| Background:Coronary chronic total occlusion (OTC) is the end stage of coronary artery atherosclerosis, account for one third of the disease confirmed by coronary angiography. CTO can result in myocardium ischemia, myocardiolysis, reduction of the number of myocardial cells, ventricular remodeling which lead to decreased myocardium contractile, reduction of quality of life and poor prognosis. Medication alone for OTC treatment may only relieve the clinical symptoms while have little effect on long-term heart function and survival rate improvement. Percutaneous coronary intervention (PCI) is one therapeutic procedure used to recanalize vessels with total occlusion, gain blood flow reperfusion, improve myocardial contractile function and pump function, inhibit left ventricular remodeling, decrease adverse cardiac events. The successful rate in CTO patients by PCI procedure was lower than that in non-CTO patients. Revasculization for CTO lesions is more difficult and may be influenced by clinical baseline characteristics, lesions characteristics, intervention equipments and physician's manipulation techniques etc. Along with the development of interventional techniques and technologies, as well as physician's manipulation techniques, successful rates for PCI procedure of CTO lesions were significantly increased, however, CTO recanalization is still accepted as extremely challenging procedure in cardiovascular PCI treatments.CTO revasculization can be performed by percutaneous transluminal coronary aginoplasty (PTCA), bare metal stent (BMS) or drug-eluting stent (DES). Long-term outcomes as cumulative survival rate, major adverse cardiac events (MACE), incidence of restenosis and reocclusion are still under debate based on different procedures and technologies. Therefore, it is important to scientifically evaluate the effectiveness and influential factors for CTO interventional treatment.Objectives:This study aimed to systematically review and overall assess for PCI procedure in CTO patients. Five different aspects were studied: (1) Potential influential factors to influence successful rate of PCI procedure; (2) Short-term (in-hospital) outcomes for PCI procedure; (3) Long-term outcomes for PCI procedure; (4) Comparison of long term outcomes between PTCA and stent implantation; (5) Comparison of long term outcomes between drug eluting stents and bare metal stents.Methods:By systematic review and meta analysis, we analyzed pertinent articles on CTO recanalization. Data were extracted and assessed by two independent clinical experts, pooled and analyzed by fixed effects model and random effects model. Heterogeneity was assessed using the I2 test, Q test, L'abbe and Galbraith. An I2 value > 50% was considered as heterogeneity. We searched Embase,PubMed,Medline,Ovid,CCTR,CNKI,CMBdisc, and with additional manual search for related meeting abstracts and websites including American Heart Association,American College of Cardiology,European Society of Cardiology, and national postgraduate thesis pool ( from January 1990 to December 2009). Software for analysis was Comprehensive Meta Analysis 2.0 and Metanalysis1.0.Results:(1) Totally 16 articles were included on CTO revasculization to compare clinical and lesion baseline characteristics between successful CTO recanalization (CTO success groups) and failed CTO recanalization (CTO failure groups). These studies encompassed 9065 CTO patients with mean successful rate for CTO recanalization of 73.9%. Eight clinical baseline characteristics (age, gender, hypertension, hyperlipidemia, diabetes mellitus, smoker, previous myocardial infarction history, previous coronary artery bypass graft surgery (CABG) history) and six lesion baseline characteristics ( lesion length, left ventricular ejection fraction, multi-vessel coronary disease, left anterior descending artery lesion, Circumflex artery lesion, right coronary artery disease lesion) were analyzed by meta analysis to assess discrepancies between two treatment groups. Among these, weighted average age difference between two groups was 0.083 (95%CI 0.132~0.034,P=0.001), weighted average lesion length difference was -0.782 ( 95% CI -1.499~-0.065, P=0.033). Low CTO success was associated with previous CABG history (odd ratio [OR]0.707, 95%CI 0.578~0.865,P=0.001), multi-vessel diseases (OR 0.649, 95%CI 0.554~0.761, P<0.001),and right coronary artery disease lesion(OR 0.756,95%CI 0.597~0.958,P=0.021).(2) Totally 9 articles compared in hospital outcomes between CTO success groups and CTO failure groups. In-hospital mortality, major adverse cardiac events (MACE), subsequent CABG, recurrent acute myocardial infarction and subsequent PCI during hospitalization were analyzed in CTO patients by meta analysis. CTO success was associated with lower in-hospital mortality (OR 0.339, 95% CI 0.204~0.563,P<0.001), lower in-hospital MACE (OR 0.474, 95% CI 0.334~0.673,P<0.001), lower in-hospital acute CABG (OR 0.112, 95% CI 0.034~0.375,P<0.001).(3) Total 16 articles were studied on long term outcomes (follow up for more than 1 year) between CTO success groups and CTO failure groups. Six follow up variables as MACE, MI, all-cause death, angina pectoris, subsequent CABG and accumulative survival rate were analyzed by meta analysis. CTO success was associated with significant reduction in MACE (OR 0.689, 95% CI 0.488~0.971,P=0.034), recurrent MI (OR 0.578, 95% CI 0.387~0.864,P=0.008), all-cause death (OR 0.501, 95% CI 0.384~0.654,P<0.001), incidence of angina (OR 0.477, 95%CI 0.340~0.670,P<0.001), subsequent CABG (OR 0.212, 95% CI 0.175~0.257,P<0.001), cumulative survival rate (HR 0.595, 95% CI 0.488~0.791,P<0.001).(4) Totally 8 articles compared long term outcomes between PTCA and BMS groups, encompassed 2865 CTO patients. Six follow up variables (followed up for more than six months) as mortality, subsequent CABG, re-occlusion rate, re-stenosis rate, subsequent PCI and target lesion revasculization (TLR) were analyzed by meta analysis. Compared with BMS intervention, PTCA was associated with significant higher rate of re-occlusion (OR 3.478, 95% CI 1.966~6.153,P<0.001), re-stenosis (OR 3.028, 95% CI 1.354~6.774,P=0.007), subsequent PTCA (OR 3.017, 95% CI 1.957~4.653,P<0.001), TLR (OR 2.57, 95% CI 1.762~3.748,P<0.001).(5) Totally 12 articles compared long term outcomes between BMS groups and DES groups, encompassed 3605 CTO patients. During the long-term follow up, six variables as MACE, MI, all-cause death, subsequent CABG, accumulated MACE-free survival rate, re-stenosis/ re-occlusion rate were analyzed by meta analysis. Compared with patients in DES groups, patients in BMS groups had significant higher MACE (OR 3.513, 95% CI 2.297~5.374,P<0.001), subsequent CABG (OR 4.614, 95% CI 1.498~14.219,P=0.008), re-stenosis/ re-occlusion rate (OR 11.825, 95% CI 4.192~33.355,P<0.001),TLR(OR 4.343 ,95%CI 2.538~7.304,P<0.001),TVR(OR 2.983,95%CI 1.958~4.543,P<0.001),while lower MACE-free survival rate (HR 0.699, 95% CI 0.569 ~0.858 ,P=0.001).Conclusions:(1) Clinical baseline characteristics such as age, previous CABG history and lesion baseline characteristics such as lesion length, multi-vessel diseases may be the important factors to influence successful rate of CTO recanalization. (2) The in-hospital mortality, MACE, and incidence of subsequent CABG for PTCA procedure were significantly lower for CTO patients in CTO success groups than those in CTO failure group. (3) Compared with CTO failure patients, all six follow up variables (MACE, recurrent myocardial infarction, all-cause death, recurrent angina pectoris, subsequent CABG, accumulated survival rate) showed benefit for CTO success patients. (4) Four follow up variables as the incidence of re-occlusion, re-stenosis, subsequent PTCA and TLR were significantly lower for BMS implantation than for PTCA procedure. (5) Variables as MACE, subsequent CABG, re-stenosis/ re-occlusion rate were higher while accumulated MACE-free survival rate was significantly lower in BMS groups than in DES groups and all-cause death, recurrent myocardial infarction were not significantly between two groups.
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