . The angiographic definitions of the Bypass Angioplasty Revascularization Investigation. Coron Artery Dis 1992; 3: 1189-1207.Al suwaidi J, Berger PB, Holmes DR, et al . Coronary artery stents. 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