The Presence of a CTO in a Non-Infarct-Related Artery During a STEMI Treated With Contemporary Primary PCI Is Associated With Increased Rates of Early and Late Cardiovascular Morbidity and Mortality: The CTO-TOTAL Substudy

Is it Worthy Enough to Revascularize Chronically Occluded Coronaries?

Chronic total occlusions (CTOs) represent the "final frontier" of coronary interventions with the lowest procedural success rates and the most common reason for incomplete revascularization and referral to coronary artery bypass graft surgery (CABG). CTO lesions are not an infrequent finding during coronary angiography. They are often responsible for enhancing the complexity of the coronary disease burden thereby affecting the final interventional decision in the process. Notwithstanding the modest technical success of CTO-PCI, most of the earlier observational data demonstrated a clear survival benefit free of major cardiovascular events (MACE) in patients undergoing successful CTO revascularization. However, data from recent randomized trials fail to uphold the same survival advantage albeit, showing some trend toward improvement in left ventricular function, quality of life indicators and freedom from fatal ventricular arrythmia. Various guidance statements propose a well-defined role for CTO intervention in specific situations provided criterions for patient selection, appreciable inducible ischemia, myocardial viability and cost-risk-benefit analysis are met.

Percutaneous Coronary Intervention versus Optimal Medical Therapy in Patients with Chronic Total Occlusion: A Meta-Analysis

Background/Objectives: Chronic total occlusion (CTO) is a prevalent finding in patients with coronary artery disease and is associated with increased mortality. Prior reports on the efficacy of percutaneous coronary intervention (PCI) compared to optimal medical therapy (OMT) were controversial. Following the emergence of recently published new evidence, a meta-analysis is warranted. The current meta-analysis assessed the effects of PCI compared to OMT in the treatment of CTO. Methods: A structured literature search was performed. Randomized controlled trials (RCTs) and non-randomized controlled studies of interventions were eligible. The primary outcome was an accumulated composite of cardiac mortality, myocardial infarction and target vessel/lesion revascularization events. Results: Thirty-two studies reporting on 11260 patients were included. Of these, 5712 (50.7%) were assigned to the PCI and 5548 (49.3%) were allocated to the OMT group. The primary outcome occurred in 14.6% of the PCI and 20.1% of the OMT group (12 trials, OR 0.66, 95% CI 0.50 to 0.88, p = 0.005, I2 = 67%). Subgrouping demonstrated a consistent reduction in the primary outcome for the PCI group in RCTs (six trials, OR 0.58, 95% CI 0.33 to 0.99, p = 0.05). The primary outcome reduction was irrespective of the study design, and it was replicable in sensitivity and subgroup analyses. Advantages in other outcomes were rather related to statistical pooling effects and dominated by observational data. Conclusions: CTO-PCI was associated with improved patient-oriented primary outcome compared to OMT in a study-level meta-analysis. This composite outcome effect was mainly driven by target vessel treatment, but a significant reduction in mortality and myocardial infarction was observed, irrespectively. These findings have hypothesis-generating implications. Future RCTs with adequate statistical power are eagerly awaited.

Nomogram to Predict Outcomes After Staged Revascularization in ST-Segment Elevation Myocardial Infarction and Multivessel Coronary Artery Disease

Objective

Approximately 50% of ST-segment elevation myocardial infarction (STEMI) patients have multivessel coronary artery disease (MVD). The management strategy for these patients remains controversial. This study aimed to develop predictive models and nomogram of outcomes in STEMI patients with MVD for better identification and classification.

Methods

The least absolute shrinkage and selection operator (LASSO) method was used to select the features most significantly associated with the outcomes. A Cox regression model was built using the selected variables. One nomogram was computed from each model, and individual risk scores were obtained by applying the nomograms to the cohort. After regrouping patients based on nomogram risk scores into low- and high-risk groups, we used the Kaplan-Meier method to perform survival analysis.

Results

The C-index of the major adverse cardiovascular event (MACE)-free survival model was 0·68 (95% CI 0·62-0·74) and 0·65 [0·62-0·68]) at internal validation, and that of the overall survival model was 0·75 (95% CI 0·66-0·84) and (0·73 [0·65-0·81]). The predictions of both models correlated with the observed outcomes. Low-risk patients had significantly lower probabilities of 1-year or 3-year MACEs (4% versus 11%, P= 0.003; 7% versus 15%, P=0.01, respectively) and 1-year or 3-year all-cause death (1% versus 3%, P=0.048; 2% versus 7%, respectively, P=0.001) than high-risk patients.

Conclusion

Our nomograms can be used to predict STEMI and MVD outcomes in a simple and practical way for patients who undergo primary PCI for culprit vessels and staged PCI for non-culprit vessels.

The Presence of Chronic Total Occlusion in Noninfarct-Related Arteries Is Associated With Higher Mortality and Worse Patient Outcomes Following Percutaneous Coronary Intervention for STEMI: A Systematic Review, Meta-Analysis and Meta-Regression

Reperfusion therapy with percutaneous coronary intervention improves outcomes in patients with ST-elevation myocardial infarction. We conducted a meta-analysis to assess the impact of chronic total occlusion (CTO) in noninfarct-related artery on the outcomes of these patients. Comprehensive searches were performed using PubMed, Google Scholar, and EMBASE. The primary endpoint was the 30-day mortality rate, with secondary endpoints including all-cause mortality, repeat myocardial infarction, and stroke. Forest plots were created for the pooled analysis of the results, with statistical significance set at P < 0.05. A total of 19 studies were included in this meta-analysis, with 23,989 patients (3589 in CTO group and 20,400 in no-CTO group). The presence of CTO was associated with significantly higher odds of 30-day mortality [18.38% vs 5.74%; relative risk (RR), 3.69; 95% confidence intervals (CI), 2.68-5.07; P < 0.00001], all-cause mortality (31.00% vs 13.40%; RR, 2.79; 95% CI, 2.31-3.37; P < 0.00001), cardiovascular-related deaths (12.61% vs 4.1%; RR, 2.61; 95% CI, 1.99-3.44; P < 0.00001), and major adverse cardiovascular events (13.64% vs 9.88%; RR, 2.08; 95% CI, 1.52-2.86; P < 0.00001) than the non-CTO group. No significant differences in repeated myocardial infarction or stroke were observed between the CTO and non-CTO groups. Our findings underscore the need for further research on the benefits and risks of performing staged or simultaneous percutaneous coronary intervention for CTO in the noninfarct-related artery in patients with ST-elevation myocardial infarction.

Factors associated with all-cause mortality in patients with coronary artery chronic total occlusions undergoing revascularization (percutaneous coronary intervention or surgery) or medical treatment

Aim    Chronic total occlusion of a coronary artery (CTO) is a predictor of early and late cardiovascular mortality and poor cardiovascular outcomes in patients with coronary artery disease. The purpose of this study was to identify predictors of all-cause mortality in CTO patients that underwent invasive treatment.Material and methods    Patients between 2012 and 2018 with CTO in at least one vessel, as demonstrated by coronary angiography, were included retrospectively in the study. The patients were divided into two groups, an intervention group (percutaneous and surgical revascularization) and a medical group.Results    A total of 543 patients were studied, 152 females (28%) and 391 males (72%). The median follow-up period was 49 (26-72) mos. A total of 186 (34.2%) patients in the medical group and 357 (65.8%) patients in the invasive therapy group were followed. The 5-yr death rate was observed in 50 (26.9%) patients in the medical group and 53 (14.8%) patients in the intervention group, and it was found to be statistically higher in the medical group (p=0.001). In multivariable analysis, heart failure (odds ratio (OR): 1.92, 95% CI: 1.18-3.14; p=0.01), higher glucose levels (OR: 1.05, 95% CI: 1,02-1.08; p=0.04), lower albumin levels (OR: 0.49, 95% Cl: 0.32-0.72; p=0.001), SYNTAX score (OR: 1.03, 95% CI: 1.01-1.05; p=0.001), and CTO (≥2 occluded artery) (OR: 0.42, 95% CI: 0.22-0.72; p=0.01) were independent factors for all-cause mortality.Conclusion    In comparison to the revascularized group, there was an increase in mortality among CTO patients treated medically. Heart failure, SYNTAX score, albumin, glucose, and CTO (≥2 occluded arteries) were independent risk factors for all-cause mortality.

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.

Impact of coronary artery bypass grafting (CABG) on coronary collaterals in patients with a chronic total occlusion (CTO)

Chronic total occlusions (CTO) are found commonly in patients with prior coronary artery bypass grafting (CABG). We sought to determine the effect of CABG on collateral robustness in patients with a CTO. Patients with a CTO diagnosed on coronary angiography between July 2010 and December 2019 were included in this study. Patients were classified as either CTO supplied by a functional graft, CTO supplied by collaterals from a non-grafted donor vessel (non-grafted) or a CTO supplied by collaterals from a grafted donor vessel (grafted). The degree of collateral robustness was determined by the Rentrop classification and collateral connection (CC) grade. Demographic, angiographic and clinical outcomes were recorded. A total of 2088 CTO lesions were identified, of which 878 (42.0%) were supplied by a functional graft, 994 (47.6%) CTOs were supplied by a non-grafted donor vessel and 216 (10.3%) CTOs were supplied by a grafted donor vessel. CTOs supplied by a grafted donor vessel had lower rates of robust collaterals (37.0% vs 83.0%, p < 0.0001) with less mature collaterals as determined by the Rentrop grade (p < 0.0001) and CC grade (p < 0.0001) as compared to CTOs supplied by a non-grafted donor vessel. In patients with a previous CABG, a grafted donor vessel results in less robust coronary collaterals with lower Rentrop and CC grade compared to an ungrafted donor vessel. This may be attributable to changes in coronary blood flow and shear stress, and may be a factor in the lower procedural success rates for CTO intervention in patients with prior CABG.

Influence of Obstructive Sleep Apnoea on Outcomes in Patients With ST Elevation Myocardial Infarction (STEMI): the Role of the Coronary Collateral Circulation

BACKGROUND

Obstructive sleep apnoea (OSA) occurs frequently in patients with coronary artery disease, with associated intermittent hypoxia a possible stimulus for coronary collateral recruitment through ischaemic preconditioning. We sought to determine whether OSA affects recruitment of coronary collaterals and prognosis of patients presenting with ST elevation myocardial infarction (STEMI).

METHODS

Patients with a STEMI undergoing percutaneous coronary intervention (PCI) from July 2010 to December 2019 were reviewed. Electronic medical records were accessed to determine documented patient history of OSA. Patients with robust collaterals were defined as Rentrop grade 2 or 3.

RESULTS

1,863 patients were included, of which 143 (7.7%) patients had documented evidence of OSA in their health record. Patients with OSA had a higher body mass index (BMI) (30.2 kg/m² vs 27 kg/m², p<0.0001), greater rate of hypertension (61.1% vs 45.1%, p<0.0001), hypercholesterolaemia (47.4% vs 38.4%, p<0.05) and diabetes mellitus (22.6% vs 15.9%, p<0.05). Patients with OSA were more likely to have robust coronary collaterals (OR: 2.2 [95% CI: 1.5-3.2]) and a lower rate of left ventricular (LV) impairment (50.7% vs 63.1%, p<0.01), a higher LV ejection fraction (50.3% vs 46.7%, p<0.0001) and a lower peak troponin-I level (26,452 ng/L vs 39,469 ng/L, p<0.01). There were no differences in rates of in-hospital or longer term mortality, in patients with OSA compared to those without.

CONCLUSIONS

Patients with documented OSA presenting with STEMI appear to have more robust coronary collaterals observed on angiography which likely mediates lower myocardial necrosis. Broader implications of this finding on treatment require further investigation.

Does multivessel revascularization fit all patients with STEMI and multivessel coronary artery disease? A systematic review and meta-analysis

Objective

We sought to assess the relative merits of different revascularization strategies in patients with ST-segment elevation myocardial infarction (STEMI) and multivessel coronary artery disease complicated by cardiogenic shock or chronic total occlusion (CTO).

Background

Recent randomized trials and meta-analysis have suggested that multivessel percutaneous coronary intervention (PCI) is associated with better outcomes in patients with STEMI and multivessel coronary artery disease, however, patients complicated by cardiogenic shock or CTO were excluded.

Methods

Studies that compared multivessel PCI (immediate or staged) with culprit-only PCI in patients with STEMI and multivessel coronary artery disease complicated by cardiogenic shock or CTO were included. Random odd ratio (OR) and 95% confidence interval (CI) were conducted.

Results

Sixteen studies with 8695 patients complicated by cardiogenic shock and eight studies with 2259 patients complicated by CTO were included. In patients complicated by cardiogenic shock, a strategy of CO-PCI was associated with lower risk for short-term renal failure (OR: 0.75; 95% CI: 0.61–0.93; I² = 0.0%), with no significant difference in MACE, all-cause mortality, re-infarction, revascularization, cardiac death, heart failure, major bleeding, or stroke compared with an immediate MV-PCI strategy. In patients complicated by CTO, a strategy of CO-PCI was associated with higher risk for long-term MACE (OR: 2.06; 95% CI: 1.39–3.06; I² = 54.0%), all-cause mortality (OR: 2.89; 95% CI: 2.09–4.00; I² = 0.0%), cardiac death (OR: 3.12; 95% CI: 2.05–4.75; I² = 16.8%), heart failure (OR: 1.99; 95% CI: 1.22–3.24; I² = 0.0%), and stroke (OR: 2.80; 95% CI: 1.04–7.53; I² = 0.0%) compared with a staged MV-PCI strategy, without any difference in re-infarction, revascularization, or major bleeding.

Conclusions

For patients with STEMI and multivessel coronary artery disease complicated by cardiogenic shock, an immediate multivessel PCI was not advocated due to a higher risk for short-term renal failure, whereas for patients complicated by CTO, a staged multivessel PCI was advocated due to reduced risks for long-term MACE, all-cause mortality, cardiac death, heart failure, and stroke.

Prognostic impact of non-culprit chronic total occlusion over time in patients with ST-elevation myocardial infarction treated with primary percutaneous coronary intervention

AIMS

Previous studies indicated that a chronic total occlusion (CTO) in a non-infarct-related artery is linked to higher mortality mainly in the acute setting in patients with ST-elevation myocardial infarction (STEMI). Our aim was to assess the temporal distribution of mortality risk associated with non-culprit CTO over years after STEMI.

METHODS AND RESULTS

The study included 8679 STEMI patients treated with primary percutaneous coronary intervention (PCI). Kaplan-Meier cumulative mortality curves for non-culprit CTO vs. no CTO were compared with log-rank test, with landmarks set at 30 days and 1 year. Adjusted Cox regression models were constructed to assess the impact of non-culprit CTO on mortality over different time intervals. Tests for interaction were pre-specified between non-culprit CTO and acute heart failure and left ventricular ejection fraction. The primary outcome variable was all-cause mortality, and the median follow-up was 5 years. Non-culprit CTO was present in 11.6% of patients (n = 1010). Presence of a CTO was associated with increased early [30-day adjusted hazard ratio (HR) 1.91, 95% confidence interval (CI) 1.54-2.36; P < 0.001] and late mortality (5-year adjusted HR 1.66, 95% CI 1.42-1.95; P < 0.001). Landmark analyses revealed an annual two-fold increase in mortality in patients with vs. without a CTO after the first year of follow-up. The observed pattern of mortality increase over time was independent of acute or chronic LV impairment.

CONCLUSIONS

Non-culprit CTO is independently associated with mortality over 5 years after primary PCI for STEMI, with a constant annual two-fold increase in the risk of death beyond the first year of follow-up.

Relation of Obstructive Sleep Apnea in Patients With a Coronary Chronic Total Occlusion to Coronary Collaterals and Mortality

A chronic total occlusion (CTO) is frequently identified in patients undergoing coronary angiography. The prognostic implications of intermittent hypoxia from obstructive sleep apnea (OSA) on patients with a CTO, and effects on collateral recruitment are unknown. The aim of this study was to determine the prevalence, vascular effects, and prognostic implications of the presence of OSA in patients with a CTO. Patients with a CTO between July 2010 and December 2019 were reviewed. Electronic medical records were accessed to determine documented patient history of OSA, demographics, and clinical course. Patients with robust collateral recruitment were defined as Rentrop grade 2 or 3. A total of 948 patients were included in the study, of which 127 (13.4%) had a documented history of OSA. These patients were younger (67.0 years vs 70.6 years, p < 0.01), had a higher body mass index (29.6 kg/m² vs 26.7 kg/m², p < 0.0001), higher rates of hypertension (91.3% vs 83.2%, p < 0.05), higher rates of smokers (63.3% vs 49.0%, p < 0.01) and more use of β-blockers (79% vs 68.5%, p < 0.05) and statins (92.7% vs 82.1%, p < 0.01). A documented history of OSA was independently associated with robust collaterals (OR 3.0 95%CI 1.5 to 5.8, p < 0.01) and lower mortality (HR 0.3 95% CI 0.1 to 0.7, p < 0.01) with a mean survival of 10.8 years, as compared to 8.1 years (log rank p < 0.0001). In conclusion, in patients with a CTO, documented OSA is independently associated with more robust coronary collaterals and lower mortality. The possible cardioprotective implications of intermittent hypoxia in OSA, as well as treatment effect requires further investigation.

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.

Late Survival Benefit of Percutaneous Coronary Intervention Compared With Medical Therapy in Patients With Coronary Chronic Total Occlusion: A 10-Year Follow-Up Study

Background

As an initial treatment strategy, percutaneous coronary intervention (PCI) for coronary chronic total occlusion (CTO) did not show midterm survival benefits compared with optimal medical therapy (OMT). We sought to evaluate the benefit of PCI compared with OMT in patients with CTO over extended long‐term follow‐up.

Methods and Results

Between March 2003 and February 2012, 2024 patients with CTO were enrolled in a single‐center registry and followed for ≈10 years. We excluded patients with CTO who underwent coronary artery bypass graft (n=477) and classified patients into the CTO‐PCI group (n=883) or OMT group (n=664) according to initial treatment strategy. Patients with multivessel disease received PCI for obstructive non‐CTO lesions in both groups. In the CTO‐PCI group, 699 patients (79.2%) underwent successful revascularization. The CTO‐PCI group had a lower 10‐year rate of cardiac death (10.4% versus 22.3%; hazard ratio [HR], 0.44 [95% CI, 0.32–0.59]; P<0.001) than the OMT group. After propensity score matching analyses, the CTO‐PCI group had a lower 10‐year rate of cardiac death (13.6% versus 20.8%; HR, 0.64 [95% CI, 0.45–0.91]; P=0.01) than the OMT group. The relative reduction in cardiac death at 10 years was mainly driven by a relative reduction between 3 and 10 years (8.3% versus 16.6%; HR, 0.43 [95% CI, 0.27–0.71]; P<0.001) but not at 3 years (5.7% versus 5.0%; HR, 1.12 [95% CI, 0.63–2.00]; P=0.71). The beneficial effects of CTO‐PCI were consistent among subgroups.

Conclusions

As an initial treatment strategy, CTO‐PCI might reduce late cardiac death compared with OMT in patients with CTO. Extended follow‐up of randomized trials may confirm the findings of the present study.

Medical therapy vs early revascularization in diabetics with chronic total occlusions: A meta-analysis and systematic review

BACKGROUND

Management of chronic total occlusions (CTO) in diabetics is challenging, with a recent trend towards early revascularization [ER: Percutaneous coronary intervention (PCI) and bypass grafting] instead of optimal medical therapy (OMT). We hypothesize that ER improves morbidity and mortality outcomes in diabetic patients with CTOs as compared to OMT.

AIM

To determine the long term clinical outcomes and to compare morbidity and mortality between OMT and ER in diabetic patients with CTOs.

METHODS

Potentially relevant published clinical trials were identified in Medline, Embase, chemical abstracts and Biosis (from start of the databases till date) and pooled hazard ratios (HR) computed using a random effects model, with significant P value < 0.05. Primary outcome of interest was all-cause death. Secondary outcomes included cardiac death, prompt revascularization (ER) or repeat myocardial infarction (MI). Due to scarcity of data, both Randomized control trials and observational studies were included. 4 eligible articles, containing 2248 patients were identified (1252 in OMT and 1196 in ER). Mean follow-up was 45-60 mo.

RESULTS

OMT was associated with a higher all-cause mortality [HR: 1.70, 95% confidence interval (CI): 0.80-3.26, P = 0.11] and cardiac mortality (HR: 1.68, 95%CI: 0.96-2.96, P = 0.07). Results were close to significance. The risk of repeat MI was almost the same in both groups (HR: 0.97, 95%CI: 0.61-1.54, P = 0.90). Similarly, patients assigned to OMT had a higher risk of repeat revascularization (HR: 1.62, 95%CI: 1.36-1.94, P < 0.00001). Sub-group analysis of OMT vs PCI demonstrated higher all-cause (HR: 1.98, 95%CI: 1.36-2.87, P = 0.0003) and cardiac mortality (HR: 1.87, 95%CI: 0.96-3.62, P = 0.06) in the OMT group. The risk of repeat MI was low in the OMT group vs PCI (HR: 0.53, 95%CI: 0.31-0.91, P = 0.02). Data on repeat revascularization revealed no difference between the two (HR: 1.00, 95%CI: 0.52-1.93, P = 1.00).

CONCLUSION

In diabetic patients with CTO, there was a trend for improved outcomes with ER regarding all-cause and cardiac death as compared to OMT. These findings were reinforced with statistical significance on subgroup analysis of OMT vs PCI.

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.

Prognostic implications of the rapid recruitment of coronary collaterals during ST elevation myocardial infarction (STEMI): a meta-analysis of over 14,000 patients

Acute coronary collateralisation of an infarct-related arterial (IRA) territory may be identified during angiography for ST elevation myocardial infarction (STEMI). Whether the presence or absence of these collaterals affects outcomes remains uncertain. A search of EMBASE, MEDLINE and Cochrane Library, using the Preferred Reporting Items for Systematic reviews and Meta-Analysis (PRISMA) guidelines was conducted to identify studies which reported on the association between coronary collaterals and in-hospital and longer term mortality, left ventricular ejection fraction (LVEF), risk of repeat acute myocardial infarction (AMI) and repeat revascularisation. Patients with Rentrop grade 0 or 1 were defined as poor collaterals whilst those with Rentrop grade two or three were defined as those with robust collaterals. Studies were eligible if they included patients ≥ 18 years of age who had immediate coronary angiography for STEMI. Included studies were observational which recorded the degree of collateral blood flow to the IRA. Two investigators reviewed all citations using a predefined protocol with final consensus for all studies, the data from which was then independently entered to ensure fidelity of results. Inverse variance random effects model for the meta-analysis along with risk of bias assessment was performed. 20 studies with a total of 14,608 patients were identified and included in the analysis. Patients with robust collaterals had lower mortality (OR 0.55, 95% CI 0.48-0.64), both in-hospital (OR 0.47, 95% CI 0.35-0.63) and longer term (OR 0.58, 95% CI 0.46-0.75). Patients with robust collaterals also had a higher mean LVEF (SMD 0.23, 95% CI 0.10-0.37). There was no difference in the rates of AMI or repeat revascularisation between patients with robust or poor collaterals. The presence of robust collaterals during STEMI is associated with reduced in-hospital and longer term mortality and improved left ventricular function. These findings have implications for prognostication and identifying patients who require close monitoring following STEMI.

Effect of Recruitment of Acute Coronary Collaterals on In-Hospital Mortality and on Left Ventricular Function in Patients Presenting With ST Elevation Myocardial Infarction

Recruitment of the coronary collateral circulation is frequently observed during ST elevation myocardial infarction (STEMI) and is of uncertain significance. The aim of this study was to identify and determine the predictors and prognostic implications of the presence of robust collaterals during STEMI. All patients presenting to a large tertiary centre with a STEMI undergoing percutaneous coronary intervention from 2010 to 2018 were reviewed. Patients with poor collateral recruitment were defined as those with Rentrop grade 0 or 1 collaterals, whilst patients with robust collateral recruitment were defined as Rentrop grade 2 or 3. A total of 1,625 patients were included in the study, with 1,280 (78.8%) patients having poor collateral recruitment and 345 patients (21.2%) having robust collateral recruitment. Patients with robust collaterals were younger (63.1 vs 65.1 years, p < 0.05), had a longer ischemic time (628.5 minutes vs 433.1 minutes, p < 0.0001), and more likely to have a chronic total occlusion of a noninfarct related artery (10.4% vs 5.3%, p < 0.001). The presence of robust collaterals was associated with higher rates of normal or mildly impaired left ventricular function (83.5% vs 63.2%, p < 0.0001) and lower in-hospital mortality (2.1% vs 7.6%, p < 0.0001). After correcting for left ventricular function, collateral recruitment was not an independent predictor of mortality. In conclusion, in patients presenting with STEMI, the presence of robust coronary collaterals appears to be associated with improved left ventricular function. Further research is required to identify mechanisms of collateral maturation and recruitment.

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.

Animal chronic total occlusion models: A review of the current literature and future goals

Coronary chronic total occlusions (CTOs) are commonly found in patients undergoing coronary angiography and is associated with poorer prognosis than in those patients with other forms of stable coronary artery disease. As such, with an increasing appreciation of this clinical entity, there is a need to identify, firstly the pathophysiological process driving its formation, as well as new percutaneous strategies for revascularisation with long term durability and improved outcomes. An appropriate, reliable and reproducible animal model is vital for both of these objectives. We review the prevalence of spontaneous collaterals in different species, as well as review the current literature with respect to animal models of CTOs, and compare and contrast the advantages and disadvantages of these differing models. Whilst both extrinsic compression models and endoluminal procedures may create situations analogous to a CTO in a human, the ideal animal model of a CTO will include an occluded artery, functional collaterals and a viable myocardium. This would allow study of the process driving collateral formation and arteriogenesis as well as percutaneous intervention strategies for both acute and long term benefits.