The Study On Clinical Efficacy Of Percutaneous Coronary Intervention Of CTO Lesion And Non-CTO Lesion In Patients With Chronic Total Occlusion(CTO)

Objectives:The major objective is to evaluate the procedural and clinical efficacy after percutaneous coronary intervention(PCI)of chronic total occlusion(CTO)lesion and non-CTO lesion in patients with coronary chronic total occlusion.Secondary objectives were comparing the in hospital outcomes and peri-procedural complication rate between groups.Simultaneously the efficacy of optimal medical therapy,PCI and CABG on treatment of CTO lesions are also analyzed.The baseline clinical characteristics,angiographic characteristics and procedural characteristics of CTO patients are also discussed.Background:With improved lifestyle of people,the incidence of coronary artery disease is gradually increasing.The patient receiving coronary angiography is also increasing.CTO is found in 15-20% of people undergoing diagnostic catheterization,and the prevalence is much higher among individuals with history of coronary artery disease.CTO is the result of atherosclerotic changes in coronary artery causing increased plaque burden leading to complete occlusion of the artery with time.It is defined as100% stenosis of coronary artery diagnosed by coronary angiography with TIMI flow grade 0.The duration of occlusion should be more than 3 months,which can be estimated via initial onset of symptoms,or increased frequency of angina or previous history of myocardial infarction or total occlusion revealed by coronary angiography.The chronic occlusion is a slow process.Long term ischemia promotes collateral circulation.The relatively patent collateral circulation is like 90% stenosis.However,myocardial ischemia can occur when the oxygen demand is more,and patient can feel angina or clinical manifestations of cardiac insufficiency.Long term myocardial ischemia leads to myocardial ischemia,myocardial remodeling and cardiac dysfunction which can affect the quality of life and prognosis.Early management is important is improving these symptoms.The treatment of CTO include medical therapy,PCI and CABG.Recently,with the improvements in PCI related tools and techniques,especially use of drug eluting stents and increased operators' experience CTO PCI success rate is increasing,complication rate is decreasing.CTO revascularization by PCI improves patients' quality of life,cardiac function,and decreases need for CABG and mortality.Several factors influence CTO PCI.They include CTO duration,length of occlusion,proximal end morphology calcification,and collateral circulation.Many scoring systems have been established to assess CTO PCI success.The most commonly used is J-CTO score.Other scoring system include CT-RECTOR score,PROGRESS CTO score,CL score,ORA score etc.The inability to pass guidewire is one of the most important factor of CTO PCI failure.Sometimes,CTO PCI couldn't be done because pre dilatation balloon couldn't pass the lesion due to heavy calcification.Understanding the CTO PCI complications also helps in achieving CTO PCI success.Method:A consecutive 261 patients from January to December of 2016,diagnosed with coronary chronic total occlusion in the cardiovascular department of our hospital were enrolled in our study.The inclusion criteria includes 100% stenosis by coronary angiography,TIMI flow 0,occlusion duration more than 3 months and occluded artery diameter ? 2.5 cm.The exclusion criteria includes acute myocardial infarction within 3 months,previous history of stroke for 6 months,severe renal insufficiency,hemorrhage,coagulation disorder,previous PCI or CABG history,allergy to contrast,aspirin or clopidogrel.Non-CTO lesion is defined as ? 70% stenosis of major vessels.CTO PCI success is defined as residual stenosis < 50% after PTCA of target lesion,and < 30% stenosis after stenting with TIMI 3 and without any complications.Majoradverse cardiovascular events(MACE)include cardiogenic death,myocardial infarction,and repeated angina induced target vessel revascularization.Post-procedure MI was defined as new Q wave in ECG or CK-MB increased more than 5 times.All these patients initially divided into two groups based on angiographic report: single vessel disease(SVD)group and non-single vessel disease(non-SVD)group.Then,they were divided into optimal medical therapy(OMT)group,PCI group and CABG group.PCI group further divided into PCI of CTO lesion(CTO PCI group)and PCI of non-CTO lesion(non-CTO PCI group).CTO PCI group has PCI success group and PCI failure group.PCI success group was treated by either PTCA or stenting.Each patient was followed up at 12 months and 24 months.Follow up methods included outpatient follow up,messaging or telephone follow up.Follow up includes primary study endpoint and secondary study endpoints.Primary study endpoints were MACE,target vessel revascularization,non-target vessel revascularization,CABG and all cause death.Secondary endpoints were post-procedure MI,coronary perforation,in-stent thrombosis,bleeding,access site complications,and contrast nephropathy.Finally,data were analyzed using SPSS 20.0software and applying t test and chi square test.P< 0.05 was considered as statistically significant.Result:A total of 261 patients enrolled as CTO patients,mean age was 62.83 years,70.1% were male patients.The most common risk factor was hypertension(64.4%),followed by smoking(48.3%),diabetes(34.5%)and hyperlipidaemia.(27.2%).Patients in OMT group were mostly refused PCI treatment,agreed to conservative medical therapy.CABG group patients were mostly triple vessel disease,comparatively complex lesion,considered high risk PCI and increased rate of complications.SVD,DVD and TVD were present in 39(14.94%),81(31.03%)and141(54.02%)respectively.In non-SVD group,PCI of CTO lesion performed in 108 patients,while PCI of non-CTO lesion performed in 44 patients.All patients were stented in non-CTO PCI group.The first attempt of CTO revascularization in 16 patients failed.Reasons included unable to pass guidewire or cross balloon,severe calcification,coronary dissection,guidewire passing into false lumen,coronary perforation and so on.Among 92 patients with CTO PCI success,4 patients undergone PTCA,and 88 patients undergone stenting.In hospital outcomes were relatively higher in CTO PCI group,7 patients had access site complication,3 patients coronary dissection,1 patient contrast nephropathy.Comparing the long term efficacy,the rate of MACE and non-target vessel revascularization were higher in CTO PCI than non-CTO PCI group,and were statistically significant(p < 0.05).The rate of target vessel revascularization,CABG and all cause death were also lower in CTO PCI group,but was not statistically significant(p > 0.05).Discussion:With the advancement in PCI related techniques and increased operator's experience,success rate of CTO PCI has increased.CTO PCI success improves patients' quality of life,decreases myocardial ischemia induced angina,improves heart function,prevents cardiac arrhythmias,and decreases need of anti-anginal medications and mortality.This study showed long term prognosis of CTO PCI success patients was better.4 patients in OMT group were expired and MACE rate was higher in this group.This is due to refusal of PCI treatment by the patient although they were indicated to PCI treatment or due to poor patient financial condition.Literates reported only 1/3 of patients with CTO was intervened to their CTO lesion,but,we have managed to almost 2/3 of patients by PCI except those with CTO PCI failure.DECISION-CTO trial randomized 834 patients and divided into CTO PCI + OMT group and OMT group,follow up for 3.1 years and reported similar clinical efficacy and quality of life between these groups.According ACC/AHA appropriate use criteria,if patients had better symptomatic relief,better functional and quality of life,they were indicated to revascularization.If there are high risk,complex procedure,high cost,high radiation,less symptomatic relief,those patients can be recommended medical therapy.Before undergoing CTO PCI,following things should be considered:(1)whether the patient had myocardial ischemia induced angina;(2)rate of CTO PCI success;(3)risk and complications of CTO PCI.Proper planning should be done to get higher CTO PCI success rate.The assisted modalities can be used in certain cases.These modalities include intravascular ultrasonography(IVUS),rotational atherectomy(RA),and excimer laser coronary atherectomy(ELCA).This study has certain limitation,the sample size is less,single-centered,several bias(mostly selection bias),short follow up duration.The radiation exposure dose,operational duration and contrast dose were also not calculated.This can have influence on procedural and clinical efficacy.Conclusion:(1)The rate of MACE,non-target vessel revascularization,CABG and all cause death are lower if PCI is successfully performed in CTO patients.(2)CTO PCI success also improves quality of live,decreases myocardial ischemia induced angina,and overall improves long term efficacy.(3)if the patients improves with symptoms,functional ability and quality of life,revascularization of CTO can be considered.Optimal medical therapy can be considered if there is high procedural risk,complex procedure,high cost,increased radiation,and improved angina symptoms,(4)proper planning should be considered before undergoing CTO PCI and assisted examinations(such as IVUS,RA and laser therapy)should be performed in selected cases,which will increase success rate and decrease complication rate.