The myocardium supplied by a chronic total occlusion is a persistently ischemic zone

Circulating Progenitor Cells and Coronary Collaterals in Chronic Total Occlusion

BACKGROUND

The role of circulating progenitor cells (CPC) in collateral formation that occurs in the presence of chronic total occlusions (CTO) of a coronary artery is not well established. In stable patients with a CTO, we investigated whether CPC levels are associated with (a) collateral development and (b) ischemic burden, as measured by circulating high sensitivity troponin-I (hsTn-I) levels.

METHODS

CPCs were enumerated by flow cytometry as CD45med+ blood mononuclear cells expressing CD34 and both CD34 and CD133 epitopes. The association between CPC counts and both Rentrop collateral grade (0, 1, 2, or 3) and hsTn-I levels were evaluated using multivariate regression analysis, after adjusting for demographic and clinical characteristics.

RESULTS

In 89 patients (age 65.5, 72% male, 27% Black), a higher CPC count was positively associated with a higher Rentrop collateral grade; [CD34+ adjusted odds ratio (OR) 1.49 95% confidence interval (CI) (0.95, 2.34) P = 0.082] and [CD34+/CD133+ OR 1.57 95% CI (1.05, 2.36) P = 0.028]. Every doubling of CPC counts was also associated with lower hsTn-I levels [CD34+ β -0.35 95% CI (-0.49, -0.15) P = 0.002] and [CD34+/CD133+ β -0.27 95% CI (-0.43, -0.08) P = 0.009] after adjustment.

CONCLUSION

Individuals with higher CPC counts have greater collateral development and lower ischemic burden in the presence of a CTO.

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.

Incidence of ventricular arrhythmias in patients with chronic total coronary occlusion: Results of the VACTOR study

Background

A chronic total coronary occlusion (CTO) is associated with ventricular arrhythmias (VA) in patients with an implantable cardioverter-defibrillator (ICD). Limited data is available on the incidence of VA in CTO patients without an ICD.

Objectives

To investigate the incidence of sustained VA in CTO patients after successful CTO revascularization and in patients with untreated CTO or failed CTO revascularization.

Methods

Prospective, multicenter observational pilot study including CTO patients who were not eligible for an ICD and had a left ventricular ejection fraction >35 %. We enrolled patients with a successful CTO revascularization (group A) and patients with untreated CTO or failed CTO revascularization (group B). All patients received an implantable loop recorder with remote monitoring. The primary endpoint was sustained VA.

Results

Ninety patients were enrolled (mean age 63 ± 10 years, 83.3 % man, mean LVEF 55 ± 8 %). Group A (n = 45) had a higher prevalence of CTO in the left anterior descending artery in comparison to group B (n = 45) (28.9 % versus 4.4 %, P = 0.002). Other baseline characteristics were similar. During a median follow-up time of 26 months (IQR, 19-35), five patients (5.6 %) had a sustained VA. There was no difference in the incidence of sustained VA between groups (3-year cumulative event rate: 8.8 % (group A) versus 4.5 % (Group B), log-rank P = 0.71).

Conclusion

Patients with an CTO, who do not qualify for an ICD, have a substantial risk of sustained VA. In our study the incidence was not different between patients with revascularized and those with untreated CTO.

High Sensitivity Troponin Level and Benefits of Chronic Total Occlusion Revascularization

Background The survival benefit of revascularization of chronic total occlusion (CTO) of the coronary arteries remains a subject of controversy. We measured high sensitivity troponin-I (hsTn-I) levels as an estimate of myocardial ischemia in patients with stable coronary artery disease, with the hypothesis that (1) patients with CTO have higher levels of hsTn-I than patients without CTO, (2) hsTn-I levels will predict adverse cardiovascular events in patients with CTO, and (3) patients with elevated hsTn-I levels will have a survival benefit from CTO revascularization. Methods and Results In 428 patients with stable coronary artery disease and CTO undergoing coronary angiography, adverse event rates were investigated. Cox proportional hazards models and Fine and Gray subdistribution hazard models were performed to determine the association between hsTn-I level and incident event rates in patients with CTO. HsTn-I levels were higher in patients with compared with those without CTO (median 6.7 versus 5.6 ng/L, P=0.002). An elevated hsTn-I level was associated with higher adverse event rates (adjusted all-cause mortality hazard ratio, 1.19 [95% CI, 1.08-1.32]; P=0.030) for every doubling of hsTn-I level. CTO revascularization was performed in 28.3% of patients. In patients with a high (>median) hsTn-I level, CTO revascularization was associated with substantially lower all-cause mortality (adjusted hazard ratio, 0.26 [95% CI, 0.08-0.88]; P=0.030) compared with those who did not undergo revascularization. In patients with a low ( Collapse

Key Words

• chronic total occlusion
• coronary artery bypass graft
• high sensitivity troponin‐I
• percutaneous coronary intervention

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MESH Headings

• Humans
• Coronary Artery Disease/complications
• Coronary Occlusion
• Risk Factors
• Treatment Outcome
• Percutaneous Coronary Intervention/adverse effects
• Coronary Angiography/adverse effects
• Chronic Disease
• Troponin I

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Grants

• U54 AG062334 NIA NIH HHS
• P01 HL154996 NHLBI NIH HHS
• R33 HL138657 NHLBI NIH HHS
• P01 HL086773 NHLBI NIH HHS
• P30 DK111024 NIDDK NIH HHS
• R01 HL109413 NHLBI NIH HHS
• R01 HL166004 NHLBI NIH HHS
• R61 HL154116 NHLBI NIH HHS
• P20 HL113451 NHLBI NIH HHS
• P01 HL101398 NHLBI NIH HHS

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Affiliation(s)

Daniel A. Gold Division of Cardiology, Department of MedicineEmory Clinical Cardiovascular Research Institute, Emory University School of MedicineAtlantaGA
Pratik B. Sandesara Division of Cardiology, Department of MedicineEmory Clinical Cardiovascular Research Institute, Emory University School of MedicineAtlantaGA
Vardhmaan Jain Division of Cardiology, Department of MedicineEmory Clinical Cardiovascular Research Institute, Emory University School of MedicineAtlantaGA
Matthew E. Gold Division of Cardiology, Department of MedicineEmory Clinical Cardiovascular Research Institute, Emory University School of MedicineAtlantaGA
Nishant Vatsa Division of Cardiology, Department of MedicineEmory Clinical Cardiovascular Research Institute, Emory University School of MedicineAtlantaGA
Shivang R. Desai Division of Cardiology, Department of MedicineEmory Clinical Cardiovascular Research Institute, Emory University School of MedicineAtlantaGA
Malika Elhage Hassan Division of Cardiology, Department of MedicineEmory Clinical Cardiovascular Research Institute, Emory University School of MedicineAtlantaGA
Chenyang Yuan Department of Biostatistics and Bioinformatics, Rollins School of Public HealthEmory UniversityAtlantaGA
Yi‐An Ko Department of Biostatistics and Bioinformatics, Rollins School of Public HealthEmory UniversityAtlantaGA
Ayman Alkhoder Division of Cardiology, Department of MedicineEmory Clinical Cardiovascular Research Institute, Emory University School of MedicineAtlantaGA
Kiran Ejaz Division of Cardiology, Department of MedicineEmory Clinical Cardiovascular Research Institute, Emory University School of MedicineAtlantaGA
Zain Alvi Division of Cardiology, Department of MedicineEmory Clinical Cardiovascular Research Institute, Emory University School of MedicineAtlantaGA
Alireza Rahbar Division of Cardiology, Department of MedicineEmory Clinical Cardiovascular Research Institute, Emory University School of MedicineAtlantaGA
Gillian Murtagh Abbott Diagnostics, Abbott LaboratoriesAbbott ParkIL
Wissam A. Jaber Division of Cardiology, Department of MedicineEmory Clinical Cardiovascular Research Institute, Emory University School of MedicineAtlantaGA
William J. Nicholson Division of Cardiology, Department of MedicineEmory Clinical Cardiovascular Research Institute, Emory University School of MedicineAtlantaGA
Arshed A. Quyyumi Division of Cardiology, Department of MedicineEmory Clinical Cardiovascular Research Institute, Emory University School of MedicineAtlantaGA

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Non-revascularized chronic total occlusions impact on substrate and post-ablation results in drug-refractory electrical storm

Background and aims

There is limited data concerning the effect of non-revascularized chronic total occlusions (NR-CTOs) after VT ablation. This study sought to evaluate the impact of NR-CTOs after ablation for electrical storm (ES).

Methods

Post-hoc retrospective analysis of data regarding 64 consecutive post-myocardial infarction patients (out of which 12 patients with NR-CTOs and 52 without NR-CTOs) undergoing substrate ablation for ES with an available median follow-up of 37.53 (7.25-64.65) months. Ablation result was assessed by inducibility of sustained monomorphic VT (SMVT) during final programmed ventricular stimulation (PVS). The primary endpoints were all-cause mortality and VT/VF recurrences after ablation, respectively, stratified by the presence of NR-CTOs. The secondary endpoint was to assess the predictive effect of NR-CTOs on all-cause mortality and VT/VF recurrences in relation to other relevant prognostic factors.

Results

At baseline, the presence of NR-CTOs was associated with higher bipolar BZ-to-total scar ratio (72.4% ± 17.9% vs. 52% ± 37.7%, p = 0.022) and more failure to eliminate the clinical VT (25% (3) vs. 0% (0), p < 0.001). During follow-up, overall all-cause mortality and recurrences were more frequent in the NR-CTO subgroup (75% (9) vs. 19.2% (10), log rank p = 0.003 and 58.3% vs. 23.1% (12), log rank p = 0.042 respectively). After adjusting for end-procedural residual SMVT inducibility, NR-CTOs predicted death during follow-up (HR 3.380, p = 0.009) however not recurrence (HR 1.986, p = 0.154).

Conclusions

NR-CTO patients treated by RFCA for drug-refractory ES demonstrated a higher ratio of BZ-to-total-scar area. In this analysis, NR-CTO was associated with worse acute procedural results and may as well impact long-term outcomes which should be further assessed in larger patient populations.

The Utility of CT Coronary Angiography in Chronic Total Occlusion Percutaneous Coronary Intervention

Chronic total occlusion (CTO) of the coronary arteries is a relatively common finding in routine coronary angiography. Of late, there has been considerable improvement in the success rate of percutaneous intervention for coronary CTO, attributed to technological advancement and skills development. CT coronary angiogram (CTCA) is a simple, non-invasive, and cost-effective test that aids in the diagnosis and management of coronary artery disease, including CTOs. The development of multi-slice CT and the use of 3D volume rendering images has revolutionised the diagnostic abilities of CTCA, with improvements in imaging quality and detailed anatomical and morphological characterisation of the plaque disease. In CTO percutaneous intervention, CTCA is used in pre-procedural planning, applying scoring systems to predict the likely success of the intervention as well as the post-procedural evaluation and follow-up. This review examines the different uses of CTCA in CTO intervention, its impact on successful recanalisation and the areas for future consideration.

Improvement of angiographic and clinical outcomes of percutaneous coronary intervention for chronic total occlusion after implementation of a dedicated team: a single-centre experience

INTRODUCTION

In a Dutch heart centre, a dedicated chronic total occlusion (CTO) team was implemented in June 2017. The aim of this study was to the evaluate treatment success and clinical outcomes before and after this implementation.

METHODS

A total of 662 patients who underwent percutaneous coronary intervention (PCI) for a CTO between January 2013 and June 2020 were included and divided into pre- and post-CTO team groups. The primary endpoint was the angiographic success rate of CTO-PCI. Secondary endpoints included angiographic success stratified by complexity using the J‑CTO score and the following clinical outcomes: in-hospital complications and myocardial infarction, target vessel revascularisation, all-cause mortality, quality of life (QoL) and major adverse cardiac events (MACE) at 30-day and 1‑year follow-up.

RESULTS

Compared with the pre-CTO team group, the success rate in the post-CTO team group was higher after the first attempt (81.4% vs 62.7%; p < 0.001) and final attempt (86.7% vs 73.8%; p = 0.001). This was mainly driven by higher success rates for difficult and very difficult CTO lesions according to the J‑CTO score. The MACE rate at 1 year was lower in the post-CTO team group than in the pre-CTO team group (6.4% vs 16.0%; p < 0.01), while it was comparable at 30-day follow-up (0.1% vs 1.7%; p = 0.74). Angina symptoms were significantly reduced at 30-day and 1‑year follow-up, and QoL scores were higher after 1 year.

CONCLUSION

This study demonstrated higher success rates of CTO-PCI and improved clinical outcomes and QoL at 1‑year follow-up after implementation of a dedicated CTO team using the hybrid algorithm.

Evaluation of right atrial function by two-dimensional echocardiography and strain imaging in patients with RCA CTO recanalization

OBJECTIVES

The right heart is mainly supplied with blood by the right coronary artery (RCA). The impact of RCA chronic total occlusion (CTO) on the function of the right heart [right atrium (RA) and ventricle (RV)] and whether successful recanalization of a RCA CTO improves the function of the right heart is not clearly understood yet. We aimed to evaluate right atrial function after recanalization of the RCA using transthoracic echocardiography with additional strain imaging.

METHODS AND RESULTS

Fifty-five patients undergoing RCA CTO recanalization at the University Medical Center of Mainz were included in the study. Right atrial strain was assessed before and 6 months after successful CTO revascularization. The median age of the total collective was 66 (50-90) years. We did not find difference in our analysis of RA Volume (p 0.086), RA area (p 0.093), RA major dimension (p 0.32) and RA minor dimension (p 0.139) at baseline and follow-up. Mean RA reservoir strain at baseline was 30.9% (21.1-43.0) vs. 33.4% (20.7-47.7) at follow up (p < 0.001). Mean RA conduit strain was - 17.5% (- 10.7-(- 29.7)) at baseline vs. - 18.2% (- 9.6-(- 31.7)) at follow-up (p = 0.346). Mean RA contraction strain was - 12.9% (- 8.0- (- 21.3)) at baseline vs. - 15.5% (- 8.7-(- 26.6)) at follow-up (p < 0.001).

CONCLUSION

Right atrial function was altered in patients with RCA CTO. Successful revascularisation of an RCA CTO improved RA function assessed by strain imaging at follow-up.

Patient Selection and Clinical Indication for Chronic Total Occlusion Revascularization-A Workflow Focusing on Non-Invasive Cardiac Imaging

Percutaneous coronary intervention of chronic total occlusion (CTO PCI) is a challenging procedure with high complication rates and, as not yet fully understood long-term clinical benefits. Ischemic symptom relief in patients with high ischemic burden is to date the only established clinical indication to undergo CTO PCI, supported by randomized controlled trials. In this context, current guidelines suggest attempting CTO PCI only in non-invasively assessed viable CTO correspondent myocardial territories, with large ischemic areas. Hence, besides a comprehensive coronary angiography lesion evaluation, the information derived from non-invasive cardiac imaging techniques is crucial to selecting candidates who may benefit from the revascularization of the occluded vessel. Currently, there are no clear recommendations for a non-invasive myocardial evaluation or choice of imaging modality pre-CTO PCI. Therefore, selecting among available options is left to the physician's discretion. As CTO PCI is strongly recommended to be carried out explicitly in experienced centers, full access to non-invasive imaging for risk-benefit assessment as well as a systematic institutional evaluation process has to be encouraged. In this framework, we opted to review the current myocardial imaging tools and their use for indicating a CTO PCI. Furthermore, based on our experience, we propose a cost-effective systematic approach for myocardial assessment to help guide clinical decision-making for patients presenting with chronic total occlusions.

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.

Impact of chronic total occlusions on outcomes of patients with acute myocardial infarction undergoing percutaneous coronary intervention: A propensity-score matched analysis using the National Inpatient Sample database

BACKGROUND

There is limited data on the impact of chronic total occlusions (CTOs) on the outcomes of patients presenting with acute myocardial infarction (AMI) undergoing percutaneous coronary intervention (PCI) in the contemporary era.

METHODS

We queried the National Inpatient Sample between October 2015 and December 2017 using the International Classification of Diseases, Tenth revision codes to identify hospitalized AMI patients undergoing PCI. A 1:1 propensity-score matched analysis was performed to compare in-hospital outcomes of patients with and without CTOs.

RESULTS

Among 576,760 admissions identified during the study period, 51,225(8.8 %) had CTO and 525,535 (91.1 %) did not. After 1:1 propensity-score matching, each matched group contained 51,210 admissions. In-hospital mortality was significantly higher in the CTO group compared with the non-CTO group (4.7 % vs 3 %, p < 0.0001). In the CTO group, hospital length of stay was longer (median 3 vs 2 days, p = 0.001) and lower percentage of patients were discharged to home (78.8 % vs 81.1 %, p < 0.0001), compared with the non-CTO group. Median cost of hospital stay was also higher in the CTO group compared with the non-CTO group ($20,921 vs $19,856, p < 0.0001).

CONCLUSIONS

In this propensity-score matched analysis of a large US inpatient database, the presence of CTOs in AMI patients undergoing PCI identified a higher risk cohort with in higher in-hospital mortality, longer hospital length of stay and higher hospitalization cost.

Integrated Analysis of Angiogenesis Related lncRNA-miRNA-mRNA in Patients With Coronary Chronic Total Occlusion Disease

Background: Coronary chronic total occlusion (CTO) disease is common and its specific characteristic is collateral formation. The Integrated analysis of angiogenesis related lncRNA-miRNA-mRNA network remains unclear and might provide target for future studies.

Methods: A total of five coronary artery disease (control group) and five CTO (CTO group) patients were selected for deep RNA and miRNA sequencing. The expression profiles of lncRNAs, mRNAs circRNA and miRNAs were obtained. Gene Ontology (GO) and Kyoto Encyclopedia of Genes and Genomes (KEGG) pathway enrichment analyses were then performed. The expression of a 14q32 miRNA gene cluster, including miRNA-494, miRNA-495 and miRNA-329, were selected to be determined in another larger patient cohort. Analysis of the lncRNA-miRNA495-mRNA network was constructed to find potential targets for future studies.

Results: A total of 871 lncRNAs, 1,080 mRNAs, 138 circRNAs and 56 miRNAs were determined as differentially expressed (DE) in CTO patients compared with control patients. GO and KEGG analyses revealed that the top terms included MAPK signaling pathway, HIF-1 signaling pathway, EGFR tyrosine kinase inhibitor resistance, embryonic organ development, wound healing, MAPK signaling pathway and JAK-STAT signaling pathway, which are related to angiogenesis. The expression of miRNA-494, miRNA-495 and miRNA-329 were all significantly down-regulated in CTO patients and they were confirmed to be down-regulated in another cohort of 68 patients. Then we divided the CTO patients into two groups according to CC grade (poor CC group, CC = 0 or one; good CC group, CC = 2). MiRNA-494, miRNA-495 and miRNA-329 were found to be down-regulated in good CC group compared with poor CC group. Analysis of the lncRNA-miRNA495-mRNA network showed 3 DE lncRNA sponges (NONHSAG008675, NONHSAG020957 and NONHSAG010989), 4 DE lncRNA targets (NONHSAT079547.2, NONHSAT081776.2, NONHSAT148555.1 and NONHSAT150928.1) and 2 DE mRNA targets (RAD54L2 and ZC3H4) of miRNA495.

Conclusion: This study revealed that the lncRNA-miRNA-mRNA network might play a critical role in angiogenesis in CTO patients.

Predictors of angina resolution after percutaneous coronary intervention in stable coronary artery disease

BACKGROUND

Elective percutaneous coronary intervention (PCI) is performed to relieve symptoms of angina. Identifying patients who will benefit symptomatically after PCI would be clinically advantageous but robust predictors of symptom resolution are ill-defined.

METHODS

Prospective indexing of baseline angina status, clinical, and procedural characteristics were collected over a 5-year period in a regional revascularization registry. At 1-year follow-up, angina resolution was assessed. We performed a stepwise selection algorithm to identify predictors of persistent angina at 1 year.

RESULTS

A total of 777 patients were included in the analysis and the median follow-up was 387 days. Mean age of the cohort was 66.6 years, 23.8% were female and 23.3% had baseline Canadian Cardiovascular Society class 3 or 4 angina. Overall, 13.1% had persistent angina. The only predictor of persistent angina was the presence of a residual chronic total occlusion after PCI with odds ratio of 3.06 (95% confidence interval, 1.81-5.17). Residual stenoses 50-69%, 70-89%, and 90-99% were not associated with residual angina after PCI.

CONCLUSION

Most patients achieved symptom resolution with PCI and optimal medical therapy. A residual chronic total occlusion after PCI was associated with persistent angina. Other degrees of stenoses were not associated with persistent angina.

Collateral Arteriogenesis Involves a Sympathetic Denervation That Is Associated With Abnormal α-Adrenergic Signaling and a Transient Loss of Vascular Tone

Stimulating collateral arteriogenesis is an attractive therapeutic target for peripheral artery disease (PAD). However, the potency of arteriogenesis-stimulation in animal models has not been matched with efficacy in clinical trials. This may be because the presence of enlarged collaterals is not sufficient to relieve symptoms of PAD, suggesting that collateral function is also important. Specifically, collaterals are the primary site of vascular resistance following arterial occlusion, and impaired collateral vasodilation could impact downstream tissue perfusion and limb function. Therefore, we evaluated the effects of arteriogenesis on collateral vascular reactivity. Following femoral artery ligation in the mouse hindlimb, collateral functional vasodilation was impaired at day 7 (17 ± 3 vs. 60 ± 8%) but restored by day 28. This impairment was due to a high resting diameter (73 ± 4 μm at rest vs. 84 ± 3 μm dilated), which does not appear to be a beneficial effect of arteriogenesis because increasing tissue metabolic demand through voluntary exercise decreased resting diameter and restored vascular reactivity at day 7. The high diameter in sedentary animals was not due to sustained NO-dependent vasodilation or defective myogenic constriction, as there were no differences between the enlarged and native collaterals in response to eNOS inhibition with L-NAME or L-type calcium channel inhibition with nifedipine, respectively. Surprisingly, in the context of reduced vascular tone, vasoconstriction in response to the α-adrenergic agonist norepinephrine was enhanced in the enlarged collateral (−62 ± 2 vs. −37 ± 2%) while vasodilation in response to the α-adrenergic antagonist prazosin was reduced (6 ± 4% vs. 22 ± 16%), indicating a lack of α-adrenergic receptor activation by endogenous norepinephrine and suggesting a denervation of the neuroeffector junction. Staining for tyrosine hydroxylase demonstrated sympathetic denervation, with neurons occupying less area and located further from the enlarged collateral at day 7. Inversely, MMP2 presence surrounding the enlarged collateral was greater at day 7, suggesting that denervation may be related to extracellular matrix degradation during arteriogenesis. Further investigation on vascular wall maturation and the functionality of enlarged collaterals holds promise for identifying novel therapeutic targets to enhance arteriogenesis in patients with PAD.

Improved prediction of electrical storm in patients with prior myocardial infarction and implantable cardioverter defibrillator

AIMS

To evaluate predictors of electrical storm (ES), including chronic total occlusion in an infarct-related coronary artery (infarct-related artery CTO, IRACTO), in a cohort of patients with prior myocardial infarction (MI) and implantable cardioverter-defibrillators (ICD).

METHODS

Multicenter observational cohort study including 643 consecutive patients with prior MI and a first ICD implanted between 2005 and 2018 at three tertiary hospitals. All the patients included in the study had undergone a diagnostic coronary angiography before ICD implantation. The variable prior ventricular arrhythmias (VA+) was positive in patients with secondary prevention ICDs and in those with at least one appropriate ICD therapy after primary prevention implantation.

RESULTS

During a median follow-up of 42 months 59 patients (9%) suffered ES. The presence of at least one IRACTO not revascularized (IRACTO-NR) was associated with a significantly higher cumulative incidence of ES (14.5% vs 4.8%, p < 0.001). IRACTO-NR maintained a significant association with ES after adjustment for potential confounders (HR 2.3, p = 0.005) and was an independent predictor of ES together with VA+ and LVEF. The best cut-off of LVEF to predict ES was ≤38%. A risk-prediction model based on IRACTO-NR, VA+ and LVEF≤38% identified three categories of ES risk (low, intermediate and high), with progressively increasing cumulative incidence of ES (2.2%, 9% and 20%).

CONCLUSION

In a cohort of patients with prior MI and ICD, IRACTO-NR is an independent predictor of ES. A new risk-prediction model allowed the identification of three categories of risk, with potentially important clinical implications.

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.

Assessment of late gadolinium enhancement-negative chronic total occlusion by longitudinal strain analysis using cardiac magnetic resonance imaging

BACKGROUND

Strain analysis has become commonly used in clinical practice in various heart diseases.

PURPOSE

To explore whether late gadolinium enhancement (LGE)-negative areas with coronary artery chronic total occlusion (CTO) appear normal when analyzed for longitudinal strain using cardiac magnetic resonance (CMR) imaging.

MATERIAL AND METHODS

A total of 16 patients and 31 healthy controls who underwent 1.5-T MR at our hospital between January 2015 and July 2017 were included in the study. The LGE-CMR of patients with CTO was negative. Left ventricular functional parameters, segmental longitudinal strain/strain rate, and perfusion parameters were measured using CVI42 software.

RESULTS

For myocardial segments supplied by CTO vessels, systolic longitudinal strain rate (SLSR)was significantly lower than that of healthy controls, and diastolic longitudinal strain rate (DLSR) was significantly higher (1.19 1/s vs. 1.02 1/s; P = 0.018). Moreover, longitudinal strain (LS), SLSR, and DLSR did not differ between good and poor collateral circulation. Perfusion index of CTO territory segments was lower than non-CTO territory segments (0.20 vs. 0.22; P = 0.027). No correlation was found between longitudinal strain parameters and perfusion parameters.

CONCLUSION

Although LGE-CMR was negative in patients with CTO, the myocardial SLSR of CTO territory segments was significantly lower than that of healthy controls.

The indications and utility of adjunctive imaging modalities for chronic total occlusion (CTO) intervention

Coronary chronic total occlusions (CTO) are common in patients undergoing coronary angiography, yet the optimal management strategy remains uncertain, with conflicting results from randomized trials. Appropriate patient selection and careful periprocedural planning are imperative for successful patient management. We review the role of adjunctive imaging modalities including myocardial perfusion imaging (MPI), cardiac magnetic resonance imaging (CMR), echocardiography and computed tomography coronary angiography (CTCA) in myocardial ischemic quantification, myocardial viability assessment, as well as procedural planning for CTO revascularization. An appreciation of the value, indications and limitations of these modalities prior to planned intervention are essential for optimal management.

Trends and outcomes of chronic coronary total occlusion-related ventricular tachyarrhythmias

Our study aims to establish trends and frequencies of ventricular tachyarrhythmia (VTA) among patients with chronic coronary total occlusion (CCTO). We identified CCTO hospitalizations with and without VTA using the National Inpatient Sample. A total of 911,579 CCTO-related hospitalizations were identified, with 92,450 (10.1%) encounters associated with VTA. The CCTO-VTA cohort showed higher all-cause mortality (adjusted odds ratio [aOR] = 4.45, P <  0.001), longer hospital stays (6.8 vs 4.6 days; P <  0.001), and higher hospital charges ($117,382 vs $75,419; P <  0.001) compared to the CCTO non-VTA group. Rates and odds of cardiogenic shock (aOR = 4.19), venous thromboembolism (aOR = 2.09), respiratory failure (aOR = 2.85), and requirement of mechanical ventilation (aOR = 4.23) were higher in the CCTO-VTA group (P <  0.001). Over time, there was an increase in VTA (9.2% in 2010 to 12.1% in 2014) and all-cause mortality (7.5% in 2010 to 12.4% in 2014; P <  0.001). Trends in VTA among patients with CCTO increased by 4.8% for undergoing percutaneous coronary intervention and by 2.5% for undergoing both percutaneous coronary intervention and coronary artery bypass grafting (P <  0.001). Occurrence of VTA among CCTO patients is associated with worse outcomes and higher resource utilization.

Non-invasive Imaging in Patients With Chronic Total Occlusions of the Coronary Arteries-What Does the Interventionalist Need for Success?

Chronic total occlusion (CTO) of coronary arteries is a common finding in patients with known or suspected coronary artery disease (CAD). Although tremendous advances have been made in the interventional treatment of CTOs over the past decade, correct patient selection remains an important parameter for achieving optimal results. Non-invasive imaging can make a valuable contribution. Ischemia and viability, two major factors in this regard, can be displayed using echocardiography, single-photon emission tomography, positron emission tomography, computed tomography, and cardiac magnetic resonance imaging. Each has its own strengths and weaknesses. Although most have been studied in patients with CAD in general, there is an increasing number of studies with positive preselectional factors for patients with CTOs. The aim of this review is to provide a structured overview of the current state of pre-interventional imaging for CTOs.

[Technical armamentarium for chronic total occlusion of coronary vessels]

Percutaneous revascularization of chronic total occlusion (CTO) of coronary vessels represents a major challenge for contemporary interventional cardiologists. In the last decade there has been an unprecedented effort towards the standardization of revascularization procedures for CTO of coronary vessels. This endeavour has been possible by virtue of the growing interest of various cardiological societies for this patient group. Along with supportive endovascular technologies and percutaneous devices specifically dedicated to this interventional target, the increasing experience of interventionalists enabled continuously growing success for revascularization of CTO of coronary vessels. This review article highlights the currently available tools as well as technologies, techniques and strategies for the percutaneous recanalization of CTO of coronary vessels.

Ischemic Burden Reduction and Long-Term Clinical Outcomes After Chronic Total Occlusion Percutaneous Coronary Intervention

OBJECTIVES

The authors sought to evaluate the impact of ischemic burden reduction after chronic total occlusion (CTO) percutaneous coronary intervention (PCI) on long-term prognosis and cardiac symptom relief.

BACKGROUND

The clinical benefit of CTO PCI is questioned.

METHODS

In a high-volume CTO PCI center, 212 patients prospectively underwent quantitative [¹⁵O]H₂O positron emission tomography perfusion imaging before and three months after successful CTO PCI between 2013-2019. Perfusion defects (PD) (in segments) and hyperemic myocardial blood flow (hMBF) (in ml · min^-1 · g^-1) allocated to CTO areas were related to prognostic outcomes using unadjusted (Kaplan-Meier curves, log-rank test) and risk-adjusted (multivariable Cox regression) analyses. The prognostic endpoint was a composite of all-cause death and nonfatal myocardial infarction.

RESULTS

After a median [interquartile range] of 2.8 years [1.8 to 4.3 years], event-free survival was superior in patients with ≥3 versus <3 segment PD reduction (p < 0.01; risk-adjusted p = 0.04; hazard ratio [HR]: 0.34 [95% confidence interval (CI): 0.13 to 0.93]) and with hMBF increase above (Δ≥1.11 ml · min^-1 · g^-1) versus below the population median (p < 0.01; risk-adjusted p < 0.01; HR: 0.16 [95% CI: 0.05 to 0.54]) after CTO PCI. Furthermore, event-free survival was superior in patients without versus any residual PD (p < 0.01; risk-adjusted p = 0.02; HR: 0.22 [95% CI: 0.06 to 0.76]) or with a residual hMBF level >2.3 versus ≤2.3 ml · min^-1 · g^-1 (p < 0.01; risk-adjusted p = 0.03; HR: 0.25 [95% CI: 0.07 to 0.91]) at follow-up positron emission tomography. Patients with residual hMBF >2.3 ml · min^-1 · g^-1 were more frequently free of angina and dyspnea on exertion at long-term follow-up (p = 0.04).

CONCLUSIONS

Patients with extensive ischemic burden reduction and no residual ischemia after CTO PCI had lower rates of all-cause death and nonfatal myocardial infarction. Long-term cardiac symptom relief was associated with normalization of hMBF levels after CTO PCI.

Revascularisation of chronic total occlusions and recurrence rate of ventricular arrhythmias

BACKGROUND

The impact of revascularisation of chronic total occlusions (CTO) on the incidence of ventricular arrhythmias (VA) remains to be elucidated.

METHODS

Based on prospectively gathered data, the recurrence rate of VAs following CTO treatment was retrospectively investigated. Patients presenting with VAs as clinical indication for CTO revascularisation were retrospectively selected out of three Belgian CTO registries (i.e. Ziekenhuis Oost-Limburg, UZ Leuven and CHR de la Citadelle). Freedom of VAs was defined as absence of non-sustained or sustained tachycardias (VT), ventricular fibrillations (Vfib) and ventricular extrasystoles (VES; <2500 VES/24 h). Long-term outcome in terms of reoccurrence of VAs was evaluated by reviewing patient records.

RESULTS

Between 2011 and 2019, 912 patients underwent a CTO-PCI across three Belgian centres. In total 43 patients (5%) presented with VAs as clinical indication for CTO revascularisation. Overall follow-up was 723 (391 - 1144) days. Fourteen (33%), 18 (42%), 5 (11%) and 6 (14%) presented with >2500 VES/24 hrs, non-sustained VT, sustained VT and Vfib, respectively. In those patients with a one-year follow-up available (n = 34), overall recurrence rate of VAs was 38% (within VA group: VES: 25%, non-sustained VT: 46%; sustained VT: 25% and Vfib: 60%).

CONCLUSION

Based on this retrospective data analysis, CTO revascularisation, in patients presenting with VAs as the main clinical indication, seems to beneficially impact the incidence of VAs, which ultimately might result in improved patients' outcome.

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.

Both surgical and percutaneous revascularization improve prognosis in patients with a coronary chronic total occlusion (CTO) irrespective of collateral robustness

The impact of surgical or percutaneous coronary revascularization on prognosis in patients with a chronic total occlusion (CTO) remains uncertain. Particularly, whether revascularization of those with robust coronary collaterals improves prognosis is unknown. The objective of this study was to determine the predictors and prognostic impact of revascularization of a CTO, and to determine the clinical impact of robust coronary collaterals. Patients with a CTO diagnosed on coronary angiography between Jul 2010 and Dec 2019 were included in this study. Management strategy of the CTO was defined as percutaneous coronary intervention (PCI), coronary artery bypass grafting (CABG) or medical management. The degree of collateral robustness was determined by the Rentrop grading classification. Demographic, angiographic and clinical outcomes were recorded. A total of 954 patients were included in the study, of which 186 (19.5%) patients underwent CTO PCI, 296 (31.0%) patients underwent CABG and 472 (49.5%) patients underwent medical management of the CTO. 166 patients (17.4%) had Rentrop grade zero or one collaterals, 577 (60.5%) patients had Rentrop grade two and 211 (22.1%) had Rentrop grade three collaterals. The independent predictors of medical management of the CTO were older age, greater stenosis in the donor vessel, an emergent indication for angiography, a non-LAD CTO and female sex. The degree of collateral robustness was not associated with long-term mortality, while patients who were revascularized either through CABG or PCI had a significantly lower mortality compared to medical management alone (p < 0.0001). In patients with a CTO, the presence of robust collaterals is not associated with prognosis, while both surgical and percutaneous revascularization is associated with improved prognosis. Further research into the optimal revascularization strategy for a CTO is required.

Chronic total occlusion percutaneous coronary intervention in everyday clinical practice - an expert opinion of the Association of Cardiovascular Interventions of the Polish Cardiac Society

Coronary chronic total occlusions (CTO) are increasingly encountered during invasive and non-invasive coronary angiography and remain the most challenging lesions for percutaneous revascularization. During recent years success rates and safety outcomes of CTO percutaneous coronary intervention (PCI) have substantially improved, particularly due to the introduction of new techniques and dedicated equipment as well as specialized training programs of CTO operators. Significantly, the steady advances in CTO PCI techniques have coincided with the new data from randomized clinical trials supporting the role of percutaneous recanalization of CTO in relieving angina and improving the quality of life. The current expert consensus document outlines the rationale, clinical outcomes as well as technical, safety and reimbursement issues of CTO PCI. In addition, the requirements for achieving and maintaining competency in CTO PCI among interventional cardiologists are discussed. Finally, we present the modified hybrid algorithm (the so-called Polish hybrid algorithm) providing some unique refinements to the contemporary CTO PCI strategies. Continuous efforts (including active engagement with the payer) are urgently needed to increase guideline-recommended referrals to CTO PCI, and thus improve the quality of life of CTO patients in Poland.

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.

Progressive Collateral Stenosis Leading to Symptomatic Chronic Total Occlusion

We present a case of chronic total occlusion (CTO) in a functional 79-year-old female with no past history of coronary artery disease, who was previously asymptomatic due to robust collateral circulation. A 79-year-old Caucasian female presented to the emergency department complaining of chest pain radiating to the neck, jaw, left arm with associated numbness in the left fingers, that had started earlier in the day. She has no previous cardiac history and never had similar symptoms before. Troponin levels were negative. Nuclear stress test showed findings worrisome for ischemia and was a high-risk exam. The patient underwent diagnostic angiography. There was complete total occlusion of the mid right coronary artery, with collateral circulation supplying the distal right coronary artery territory. Ultimately, it found that progressive stenosis of the left anterior descending (LAD) artery led to inadequate collateral circulation and completely occluded the right coronary artery's territory, causing the patient's new-onset angina. Afterwards, the patient underwent percutaneous coronary intervention (PCI). Successful implantation of two drug-eluting stents occurred. The final angiographic result was 0% residual stenosis and Thrombolysis in Myocardial Infarction (TIMI)-3 flow. CTO affecting one or more coronary arteries is not uncommon in patients taken to the catheterization laboratory. However, despite recent advancements in PCI outcomes, treatment of CTO by PCI remains relatively low, due to fear of adverse outcomes such as cardiac perforations. Recent research has supported the safety of performing PCIs on patients with CTO. This case report further reinforces the need to approach treating CTO via angioplasty.

Prognostic impact of coronary chronic total occlusion on recurrences of ventricular tachyarrhythmias and ICD therapies

BACKGROUND

Despite a few studies evaluating the prognostic impact of coronary chronic total occlusion (CTO) in implantable cardioverter defibrillator (ICD) recipients, the impact of CTO on different types of recurrences of ventricular tachyarrhythmias, as well as their predictors has not yet been investigated in CTO patients.

METHODS

A large retrospective registry was used including all consecutive patients with ventricular tachyarrhythmias undergoing coronary angiography at index from 2002 to 2016. Only ICD recipients with CTO were compared to patients without (non-CTO). Kaplan-Meier and Cox regression analyses were applied for the primary end point of first recurrence of ventricular tachyarrhythmias at 5 years. Secondary end points comprised of the different types of recurrences, first appropriate ICD therapy and all-cause mortality at 5 years.

RESULTS

From a total of 422 consecutive ICD recipients with ventricular tachyarrhythmias at index, at least one CTO was present in 25%. CTO was associated with the primary end point of first recurrence of ventricular tachyarrhythmias at 5 years (55% vs. 39%; log rank p = 0.001; HR = 1.665; 95% CI 1.221-2.271; p = 0.001), as well as increased risk of first appropriate ICD therapy (40% vs. 31%; log rank p = 0.039; HR = 1.454; 95% CI 1.016-2.079; p = 0.041) and all-cause mortality at 5 years (26% vs. 16%; log rank p = 0.011; HR = 1.797; 95% CI 1.133-2.850; p = 0.013). Less developed collaterals (i.e., either ipsi- or contralateral compared to bilateral) and a J-CTO score ≥ 3 were strongest predictors of recurrences in CTO patients at 5 years.

CONCLUSION

A coronary CTO even in the presence of less developed collaterals and more complex CTO category is associated with increasing risk of recurrent ventricular tachyarrhythmias at 5 years in consecutive ICD recipients.

Prognostic impact of collaterals in patients with a coronary chronic total occlusion: A meta-analysis of over 3,000 patients

OBJECTIVES

To assess the prognostic implications of the degree of coronary collaterals on outcomes in patients with a CTO.

BACKGROUND

Coronary chronic total occlusions (CTO) are identified frequently in patients undergoing coronary angiography and have been associated with poorer prognosis. Whether the degree of coronary collaterals, the hallmark of CTOs impacts prognosis, is unknown.

METHODS

A search of EMBASE, MEDLINE, and Cochrane Library was conducted to identify studies reporting on coronary collaterals and risk of all-cause mortality, acute myocardial infarction (AMI) and successful percutaneous coronary intervention (PCI). Patients with Rentrop grade 0 or 1 collaterals were defined as poor collaterals, while Rentrop grade 2 or 3 were defined as robust collaterals.

RESULTS

Twelve studies with a total of 3,369 were included. Patients with robust collaterals did not have lower rates of AMI (OR: 0.89, 95%CI: 0.39-2.04) or lower rates of all-cause mortality (OR: 0.81, 95% CI: 0.42-1.58), however were more likely to have successful PCI (OR: 4.04, 95%CI: 1.10-14.85).

CONCLUSION

The presence of robust collaterals is not associated with lower rates of AMI or mortality, but does increase the likelihood of successful CTO PCI. These results have importance implications with respect to the indications for CTO PCI as well as selecting appropriate patients to undergo the procedure.

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.

Coronary physiology before and after chronic total occlusion treatment: what does it tell us?

Studies performed in the last two decades demonstrate that after successful percutaneous coronary intervention (PCI) of a chronically occluded coronary artery, the physiology of the chronic total occlusion (CTO) vessel and dependent microvasculature does not normalise immediately but improves significantly over time. Generally, there is an increase in fractional flow reserve (FFR) in the CTO artery, a decrease in collateral blood supply and an increase in FFR in the donor artery accompanied by an increase in blood flow and decrease in microvascular resistance in the myocardium supplied by the CTO vessel. Analogous to these physiological changes, positive remodelling of the distal CTO artery also occurs over time, and intravascular imaging can be helpful for analysing distal vessel parameters. Follow-up coronary angiography with physiological measurements after several weeks to months can be helpful and informative in a subset of patients in order to decide upon the necessity for treatment of residual coronary artery stenosis in the vessel distal to the CTO or in the contralateral donor artery, as well as in deciding whether stent optimisation is indicated. We suggest that such physiological guidance of CTO procedures avoids unnecessary overtreatment during the initial procedure, guides interventions at follow-up, and improves our understanding of what PCI in CTO means.

iFR uncovers profound but mostly reversible ischemia in CTOs and helps to optimize PCI results

OBJECTIVES

The study aimed to demonstrate through instant wave-free ratio (iFR) measurements that myocardium distal to a chronic total occlusion (CTO) is ischemic, that ischemia is reversible by PCI, and that iFR assessment after PCI can be used to optimize PCI results.

BACKGROUND

The greatest benefit of revascularization is found in patients with low fractional flow reserve. In patients with CTOs, iFR measurement may be more appropriate to evaluate ischemia as it does not require maximal microvascular vasodilation, which may be hampered by microvascular dysfunction.

METHODS

The iFR was measured in 81 CTO patients, both pre- and post-PCI in 63 patients, and only post-PCI in the following 18 patients. A pressure wire pullback was performed post-PCI if iFR ≤0.89.

RESULTS

The first 63 patients all had significant ischemia distal to the CTO with a median iFR of 0.33 [0.22; 0.44], improving significantly post-PCI to a median iFR of 0.93 [0.89;0.96] (p < .001). In the complete cohort, the median iFR post-PCI was 0.93 [0.86;0.96] but still ≤0.89 in 23 patients (30%). 12 of these patients had further PCI optimization because of a residual focal pressure gradient on pullback, after which only two had a final iFR ≤0.89.

CONCLUSIONS

In CTO patients with an indication for PCI, iFR consistently demonstrated profound myocardial ischemia. Successful PCI immediately relieved ischemia in 70% of patients. In the remaining 30% of cases, a manual iFR pullback proved helpful in guiding further optimization of the PCI result.

The Role of Percutaneous Coronary Intervention in the Treatment of Chronic Total Occlusions: Rationale and Review of the Literature

BACKGROUND

Chronic total occlusion (CTO) of a coronary artery is defined as an occluded segment with no antegrade flow and a known or estimated duration of at least 12 weeks.

OBJECTIVE

We considered the current literature describing the indications and clinical outcomes for denovo CTO- percutaneous coronary intervention (PCI), and discuss the role of CTO-PCI and future directions for this procedure.

METHODS

Databases (PubMed, the Cochrane Library, Embase, EBSCO, Web of Science, and CINAHL were searched and relevant studies of CTO-PCI were selected for review.

RESULTS

The prevalence of coronary artery CTO's has been reported to be ~ 20% among patients undergoing diagnostic coronary angiography for suspected coronary artery disease. Revascularization of any CTO can be technically challenging and a time-consuming procedure with relatively low success rates and may be associated with a higher incidence of complications, particularly at non-specialized centers. However, with an increase in experience and technological advances, several centers are now reporting success rates above 80% for these lesions. There is marked variability among studies in reporting outcomes for CTO-PCI with some reporting potential mortality benefit, better quality of life and improved cardiac function parameters. Anecdotally, properly selected patients who undergo a successful CTO-PCI most often have profound relief of ischemic symptoms. Intuitively, it makes sense to revascularize an occluded coronary artery with the goal of improving cardiovascular function and patient quality of life.

CONCLUSION

CTO-PCI is a rapidly expanding specialized procedure in interventional cardiology and is reasonable or indicated if the occluded vessel is responsible for symptoms or in selected patients with silent ischemia in whom there is a large amount of myocardium at risk and PCI is likely to be successful.

Recovery of Absolute Coronary Blood Flow and Microvascular Resistance After Chronic Total Occlusion Percutaneous Coronary Intervention: An Exploratory Study

Background

This study aimed to investigate longitudinal physiological changes in the recanalized coronary chronic total occlusion (CTO) vessel and its dependent myocardium after successful percutaneous coronary intervention (PCI).

Methods and Results

In this pilot study, 25 patients scheduled for elective CTO PCI with viable myocardium and angiographically visible collaterals were included. Absolute coronary blood flow and absolute microvascular resistance were measured invasively using continuous thermodilution. Measurements were performed immediately after successful CTO PCI and at short‐term follow‐up. In a subgroup of patients, physiological measurements were performed at the predominant donor vessel before CTO PCI, immediately afterwards, and at follow‐up. Absolute coronary blood flow in the recanalized CTO artery increased from 148±53 mL/min immediately after PCI to 221±77 mL/min at follow‐up (P<0.001). In agreement, absolute resistance in the myocardial territory perfused by the CTO artery, decreased from 545±255 Wood units immediately after the procedure to 387±128 Wood units at follow‐up (P=0.014). There were no significant changes in the absolute coronary blood flow and resistance in the predominant donor between baseline and follow‐up. Positive remodeling of the distal CTO vessel with an increase in lumen diameter was observed.

Conclusions

After successful CTO PCI, blood flow in the recanalized artery and microvascular function of the dependent myocardium are not immediately normal but recover over time.

Impact of Specific Crossing Techniques in Chronic Total Occlusion Percutaneous Coronary Intervention on Recovery of Absolute Myocardial Perfusion

Background:

Multiple crossing techniques in chronic total occlusion (CTO) percutaneous coronary intervention have been developed. This study compared recovery of quantitative myocardial blood flow (MBF) after different CTO percutaneous coronary intervention techniques.

Methods:

Consecutive patients with [ 15 O]H 2 O positron emission tomography perfusion imaging before and 3 months after successful CTO percutaneous coronary intervention between 2013 and 2018 were included. Changes in hyperemic MBF, coronary flow reserve, and perfusion defect size were compared between antegrade wire escalation, retrograde wire escalation, antegrade dissection and reentry (ADR), and retrograde dissection and reentry.

Results:

One hundred ninety-three patients were treated with antegrade wire escalation (N=90), retrograde wire escalation (N=24), ADR (N=35), and retrograde dissection and reentry (N=44). Increase in hyperemic MBF (1.19±0.77, 0.94±0.65, 1.09±0.63, and 1.02±0.75 mL·min -1 ·g -1 , respectively; P =0.40) and coronary flow reserve (1.34±1.08, 1.14±1.09, 1.31±0.96, and 1.24±0.99, respectively; P =0.84) and decrease in defect size (3.2±2.1, 3.0±2.2, 2.7±2.1, and 2.9±1.9 segments, respectively; P =0.77) were comparable between the 4 approaches. In addition, recovery of hyperemic MBF was less pronounced after subintimal crossing with knuckle-wire-technique compared with CrossBoss in controlled ADR and retrograde dissection and reentry (0.93±0.69 versus 1.54±0.65 mL·min -1 ·g -1 , P =0.02), and less after reentry using subintimal tracking and reentry in ADR compared with controlled ADR (Stingray) or limited antegrade subintimal tracking (0.60±0.53 versus 1.18±0.54 [ P =0.04] and versus 1.49±0.57 mL·min -1 ·g -1 , [ P <0.01]).

Conclusions:

Recovery of hyperemic MBF, coronary flow reserve, and perfusion defect size after CTO percutaneous coronary intervention was comparable between different approaches. Although sometimes necessary to cross a complex CTO lesion, subintimal knuckle wiring and subintimal tracking and reentry resulted in less hyperemic MBF improvement compared with other subintimal crossing and reentry techniques.

Guiding Principles for Chronic Total Occlusion Percutaneous Coronary Intervention

Outcomes of chronic total occlusion (CTO) percutaneous coronary intervention (PCI) have improved because of advancements in equipment and techniques. With global collaboration and knowledge sharing, we have identified 7 common principles that are widely accepted as best practices for CTO-PCI.  1. Ischemic symptom improvement is the primary indication for CTO-PCI.  2. Dual coronary angiography and in-depth and structured review of the angiogram (and, if available, coronary computed tomography angiography) are key for planning and safely performing CTO-PCI.  3. Use of a microcatheter is essential for optimal guidewire manipulation and exchanges.  4. Antegrade wiring, antegrade dissection and reentry, and the retrograde approach are all complementary and necessary crossing strategies. Antegrade wiring is the most common initial technique, whereas retrograde and antegrade dissection and reentry are often required for more complex CTOs.  5. If the initially selected crossing strategy fails, efficient change to an alternative crossing technique increases the likelihood of eventual PCI success, shortens procedure time, and lowers radiation and contrast use.  6. Specific CTO-PCI expertise and volume and the availability of specialized equipment will increase the likelihood of crossing success and facilitate prevention and management of complications, such as perforation.  7. Meticulous attention to lesion preparation and stenting technique, often requiring intracoronary imaging, is required to ensure optimum stent expansion and minimize the risk of short- and long-term adverse events. These principles have been widely adopted by experienced CTO-PCI operators and centers currently achieving high success and acceptable complication rates. Outcomes are less optimal at less experienced centers, highlighting the need for broader adoption of the aforementioned 7 guiding principles along with the development of additional simple and safe CTO crossing and revascularization strategies through ongoing research, education, and training.

Applicability and Interpretation of Coronary Physiology in the Setting of a Chronic Total Occlusion

Concurrent coronary artery disease in a vessel remote from a chronic total occlusion (CTO) is common and presents a management dilemma. While the use of adjunctive coronary physiology to guide revascularization is now commonplace in the catheterization laboratory, the presence of a CTO provides a unique and specific situation whereby the physiological assessment is more complex and relies on theoretical assumptions. Broadly, the physiological assessment of a CTO relies on assessing the function and regression of collaterals, the assessment of the microcirculation, the impact of collateral steal as well as assessing the severity of a lesion in the donor vessel (the vessel supplying the majority of collaterals to the CTO). Recent studies have shown that physiological assessment of the donor vessel in the setting of a CTO may overestimate the severity of stenosis, and that after revascularization of a CTO, the index of ischemia may increase, potentially altering the need for revascularization. In this review article, we present the current literature on physiological assessment of patients with a CTO, management recommendations and identify areas for ongoing research.