Improved recovery of regional left ventricular function after PCI of chronic total occlusion in STEMI patients: a cardiovascular magnetic resonance study of the randomized controlled EXPLORE trial

Who Should Undergo Chronic Total Occlusions Percutaneous Coronary Intervention and When?: An Evidence-Based Approach to the Patient Referred for Percutaneous Coronary Intervention of Chronic Total Occlusion

Chronic total occlusions (CTO) of the coronary arteries are common among patients presenting to the cardiac catheterization laboratory, and data suggests a worse overall prognosis in patients with CTOs. Percutaneous coronary intervention (PCI) of CTOs has been shown to improve anginal symptoms in observational studies and in a limited number of randomized trials. However, CTO PCI has not been shown to lead to a reduction in other important end points such as myocardial infarction or death. Furthermore, despite recent advances in the field, CTO PCI still carries higher risks and a lower likelihood of success compared with non-CTO PCI. Thus, determining which patients may be appropriate for CTO PCI is challenging and must involve a comprehensive risk-benefit analysis and discussion with the patient. Therefore, we review the currently available data regarding CTO PCI, including the clinical outcomes, the role of preprocedural ischemia testing, and various procedural success and risk stratification scores. Finally, we present our approach to the patient referred for CTO PCI.

Ten-Year Outcome of Recanalization or Medical Therapy for Concomitant Chronic Total Occlusion After Myocardial Infarction

BACKGROUND

The EXPLORE (Evaluating Xience and Left Ventricular Function in PCI on Occlusions After STEMI) trial was the first and only randomized trial investigating chronic total occlusion (CTO) percutaneous coronary intervention (PCI) early after primary PCI for ST-segment-elevation myocardial infarction, compared with medical therapy for the CTO. We performed a 10-year follow-up of EXPLORE to investigate long-term safety and clinical impact of CTO PCI after ST-segment-elevation myocardial infarction, compared with no-CTO PCI.

METHODS AND RESULTS

In EXPLORE, 302 patients post-ST-segment-elevation myocardial infarction with concurrent CTO were randomized to CTO PCI within ≈1 week or no-CTO PCI. We performed an extended clinical follow-up for the primary end point of major adverse cardiac events, consisting of cardiovascular death, coronary artery bypass grafting, or myocardial infarction. Secondary end points included all-cause death, angina, and dyspnea. Median follow-up was 10 years (interquartile range, 8-11 years). The primary end point occurred in 25% of patients with CTO PCI and in 24% of patients with no-CTO PCI (hazard ratio [HR], 1.11 [95% CI, 0.70-1.76]). Cardiovascular mortality was higher in the CTO PCI group (HR, 2.09 [95% CI, 1.10-2.50]), but all-cause death was similar (HR, 1.53 [95% CI, 0.93-2.50]). Dyspnea relief was more frequent after CTO PCI (83% versus 65%, P=0.005), with no significant difference in angina.

CONCLUSIONS

This 10-year follow-up of patients post-ST-segment-elevation myocardial infarction randomized to CTO PCI or no-CTO PCI demonstrated no clinical benefit of CTO PCI in major adverse cardiac events or overall mortality. However, CTO PCI was associated with a higher cardiovascular mortality compared with no-CTO PCI. Our long-term data support a careful weighing of effective symptom relief against an elevated cardiovascular mortality risk in CTO PCI decisions.

REGISTRATION

URL: https://www.trialregister.nl; Unique identifier: NTR1108.

Coronary Chronic Total Occlusion Revascularization: When, Who and How?

Coronary chronic total occlusions (CTO) are an increasingly frequent entity in clinical practice and represent a challenging percutaneous coronary intervention (PCI) scenario. Despite data from randomized trials that have not yet demonstrated a clear benefit of CTO recanalization, the widespread of CTO-PCI has substantially increased. The improvement in operators' techniques, equipment, and training programs has led to an improvement in the success rate and safety of these procedures, which will represent an important field of future development of PCI. The present review will summarize clinical outcomes and technical and safety issues of CTO revascularization with the aim to guide clinical daily cath-lab practice.

Evaluation and management of patients with coronary chronic total occlusions considered for revascularisation. A clinical consensus statement of the European Association of Percutaneous Cardiovascular Interventions (EAPCI) of the ESC, the European Association of Cardiovascular Imaging (EACVI) of the ESC, and the ESC Working Group on Cardiovascular Surgery

Chronic total occlusions (CTOs) of coronary arteries can be found in the context of chronic or acute coronary syndromes; sometimes they are an incidental finding in those apparently healthy individuals undergoing imaging for preoperative risk assessment. Recently, the invasive management of CTOs has made impressive progress due to sophisticated preinterventional assessment, including advanced non-invasive imaging, the availability of novel and dedicated tools for CTO percutaneous coronary intervention (PCI), and experienced interventionalists working in specialised centres. Thus, it is crucial that referring physicians who see patients with CTO be aware of recent developments and of the initial evaluation requirements for such patients. Besides a careful history and clinical examination, electrocardiograms, exercise tests, and non-invasive imaging modalities are important for selecting the patients most suitable for CTO PCI, while others may be referred to coronary artery bypass graft or optimal medical therapy only. While CTO PCI improves angina and reduces the use of antianginal drugs in patients with symptoms and proven ischaemia, hibernation and/or wall motion abnormalities at baseline or during stress, the effect of CTO PCI on major cardiovascular events is still controversial. This clinical consensus statement specifically focuses on referring physicians, providing a comprehensive algorithm for the preinterventional evaluation of patients with CTO and the current evidence for the clinical effectiveness of the procedure. The proposed care track has been developed by members and with the support of the European Association of Percutaneous Cardiovascular Interventions (EAPCI), the European Association of Cardiovascular Imaging (EACVI), and the European Society of Cardiology (ESC) Working Group on Cardiovascular Surgery.

Percutaneous Coronary Intervention for Chronic Total Occlusion-Contemporary Approach and Future Directions

In the aging society, the issue of coronary chronic total occlusion (CTO) has become a challenge for invasive cardiologists. Despite the lack of clear indications in European and American guidelines, the rates of percutaneous coronary interventions (PCI) for CTO increased over the last years. Well-conducted randomized clinical trials (RCT) and large observational studies brought significant and substantial progress in many CTO blind spots. However, the results regarding the rationale behind revascularization and the long-term benefit of CTO are inconclusive. Knowing the uncertainties regarding PCI CTO, our work sought to sum up and provide a comprehensive review of the latest evidence on percutaneous recanalization of coronary artery chronic total occlusion.

Why and How Should We Treat Chronic Total Occlusion? Evolution of State-of-the-Art Methods and Future Directions

Chronic total occlusions are considered the most complex coronary lesion in interventional cardiology. The absence of visible lumen on angiography obscures the vessel course and makes vessel wiring unlikely with conventional techniques. Often a source of severe ischemia, chronic occlusions are also markers of advanced atherosclerosis that brings other complex features including lesion length, bifurcations, calcification, adverse vessel remodelling, distal disease, and anatomic distortion from previous bypass grafting. Often advanced atherosclerosis is associated with patient characteristics like left ventricular dysfunction, previous coronary bypass surgery, or multivessel disease that increase procedural demands and hazards. To accommodate these challenges new techniques and dedicated technologies have been developed. When applied to appropriate patients, these advances have improved procedural success, safety, and outcomes. Our aim is to provide the general cardiologist with an overview of these advances that can serve as a basis for counselling patients considered for revascularization.

Revascularization of chronic total occlusion coronary artery and cardiac regeneration

Coronary chronic total occlusion (CTO) contributes to the progression of heart failure in patients with ischemic cardiomyopathy. Randomized controlled trials demonstrated that percutaneous coronary intervention (PCI) for CTO significantly improves angina symptoms and quality of life but fails to reduce clinical events compared with optimal medical therapy. Even so, intervening physicians strongly support CTO-PCI. Cardiac regeneration therapy after CTO-PCI should be a promising approach to improving the prognosis of ischemic cardiomyopathy. However, the relationship between CTO revascularization and cardiac regeneration has rarely been studied, and experimental studies on cardiac regeneration usually employ rodent models with permanent ligation of the coronary artery rather than reopening of the occlusive artery. Limited early-stage clinical trials demonstrated that cell therapy for cardiac regeneration in ischemic cardiomyopathy reduces scar size, reverses cardiac remodeling, and promotes angiogenesis. This review focuses on the status quo of CTO-PCI in ischemic cardiomyopathy and the clinical prospect of cardiac regeneration in this setting.

CTO in Contemporary PCI

Percutaneous Coronary Intervention (PCI) of Chronic Total Occlusions (CTO) represents the most challenging procedure in modern endovascular treatments. In recent years, the success rate of CTO PCI has substantially improved, owing to increasing operator expertise and advancements in CTO equipment and algorithms as well as the development of expert consensus documents. In this review, we summarize existing evidence for CTO PCI, its success/ risk prediction scoring tools, procedural principles and complications and provide an insight into the future role of CTO PCI.

Update on chronic total occlusion percutaneous coronary intervention

Chronic total occlusion (CTO) percutaneous coronary interventions (PCI) can be challenging to perform. The main indication for CTO PCI is to improve symptoms. Several contemporary studies have reported high CTO PCI success rates at experienced centers but success rates in all-comer registries remain low. Several scores can estimate the difficulty and the likelihood of success of CTO PCI. Dual arterial access and use of CTO crossing algorithms can improve the success and safety of CTO PCI. Intracoronary imaging can optimize stent expansion and minimize adverse cardiovascular events. While complications are more common in CTO PCI, careful planning and prompt diagnosis and treatment can prevent them or minimize their adverse consequences. In this article, we review contemporary data on the indications, safety and efficacy of CTO PCI.

Recovery of right ventricular function and strain in patients with ST-segment elevation myocardial infarction and concurrent chronic total occlusion

The right ventricle (RV) is frequently involved in ST-segment elevation myocardial infarction (STEMI) when the culprit or concurrent chronic total occlusion (CTO) is located in the right coronary artery (RCA). We investigated RV function recovery in STEMI-patients with concurrent CTO. In EXPLORE, STEMI-patients with concurrent CTO were randomized to CTO percutaneous coronary intervention (PCI) or no CTO-PCI. We analyzed 174 EXPLORE patients with serial cardiovascular magnetic resonance imaging RV data (baseline and 4-month follow-up), divided into three groups: CTO-RCA (CTO in RCA, culprit in non-RCA; n = 89), IRA-RCA (infarct related artery [IRA] in RCA, CTO in non-RCA; n = 56), and no-RCA (culprit and CTO not in RCA; n = 29). Tricuspid annular plane systolic excursion (TAPSE), RV ejection fraction (RVEF), RV global longitudinal strain (GLS) and free wall longitudinal strain (FWLS) were measured. We found that RV strain and TAPSE improved in IRA-RCA and CTO-RCA (irrespective of CTO-PCI) at follow-up, but not in no-RCA. Only RV FWLS was different among groups at baseline, which was lower in IRA-RCA than no-RCA (− 26.0 ± 8.3% versus − 31.0 ± 6.4%, p = 0.006). Baseline RVEF, RV end-diastolic volume and TAPSE were associated with RVEF at 4 months. RV function parameters were not predictive of 4 year mortality, although RV GLS showed additional predictive value for New York Heart Association Classification > 1 at 4 months. In conclusion, RV parameters significantly improved in patients with acute or chronic RCA occlusion, but not in no-RCA patients. RV FWLS was the only RV parameter able to discriminate between acute ischemic and non-ischemic myocardium. Moreover, RV GLS was independently predictive for functional status.

Infarct-related chronic total coronary occlusion and the risk of ventricular tachyarrhythmic events in out-of-hospital cardiac arrest survivors

Introduction

Chronic total coronary occlusion (CTO) has been identified as a risk factor for ventricular arrhythmias, especially a CTO in an infarct-related artery (IRA). This study aimed to evaluate the effect of an IRA-CTO on the occurrence of ventricular tachyarrhythmic events (VTEs) in out-of-hospital cardiac arrest survivors without ST-segment elevation.

Methods

We conducted a post hoc analysis of the COACT trial, a multicentre randomised controlled trial. Patients were included when they survived index hospitalisation after cardiac arrest and demonstrated coronary artery disease on coronary angiography. The primary endpoint was the occurrence of a VTE, defined as appropriate implantable cardioverter-defibrillator (ICD) therapy, sustained ventricular tachyarrhythmia or sudden cardiac death.

Results

A total of 163 patients from ten centres were included. Unrevascularised IRA-CTO in a main vessel was present in 43 patients (26%). Overall, 61% of the study population received an ICD for secondary prevention. During a follow-up of 1 year, 12 patients (7.4%) experienced at least one VTE. The cumulative incidence rate of VTEs was higher in patients with an IRA-CTO compared to patients without an IRA-CTO (17.4% vs 5.6%, log-rank p = 0.03). However, multivariable analysis only identified left ventricular ejection fraction < 35% as an independent factor associated with VTEs (adjusted hazard ratio 8.7, 95% confidence interval 2.2–35.4). A subanalysis focusing on CTO, with or without an infarct in the CTO territory, did not change the results.

Conclusion

In out-of-hospital cardiac arrest survivors with coronary artery disease without ST-segment elevation, an IRA-CTO was not an independent factor associated with VTEs in the 1st year after the index event.

Supplementary Information

The online version of this article (10.1007/s12471-021-01578-3) contains supplementary material, which is available to authorized users.

Antegrade versus retrograde techniques for Chronic Total Occlusions (CTO): a review and comparison of techniques and outcomes

Introduction: As the field of chronic total occlusion percutaneous coronary intervention has evolved, technical approaches have evolved and been refined.Areas covered: In this review, we discuss the major techniques utilized in modern CTO PCI including antegrade wiring, antegrade dissection reentry, retrograde wiring, and retrograde dissection reentry. Retrograde techniques have been extensively studied in comparison to antegrade techniques. Retrograde techniques have contributed to increases in CTO PCI success rates and are generally used in higher complexity lesions. Observational data ssuggestincreased sshort-termcomplications in procedures requiring the use of retrograde techniques; however, llong-termCTO PCI durability and patient outcomes have been shown to be similar among procedures using antegrade only versus retrograde techniques.Expert opinion: Retrograde techniques play a vital role in the technical success of CTO PCI, particularly among more complex lesions and in patients with high burdens of comorbidities. Increases in procedural safety with equipment iteration and in the use of adjunctive imaging will play an important role in the selection of appropriate retrograde conduits and the overall success rates of CTO PCI.

Association of symptom status, myocardial viability, and clinical/anatomic risk on long-term outcomes after chronic total occlusion percutaneous coronary intervention

OBJECTIVES

This study aimed to examine the association of less-certain indication of chronic total occlusion percutaneous coronary intervention (CTO-PCI) with subsequent clinical outcomes.

BACKGROUND

The impact of patient symptoms, myocardial viability, and clinical and anatomic risk on long-term outcomes is underdetermined.

METHODS

Consecutive patients undergoing CTO-PCI at a large-volume single center between 2010 and 2013 were included. Central adjudication was used to assess the appropriateness of three prespecified indications. The primary outcome was the 5-year composite endpoint of death or myocardial infarction (MI).

RESULTS

Of 2,659 patients with 2,735 CTO lesions, the 348 (13.1%) asymptomatic patients, 164 (6.2%) patients without viable myocardium in the CTO territory, and 306 (11.5%) patients in whom the Synergy between PCI with Taxus and Cardiac Surgery Score II favored coronary artery bypass grafting (CABG) had higher 5-year death or MI compared with the rest patients in each category (12.0% vs. 8.6%, p = .04; 16.3% vs. 8.5%, p < .0001; 12.2% vs. 8.6%, p = .03), respectively. Multivariable regression analysis demonstrated that without symptom (hazard ratio: 1.51; 95% confidence interval: 1.06-2.15; p = .02), non-viable myocardium in CTO territory (hazard ratio: 1.77; 95% confidence interval: 1.16-2.72; p = .009), and deemed more favorable for CABG (hazard ratio:1.54; 95% confidence interval: 1.04-2.28; p = .03), but not the technical success (hazard ratio:0.85; 95% confidence interval: 0.62-1.18; p = .34), were independent predictors for the primary endpoint.

CONCLUSIONS

In this large cohort of CTO-PCI, those who were asymptomatic, non-viable myocardium in the CTO territory, or deemed more favorable for CABG were associated with higher risk of long-term mortality or MI.

Prognostic Impact of Percutaneous Coronary Intervention of Chronic Total Occlusion in Acute and Periprocedural Myocardial Infarction

Coronary chronic total occlusion (CTO) has gained increasing clinical attention as the most advanced form of coronary artery disease. Prior studies already indicated a clear association of CTO with adverse clinical outcomes, especially in patients with acute myocardial infarction (AMI) and concomitant CTO of the non-infarct-related coronary artery (non-IRA). Nevertheless, the prognostic impact of percutaneous coronary intervention (PCI) of CTO in the acute setting during AMI is still controversial. Due to the complexity of the CTO lesion, CTO-PCI leads to an increased risk of complications compared to non-occlusive coronary lesions. Therefore, this review outlines the prognostic impact of CTO-PCI in patients with AMI. In addition, the prognostic impact of periprocedural myocardial infarction caused by CTO-PCI will be discussed.

The Bioengineered Combo Dual-Therapy CD34 Antibody-Covered Sirolimus-Eluting Coronary Stent in Patients with Chronic Total Occlusion Evaluated by Clinical Outcome and Optical Coherence Tomography Imaging Analysis

We sought to determine the effects of the use of a Bioengineered Combo Dual-Therapy CD34 Antibody-Covered Sirolimus-Eluting Coronary Stent (Combo^® DTS) in patients with chronic total occlusion (CTO) by evaluating clinical outcomes and by performing an optical coherence tomography (OCT) analysis. We retrospectively analyzed data from 39 patients who had successfully undergone OCT-guided revascularization of a CTO being treated with a Combo^® DTS. Clinical assessment, angiography (with quantitative coronary angiography analysis) and OCT examination were performed at baseline and at follow-up. The median follow-up period was 189 days, ranging from 157 to 615 days. At follow-up, revascularization was required due to angiographic restenosis in 40% (14 of 35) of patients. OCT analysis detected neointima proliferation in 23 (76.6%) patients. Neointima formation was often associated with microvessels in 18 patients (60%). Neoatheroslcerosis was observed in 2 (6.6%) patients. Malapposition was found in 4 patients (13.3%), and stent fractures were found in 11 patients (36.6%). Rate of strut coverage was 96.3% at follow-up. In conclusion, the implantation of a Combo^® DTS after successful CTO recanalization was associated with a restenosis rate of 40% despite good stent implantation at baseline, proven by OCT. Neointima formation was found as a main contributor to restenosis. Nevertheless, we observed a low rate of major cardiovascular events in our follow-up.

Percutaneous coronary intervention versus medical therapy for chronic total coronary occlusions: a systematic review and meta-analysis of randomised trials

BACKGROUND

The results of chronic total occlusion percutaneous coronary intervention (CTO-PCI) trials are inconclusive. Therefore, we studied whether CTO-PCI leads to improvement of clinical endpoints and patient symptoms when combining all available randomised data.

METHODS AND RESULTS

This meta-analysis was registered in PROSPERO prior to starting. We performed a literature search and identified all randomised trials comparing CTO-PCI to optimal medical therapy alone (OMT). A total of five trials were included, comprising 1790 CTO patients, of whom 964 were randomised to PCI and 826 to OMT. The all-cause mortality was comparable between groups at 1‑year [risk ratio (RR) 1.70, 95% confidence interval (CI) 0.50-5.80, p = 0.40] and at 4‑year follow-up (RR 1.14, 95% CI 0.38-3.40, p = 0.81). There was no difference in the incidence of major adverse cardiac events (MACE) between groups at 1 year (RR 0.69, 95% CI 0.36-1.33, p = 0.27) and at 4 years (RR 0.85, 95% CI 0.60-1.22, p = 0.38). Left ventricular function and volumes at follow-up were comparable between groups. However, the PCI group had fewer target lesion revascularisations (RR 0.28, 95% CI 0.15-0.52, p < 0.001) and was more frequently free of angina at 1‑year follow-up (RR 0.65, 95% CI 0.50-0.84, p = 0.001), although the scores on the subscales of the Seattle Angina Questionnaire were comparable.

CONCLUSION

In conclusion, in this meta-analysis of 1790 CTO patients, CTO-PCI did not lead to an improvement in survival or in MACE as reported at long-term follow-up of up to 4 years, or to improvement of left ventricular function. However, CTO-PCI resulted in less angina and fewer target lesion revascularisations compared to OMT.

Vulnerability for ventricular arrhythmias in patients with chronic coronary total occlusion

INTRODUCTION

The presence of a chronic total occlusion (CTO) is associated with an increased risk of ventricular arrhythmias.

AREAS COVERED

This review provides an overview of the relationship between CTO and ventricular arrhythmias, arrhythmogenic mechanisms, and the effect of revascularization.

EXPERT OPINION

Studies in recipients of an implantable cardioverter-defibrillator (ICD) have shown that a CTO is an independent predictor of appropriate ICD therapy. The myocardial territory supplied by a CTO is a pro-arrhythmogenic milieu characterized by scar tissue, large scar border zone, hibernating myocardium, residual ischemia despite collaterals, areas of slow conduction, and heterogeneity in repolarization. Restoring coronary flow by revascularization might be associated with electrical homogenization as reflected by a decrease in QT(c) dispersion, decrease in T wave peak-to-end interval, reduction of late potentials, and decrease in scar border zone area. Future research should explore whether CTO revascularization results in a lower burden of ventricular arrhythmias. Furthermore, risk stratification of CTO patients without severe LV dysfunction is interesting to identify potential ICD candidates. Potential tools for risk stratification are the use of electrocardiographic parameters, body surface mapping, electrophysiological study, and close rhythm monitoring using an insertable cardiac monitor.

The success of opening concurrent chronic total occlusion lesion to improve cardiac function trial in patients with multi-vessel disease (SOS-moral): Study protocol of a prospective multicenter study

AIMS

The purpose of the present trial is to determine whether opening co-existing chronic total occlusions (CTOs) using percutaneous coronary interventions (PCIs) improves cardiac function in patients with multi-vessel disease (MVD). Patients with MVD are defined as having at least one additional major vessel exhibiting no less than 75% stenosis combined with the presence of a CTO artery.

METHODS AND RESULTS

Patients will be prospectively recruited who meet the following criteria:Patients presenting with no necrosis of myocardial tissue in the territory of the CTO will be excluded. Recruited patients will be randomized into 2 groups: those undergoing PCI of only the non-CTO artery (non-CTO PCI group), and those undergoing PCI of the non-CTO artery concurrently with the CTO artery (CTO-PCI group). The primary outcome will be the change in cardiac function evaluated via CMR at a 12-month of follow-up appointment, which will be compared to a baseline measurement. Secondary outcomes include occurrence of major cardiac events, CMR-assessed myocardial viability in the CTO-supplied territory, and quality of life assessed by Seattle angina questionnaire, Patient Health Questionnaire 9 and Generalized Anxiety Disorder Scale-7 after 12-month follow-up.

CONCLUSION

The SOS-moral trial will provide data necessary to determine whether to open concurrent CTOs among MVD patients with CMR-detected necrotic myocardial tissue.

Assessment of myocardial viability by cardiac MRI

PURPOSE OF REVIEW

Left ventricular systolic dysfunction because of coronary artery disease is common, and ascertaining which patients will benefit from revascularization can be challenging. Viability testing is an accepted means by which to base this decision, with multiple noninvasive imaging modalities available for this purpose. This review aims to highlight the key role of cardiac magnetic resonance in myocardial viability assessment, with a focus on its unique strengths over other imaging modalities.

RECENT FINDINGS

Transmural extent of hyperenhancement with late gadolinium imaging has been shown to be greater acutely in ST elevation myocardial infarction patients undergoing primary percutaneous coronary intervention and regress at follow-up studies. An explanation for this reported phenomenon and an argument against redefining CMR viability criteria in the acute setting will be offered.

SUMMARY

Although not universally available, cardiac magnetic resonance is an exceptionally powerful and well tolerated imaging modality that should be considered when viability testing will influence patient management. Although observational outcomes data suggest a promising prognostic role for viability, randomized studies in this area are needed.

Echocardiographic assessment of left ventricular function recovery post percutaneous coronary intervention of chronic total occlusions in patients with low and mid-range left ventricular ejection fractions

OBJECTIVES

Coronary chronic total occlusion (CTO) is a frequent condition encountered in cardiac catheterization laboratory with a prevalence of about 20%. Through literature, data are scarcely reported regarding the left ventricular (LV) function recovery post CTO percutaneous coronary intervention (PCI) in patients with low (<40%) and mid-range (40%-49%) LV ejection fraction (LVEF). The aim of this study was to assess the echocardiographic outcomes of CTO patients with low and mid-range LVEF successfully revascularized at 6-month follow-up.

METHODS

This prospective study included 75 patients with at least one CTO of an epicardial coronary artery proved by previous diagnostic coronary angiography with PCI attempt indication, and successfully revascularized. They were equally divided according to LVEF into three groups, and echocardiographic remodeling indices were assessed at baseline and 6 months post PCI.

RESULTS

Our study showed significant improvement of LVEF, S-wave velocity by tissue doppler imaging (TDI), LV wall-motion score (LVWMS), and LV systolic sphericity index (LVSIS) 6 months post CTO PCI in low LVEF group, and a significant improvement in LVEF, S-wave velocity, and LVWMS in mid-range LVEF group (P < .05). The delta change in LVEF was significantly more in low LVEF group, compared to the other two groups (F = 4.739, P < .05).

CONCLUSION

Successful CTO PCI in patients with low and mid-range LVEF is associated with significant improvement of LVEF and other indices of myocardial remodeling after 6 months of follow-up.

Journal of Cardiovascular Magnetic Resonance: 2017/2018 in review

There were 89 articles published in the Journal of Cardiovascular Magnetic Resonance (JCMR) in 2017, including 76 original research papers, 4 reviews, 5 technical notes, 1 guideline, and 3 corrections. The volume was down slightly from 2017 with a corresponding 15% decrease in manuscript submissions from 405 to 346 and thus reflects a slight increase in the acceptance rate from 25 to 26%. The decrease in submissions for the year followed the initiation of the increased author processing charge (APC) for Society for Cardiovascular Magnetic Resonance (SCMR) members for manuscripts submitted after June 30, 2018. The quality of the submissions continues to be high. The 2018 JCMR Impact Factor (which is published in June 2019) was slightly lower at 5.1 (vs. 5.46 for 2017; as published in June 2018. The 2018 impact factor means that on average, each JCMR published in 2016 and 2017 was cited 5.1 times in 2018. Our 5 year impact factor was 5.82.In accordance with Open-Access publishing guidelines of BMC, the JCMR articles are published on-line in a continuus fashion in the chronologic order of acceptance, with no collating of the articles into sections or special thematic issues. For this reason, over the years, the Editors have felt that it is useful for the JCMR audience to annually summarize the publications into broad areas of interest or themes, so that readers can view areas of interest in a single article in relation to each other and contemporaneous JCMR publications. In this publication, the manuscripts are presented in broad themes and set in context with related literature and previously published JCMR papers to guide continuity of thought within the journal. In addition, as in the past two years, I have used this publication to also convey information regarding the editorial process and as a "State of our JCMR."This is the 12th year of JCMR as an open-access publication with BMC (formerly known as Biomed Central). The timing of the JCMR transition to the open access platform was "ahead of the curve" and a tribute to the vision of Dr. Matthias Friedrich, the SCMR Publications Committee Chair and Dr. Dudley Pennell, the JCMR editor-in-chief at the time. The open-access system has dramatically increased the reading and citation of JCMR publications and I hope that you, our authors, will continue to send your very best, high quality manuscripts to JCMR for consideration. It takes a village to run a journal and I thank our very dedicated Associate Editors, Guest Editors, Reviewers for their efforts to ensure that the review process occurs in a timely and responsible manner. These efforts have allowed the JCMR to continue as the premier journal of our field. This entire process would also not be possible without the dedication and efforts of our managing editor, Diana Gethers. Finally, I thank you for entrusting me with the editorship of the JCMR as I begin my 4th year as your editor-in-chief. It has been a tremendous experience for me and the opportunity to review manuscripts that reflect the best in our field remains a great joy and highlight of my week!

Exercise testing after chronic total coronary occlusion revascularization in patients with STEMI and a concurrent CTO: A subanalysis of the EXPLORE-trial

OBJECTIVES

To assess the effect of chronic total occlusion percutaneous coronary intervention (CTO PCI) on ventricular ectopy (VE) and symptomatology during exercise testing.

BACKGROUND

During exercise, the hypoxic myocardium in the CTO-territory can act as a substrate for VE and could lead to anginal complaints.

METHODS

In the EXPLORE-trial, 302 ST-segment elevation myocardial infarction (STEMI)-patients were randomized to CTO PCI or no-CTO PCI. For this sub-study, we analyzed all available exercise electrocardiograms (X-ECGs) at 4 months follow-up on symptoms and electrocardiographic parameters.

RESULTS

A total of 155 X-ECGs were available, 80 in the CTO PCI group (51.6%) and 75 in the no-CTO PCI group (48.4%). There were no differences regarding exercised time, achieved endurance, ST-deviation nor maximum heart-rate. The percentage of patients experiencing chest-pain during exercise was lower in the CTO PCI group (0% vs. 8.5%, p = .03). Also, there was a trend towards a higher maximum systolic blood pressure (SBP, 185 mmHg vs. 175, p = .09). No difference in VE was found between randomization groups, but patients with successful CTO PCI had a higher frequency of VE, compared to failed and no-CTO PCI (26% vs. 8%, p = .02). This did not result in higher frequencies of sustained ventricular arrhythmias or mortality.

CONCLUSION

In conclusion, in STEMI-patients, CTO PCI is associated with a small reduction of chest-pain during exercise and tended to be associated with an increase of maximum SBP. The observation that successful CTO PCI was associated with more VE during exercise, compared with failed/no-CTO PCI needs further exploration.

Recovery and prognostic value of myocardial strain in ST-segment elevation myocardial infarction patients with a concurrent chronic total occlusion

Objectives

Global left ventricular (LV) function is routinely used to assess cardiac function; however, myocardial strain is able to identify more subtle dysfunction. We aimed to determine the recovery and prognostic value of featuring tracking (FT) cardiovascular magnetic resonance (CMR) strain in ST-segment elevation myocardial infarction (STEMI) patients with a concurrent chronic total occlusion (CTO).

Methods

In the randomized EXPLORE trial, there was no significant difference in global LV function after percutaneous coronary intervention (PCI) of the CTO, compared with no-CTO PCI, post-STEMI. In the current study, we included 200 of the 302 EXPLORE patients with a baseline CMR, of which 180 also had 4-month follow-up (serial) CMR. Global longitudinal strain (GLS) was calculated from 3 long-axis views. Global circumferential strain (GCS) and segmental strain were calculated from 3 short-axis views (basal, mid, and apical).

Results

Global strain significantly improved at 4 months (GLS ∆ − 1.8 ± 4.3%, p < 0.001; GCS ∆ − 1.7 ± 4.7%, p < 0.001); however, there was no treatment effect of CTO-PCI on strain recovery. GLS was a significant predictor for 4 months of LV ejection fraction (p = 0.006), incremental to other CMR parameters including infarct size. For mortality, infarct size remained the strongest predictor. On regional level, segmental strain independently predicted recovery in the dysfunctional segments (p < 0.001).

Conclusions

Global and segmental myocardial strains significantly improved over time, with no effect of CTO-PCI. Global strain was associated with outcome and segmental strain was an independent predictor for regional LV recovery in the dysfunctional CTO territory. Further research is needed to determine the additional prognostic value of strain beyond routine CMR parameters.

Key Points

• In STEMI patients with a concurrent CTO, strain significantly improves over time, regardless of CTO-PCI.

• Global strain is an independent predictor for functional recovery, incremental to infarct size, LVEF, and clinical parameters.

• Segmental strain was able to predict the recovery of wall thickening, incremental to transmural extent of infarction.

Electronic supplementary material

The online version of this article (10.1007/s00330-019-06338-x) contains supplementary material, which is available to authorized users.

Surgical Revascularization of Chronically Occluded Coronary Arteries—What You See Is What You Get?

Background Revascularization strategy in coronary artery bypass grafting (CABG) surgery usually depends on coronary dimension and stenosis severity. Little is known about the relation of preoperative evaluation of scarcely or invisibly chronic occluded coronary arteries (chronic total occlusion [CTO]) and revascularization rate or anastomosis quality. We aimed to evaluate the success rates of CTO revascularization in CABG surgery and determine the influence of coronary lumen visibility and collateralization in preoperative angiograms on revascularization rates, bypass blood flow, and target vessel diameter.

Method Preoperative coronary angiograms were evaluated for 938 consecutive patients who underwent isolated CABG surgery between 2014 and 2016 and screened for occluded coronary arteries. The occluded vessels were scored for visibility using the Rentrop grading of collateral filling. Intraoperatively, dimensions of the occluded arteries were measured using conventional vessel probes, and anastomosis quality was assessed by transit time flow measurement.

Results A total of 404 (43.1%) patients were identified with at least one CTO. Revascularization rates differed from 96.2% in the left anterior descending artery, to 85.0% in left circumflex artery-dependent vessels, and 78.8% in right coronary artery territory. Coronary visibility and grade of collateralization in the preoperative angiogram had no influence on intraoperatively measured coronary diameter. Bypass blood flow in grafts revascularizing CTOs lacking collateralization were not significantly lower than those grafts leading to CTOs with higher Rentrop scores.

Conclusion Preoperative coronary assessment often differs from intraoperative findings. Our study confirms that even patients with scarcely collateralized CTOs and impaired visibility in the coronary angiogram have a high chance of complete revascularization during CABG surgery.

Value of the SYNTAX Score in ST-Elevation Myocardial Infarction Patients With a Concomitant Chronic Total Coronary Occlusion(from the EXPLORE Trial)

`To analyze the impact of additional coronary artery disease, quantified by the SYNTAX (SYNergy between PCI with TAXus and cardiac surgery) score, on left ventricular ejection fraction (LVEF) and long-term outcomes in a cohort of ST-elevated myocardial infarction (STEMI) patients with a concomitant chronic total coronary occlusion (CTO). A total of 302 STEMI patients were randomized to percutaneous coronary intervention of a CTO (CTO PCI) (n = 148) or conservative CTO treatment (n = 154). SYNTAX scores were calculated by an independent corelab (Cardialysis BV, Rotterdam) at two time-points: (1) at baseline, and (2) after primary PCI in the conservative CTO arm and after CTO PCI in the invasive arm (named 'discharge SYNTAX score'). The population was divided in two groups (below or equal to the median SYNTAX score preprimary PCI, or above the median). At 4-month follow-up, the LVEF was significantly lower in patients in the group with a SYNTAX score above the group median (42.8% vs 48.5%, p = 0.001), and the SYNTAX score was an independent predictor for LVEF at 4 months (β-0.151 (SE 0.068), p = 0.028). In the group with a SYNTAX score above the group median the mortality rate was higher (10.1% vs 3.9%, p = 0.025), and there was a trend towards a higher MACE rate (15.4% vs 8.5%, p = 0.063). In conclusion, in this sub-analysis of the EXPLORE trial we observed a worse LVEF and a higher mortality rate for patients with a SYNTAX score above the median. We found that the SYNTAX score is an independent negative predictor for LVEF and an independent positive predictor for LVEDV at 4-month follow-up.

Current Evidence and Rationale of Percutaneous Therapy for Chronic Total Coronary Occlusions

The prevalence of chronic total occlusion (CTO) lesions in coronary arteries is notably high in patients with significant coronary artery disease. However, only a relatively small fraction of observed CTOs classically go for revascularization. Recent advances in techniques and equipment has greatly improved the success rates of CTO revascularization while reducing complications. There has also been an increasing body of evidence regarding clinical benefit of CTO revascularization. However, until recently majority of the evidence was observational and based on data from large multicenter registries. Recent randomized studies have reported on clinical benefits of CTO revascularization particularly with relief of angina. However, there is heterogeneity of results among different studies and the magnitude of benefit is not consistently seen in all studies. This article reviews the existing literature on the current evidence regarding clinical benefits and other rationale for CTO revascularization.

Journal of Cardiovascular Magnetic Resonance 2017

There were 106 articles published in the Journal of Cardiovascular Magnetic Resonance (JCMR) in 2017, including 92 original research papers, 3 reviews, 9 technical notes, and 1 Position paper, 1 erratum and 1 correction. The volume was similar to 2016 despite an increase in manuscript submissions to 405 and thus reflects a slight decrease in the acceptance rate to 26.7%. The quality of the submissions continues to be high. The 2017 JCMR Impact Factor (which is published in June 2018) was minimally lower at 5.46 (vs. 5.71 for 2016; as published in June 2017), which is the second highest impact factor ever recorded for JCMR. The 2017 impact factor means that an average, each JCMR paper that were published in 2015 and 2016 was cited 5.46 times in 2017.In accordance with Open-Access publishing of Biomed Central, the JCMR articles are published on-line in continuus fashion and in the chronologic order of acceptance, with no collating of the articles into sections or special thematic issues. For this reason, over the years, the Editors have felt that it is useful to annually summarize the publications into broad areas of interest or theme, so that readers can view areas of interest in a single article in relation to each other and other contemporary JCMR articles. In this publication, the manuscripts are presented in broad themes and set in context with related literature and previously published JCMR papers to guide continuity of thought within the journal. In addition, I have elected to use this format to convey information regarding the editorial process to the readership.I hope that you find the open-access system increases wider reading and citation of your papers, and that you will continue to send your very best, high quality manuscripts to JCMR for consideration. I thank our very dedicated Associate Editors, Guest Editors, and Reviewers for their efforts to ensure that the review process occurs in a timely and responsible manner and that the JCMR continues to be recognized as the forefront journal of our field. And finally, I thank you for entrusting me with the editorship of the JCMR as I begin my 3rd year as your editor-in-chief. It has been a tremendous learning experience for me and the opportunity to review manuscripts that reflect the best in our field remains a great joy and highlight of my week!

The effect of revascularization of a chronic total coronary occlusion on electrocardiographic variables. A sub-study of the EXPLORE trial

INTRODUCTION

Chronic total coronary occlusions (CTOs) have been associated with a higher prevalence of ventricular arrhythmias compared to patients without a CTO. We evaluated the effect of CTO revascularization on electrocardiographic (ECG) variables.

METHODS

We studied a selection of ST-elevation myocardial infarction patients with a concomitant CTO enrolled in the EXPLORE trial. ECG variables and cardiac function were analysed at baseline and at 4 months follow-up.

RESULTS

Patients were randomized to percutaneous coronary intervention (PCI) of their CTO (n = 77) or to no-CTO PCI (n = 81). At follow-up, median QT dispersion was significantly lower in the CTO PCI group compared to the no-CTO PCI group (46 ms [33-58] vs. 54 ms [37-68], P = 0.043). No independent association was observed between ECG variables and cardiac function.

CONCLUSION

Revascularization of a CTO after STEMI significantly shortened QT dispersion at 4 months follow-up. These findings support the hypothesis that CTO revascularization reduces the pro-arrhythmic substrate in CTO patients.

Impact of collateralisation to a concomitant chronic total occlusion in patients with ST-elevation myocardial infarction: a subanalysis of the EXPLORE randomised controlled trial

Objective

The impact on cardiac function of collaterals towards a concomitant chronic total coronary occlusion (CTO) in patients with ST-elevation myocardial infarction (STEMI) has not been investigated yet. Therefore, we have evaluated the impact of well-developed collaterals compared with poorly developed collaterals to a concomitant CTO in STEMI.

Methods and results

In the EXPLORE trial, patients with STEMI and a concomitant CTO were randomised to either CTO percutaneous coronary intervention (PCI) or no-CTO PCI. Collateral grades were scored angiographically using the Rentrop grade classification. Left ventricular ejection fraction (LVEF) and left ventricular end-diastolic volume (LVEDV) at 4 months were measured using cardiac magnetic resonance imaging. Well-developed collaterals (Rentrop grades 2-3) to the CTO were present in 162 (54%) patients; these patients had a significantly higher LVEF at 4 months (46.2±11.4% vs 42.1±12.7%, p=0.004) as well as a trend for a lower LVEDV (208.2±55.7 mL vs 222.6±68.5 mL, p=0.054) when compared with patients with poorly developed collaterals to the CTO. There was no significant difference in the total amount of scar in the two groups. Event rates were statistically comparable between patients with well-developed collaterals and poorly developed collaterals to the CTO at long-term follow-up.

Conclusions

In patients with STEMI and a concomitant CTO, the presence of well-developed collaterals to a concomitant CTO is associated with a better LVEF at 4 months. However, this effect on LVEF did not translate into improvement in clinical outcome. Therefore, the presence of well-developed collaterals is important, but should not solely guide in the clinical decision-making process regarding any additional revascularisation of a concomitant CTO in patients with STEMI.

Clinical trial registration

NTR1108.

Diagnostic accuracy of multi-slice computed tomography in identifying lesion characteristics in coronary total occlusion

We performed this study to compare the sensitivity and specificity of multi-slice computed tomography (MSCT) to coronary angiography (CA) in detecting coronary total occlusion (CTO) lesion characteristics. Moreover, we analyzed the association between these characteristics and the risk of revascularization failure. Fifty patients with confirmed CTO diagnosis were tried for revascularization using the antegrade (all 50) or retrograde (in failed nine antegrade interventions) approaches. Each patient underwent CA and MSCT before the intervention and data from both modalities were compared using the SPSS software. Successful revascularization occurred in 36 (72%) and 6 (66.7%) patients of the antegrade and retrograde groups, respectively. Compared to CA, MSCT exhibited high sensitivity in detecting CTO segment calcification (100%), size of the affected vessel (100%, area under the curve [AUC] = 0.82), distal filling of the affected segment (97.7%) and side-branching at the CTO segment (93.3%). However, it had lower sensitivity in detecting collaterals (75%) and the length of the affected segment (87.5%, AUC = 0.77). According to MSCT data, increased occlusion length > 18 mm (p = 0.01), atherosclerotic vessel wall (p = 0.02), small distal vessel size ≤ 2.75 mm (p = 0.002), proximal side-branching (p = 0.01) and calcification of the proximal cap (p = 0.007) or distal stump (p = 0.01) were associated with an increased risk of revascularization failure. MSCT exhibited high sensitivity in identifying several CTO lesion characteristics, such as lesional calcification and size of the affected vessel. However, further research is needed to improve the diagnostic accuracy of this modality and define the predictors of revascularization failure in CTO patients.

Evaluation of the Impact of a Chronic Total Coronary Occlusion on Ventricular Arrhythmias and Long-Term Mortality in Patients With Ischemic Cardiomyopathy and an Implantable Cardioverter-Defibrillator (the eCTOpy-in-ICD Study)

Background

Previous studies report conflicting results about a higher incidence of ventricular arrhythmias in patients with a chronic total coronary occlusion (CTO). We aimed to investigate this association in a large cohort of implantable cardioverter defibrillator patients with long‐term follow‐up.

Methods and Results

All consecutive patients from 1992 onwards who underwent implantable cardioverter defibrillator implantation for ischemic cardiomyopathy at the Leiden University Medical Center were evaluated. Coronary angiograms were reviewed for the presence of a CTO. The occurrence of ventricular arrhythmias and survival status at follow‐up were compared between patients with and patients without a CTO. A total of 722 patients constitute the study cohort (age 66±11 years; 84% males; 74% primary prevention, median left ventricular ejection fraction 30% [first–third quartile: 25–37], 44% received a cardiac resynchronization therapy defibrillator). At baseline, 240 patients (33%) had a CTO, and the CTOs were present for at least 44 (2–127) months. The median follow‐up duration was 4 (2–6) years. On long‐term follow‐up, CTO patients had a higher crude appropriate device therapy rate (37% versus 27%, P=0.010) and a lower crude survival rate (51% versus 67%, P<0.001) compared with patients without a CTO. Corrected for baseline characteristics including left ventricular ejection fraction, the presence of a CTO was an independent predictor for appropriate device therapy.

Conclusions

The presence of a CTO in implantable cardioverter defibrillator patients was associated with more appropriate device therapy and worse prognosis at long‐term follow‐up. Further investigation is warranted regarding a potential beneficial effect of CTO revascularization on the incidence of ventricular arrhythmias.

Staged Percutaneous Intervention for Concurrent Chronic Total Occlusions in Patients With ST-Segment-Elevation Myocardial Infarction: A Systematic Review and Meta-Analysis

Background

Studies have shown that chronic total occlusion (CTO) in a noninfarct‐related artery in patients with ST‐segment–elevation myocardial infarction is linked to increased mortality. It remains unclear whether staged revascularization of a noninfarct‐related artery CTO in patients with ST‐segment–elevation myocardial infarction translates to improved outcomes. We performed a meta‐analysis to compare outcomes between patients presenting with ST‐segment–elevation myocardial infarction with concurrent CTO who underwent percutaneous coronary intervention of noninfarct‐related artery CTO versus those who did not.

Method and Results

We conducted an electronic database search of all published data. The primary end point was major adverse cardiovascular events. Secondary end points were all‐cause mortality, cardiovascular mortality, myocardial infarction, repeat revascularization with either percutaneous coronary intervention or coronary artery bypass grafting, stroke, and heart failure readmission. Odds ratios (ORs) and 95% confidence intervals (CIs) were computed. Random effects model was used and heterogeneity was considered if I² >25. Six studies (n=1253 patients) were included in the analysis. There was a significant difference in major adverse cardiovascular events (OR, 0.54; 95% CI, 0.32–0.91), cardiovascular mortality (OR, 0.43; 95% CI, 0.20–0.95), and heart failure readmissions (OR, 0.57; 95% CI, 0.36–0.89), favoring the patients in the CTO percutaneous coronary intervention group. No significant differences were observed between the 2 groups for all‐cause mortality (OR, 0.47; 95% CI, 0.22–1.00), myocardial infarction (OR, 0.78; 95% CI, 0.41–1.46), repeat revascularization (OR, 1.13; 95% CI, 0.56–2.27), and stroke (OR, 0.51; 95% CI, 0.20–1.33).

Conclusions

In this meta‐analysis, CTO percutaneous coronary intervention of the noninfarct‐related artery in patients presenting with ST‐segment–elevation myocardial infarction was associated with a significant reduction in major adverse cardiovascular events, cardiovascular mortality, and heart failure readmissions.

Long-term impact of chronic total occlusion recanalisation in patients with ST-elevation myocardial infarction

Background

During primary percutaneous coronary intervention (PCI), a concurrent chronic total occlusion (CTO) is found in 10% of patients with ST-elevation myocardial infarction (STEMI). Long-term benefits of CTO-PCI have been suggested; however, randomised data are lacking. Our aim was to determine mid-term and long-term clinical outcome of CTO-PCI versus CTO-No PCI in patients with STEMI with a concurrent CTO.

Methods

The Evaluating Xience and left ventricular function in PCI on occlusiOns afteR STEMI (EXPLORE) was a multicentre randomised trial that included 302 patients with STEMI after successful primary PCI with a concurrent CTO. Patients were randomised to either CTO-PCI or CTO-No PCI. The primary end point of the current study was occurrence of major adverse cardiac events (MACE): cardiac death, coronary artery bypass grafting and MI. Other end points were 1-year left ventricular function (LVF); LV-ejection fraction and LV end-diastolic volume and angina status.

Results

The median long-term follow-up was 3.9 (2.1–5.0) years. MACE was not significantly different between both arms (13.5% vs 12.3%, HR 1.03, 95% CI 0.54 to 1.98; P=0.93). Cardiac death was more frequent in the CTO-PCI arm (6.0% vs 1.0%, P=0.02) with no difference in all-cause mortality (12.9% vs 6.2%, HR 2.07, 95% CI 0.84 to 5.14; P=0.11). One-year LVF did not differ between both arms. However, there were more patients with freedom of angina in the CTO-PCI arm at 1 year (94% vs 87%, P=0.03).

Conclusions

In this randomised trial involving patients with STEMI with a concurrent CTO, CTO-PCI was not associated with a reduction in long-term MACE compared to CTO-No PCI. One-year LVF was comparable between both treatment arms. The finding that there were more patients with freedom of angina after CTO-PCI at 1-year follow-up needs further investigation.

Clinical trial registration

EXPLORE trial number NTR1108 www.trialregister.nl.

Angiographic predictors of success in antegrade approach of Chronic Total Occlusion interventions in a South Indian population in the contemporary era

Chronic Total Occlusion (CTO) intervention is a challenging area in interventional cardiology. Presently about 70% of CTO interventions are successful.

MATERIALS AND METHODS

This was a single center prospective study of a cohort of all patients undergoing percutaneous coronary intervention (PCI) as elective or adhoc procedure for CTO from August 2014 to June 2015. Only antegrade CTO interventions were included. In all patients the following data were recorded.

RESULTS

A total of 210 (8.9% of total PCI (2353) during the study period) CTO patients were followed up. The mean age was 56.54±8.9. In the study sixty nine patients (32.9%) presented with chronic stable angina and rest of the patients had history of acute coronary syndrome of which 22.9% (n=48) had unstable angina (UA) or non ST elevation myocardial infarction (NSTEMI) and 44.2% (n=93) had ST Elevation Myocardial Infarction (STEMI). In those with history of ACS, 64.78% (n=92) had ACS during the previous year and remaining 35.22% (n=49) had ACS prior to that. Single vessel CTO was seen in 89.5% (n=188) and two vessel CTO in 10.5% (n=22). LAD was involved in 36.7% (n=77), RCA in 48.1% (n=101), and LCX in 15.2% (n=32). Procedural success in the first attempt was 68.1% (n=143), which increased to 71.42% (n=150) after the second attempt. CTO interventions were more frequently successful when the calcium was absent or minimal (p-0.05), CTO length was <10mm (p<0.01) and good distal reformation (p<0.01).