Impact of multivessel coronary disease on long-term mortality in patients with ST-elevation myocardial infarction is due to the presence of a chronic total occlusion

The impact of successful chronic total occlusion percutaneous coronary intervention on clinical outcomes: a tertiary single-center analysis

Background

The benefit of chronic total occlusion (CTO)-percutaneous coronary intervention (PCI) is controversial because of a lack of high-quality evidence. We aim to evaluate the impact of CTO-PCI on symptoms, quality of life and mortality.

Methods

We conducted a retrospective single center study of patients with CTO-PCI in a tertiary center in Austria. The study outcomes were Canadian Cardiovascular Society (CCS) angina score, quality of life measured by Seattle Angina Questionnaire (SAQ), and death at median follow up for patients with successful vs. failed CTO-PCI.

Results

A total of 300 patients underwent CTO-PCI for coronary artery disease, of which 252 (84%) were technically successful with median follow up of 3.4 years. There were no significant differences in in-hospital or all-cause mortality, major adverse cardiovascular event, or stent-related complications between the groups of failed and successful CTO-PCI. Among patients with successful CTO-PCI there was a significant improvement in CCS score, which was not found for the group with failed CTO-PCI. Successful reopening was associated with significant benefits of the SAQ domains of angina with stressful activity [3.7 ± 0.9 vs. 3.1 ± 0.5, p = 0.004, use of nitrates (4.7 ± 0.5 vs. 3.0 ± 1.0) p = 0.005] and satisfaction from angina relief (4.4 ± 1.1 vs. 3.6 ± 1.4 p < 0.001).

Conclusion

While there was no significant difference in mortality, successful CTO-PCI was associated with greater reduction in angina and the use of nitrates compared to unsuccessful CTO-PCI.

Chronic total occlusion in non-ST elevation myocardial infarction - A multi-centre observational study

OBJECTIVES

To evaluate the characteristics and outcomes of patients with a chronic total occlusion (CTO) in a Non-ST Elevation Myocardial Infarction (NSTEMI) cohort.

BACKGROUND

There is limited data on the clinical characteristics, revascularisation strategies and outcomes of patients presenting with a NSTEMI and a CTO.

METHODS

Retrospective analysis of a six-centre percutaneous coronary intervention (PCI) registry in the UK between January 2015 and December 2020 was performed. Patients with a NSTEMI with and without a CTO were compared for baseline characteristics and outcomes.

RESULTS

There were 17,355 NSTEMI patients in total of whom 1813 patients had a CTO (10.4 %). Patients with a CTO were more likely to be older (CTO: 67.8 (±11.5) years vs. no CTO: 67.2 (±12) years, p = 0.04), male (CTO: 81.1 % vs.71.9 %, p < 0.0001) with a greater prevalence of cardiovascular risk factors. All-cause mortality at 30 days: HR 2.63, 95 % CI 1.42-4.84, p = 0.002 and at 1 year: HR: 1.87, 95 % CI 1.25-2.81, p = 0.003 was higher in the CTO cohort. CTO patients who underwent revascularisation were younger (Revascularisation 66.4 [±11.7] years vs. no revascularisation 68.4 [±11.4] years, p = 0.001). Patients with failed CTO revascularisation had lower survival (HR 0.21, 95 % CI 0.10-0.42, p < 0.0001). The mean time to revascularisation was 13.4 days. There was variation in attempt at CTO revascularisation between the 6 centres for (16 % to 100 %) with success rates ranging from 65 to 100 %.

CONCLUSIONS

In conclusion, the presence of a CTO in NSTEMI patients undergoing PCI was associated with worse in-hospital and long-term outcomes.

Right Ventricular Myocardial Infarction-A Tale of Two Ventricles: JACC Focus Seminar 1/5

Right ventricular infarction (RVI) complicates 50% of cases of acute inferior ST-segment elevation myocardial infarction, and is associated with high in-hospital morbidity and mortality. Ischemic right ventricular (RV) systolic dysfunction decreases left ventricular preload delivery, resulting in low-output hypotension with clear lungs, and disproportionate right heart failure. RV systolic performance is generated by left ventricular contractile contributions mediated by the septum. Augmented right atrial contraction optimizes RV performance, whereas very proximal occlusions induce right atrial ischemia exacerbating hemodynamic compromise. RVI is associated with vagal mediated bradyarrhythmias, both during acute occlusion and abruptly with reperfusion. The ischemic dilated RV is also prone to malignant ventricular arrhythmias. Nevertheless, RV is remarkably resistant to infarction. Reperfusion facilitates RV recovery, even after prolonged occlusion and in patients with severe shock. However, in some cases hemodynamic compromise persists, necessitating pharmacological and mechanical circulatory support with dedicated RV assist devices as a "bridge to recovery."

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.

The impact of concomitant chronic total occlusion on clinical outcomes in patients undergoing transcatheter aortic valve replacement: a large single-center analysis

Background

Coronary artery disease (CAD) is a common finding in patients with severe aortic stenosis undergoing transcatheter aortic valve replacement (TAVR). However, the impact on prognosis of chronic total occlusions (CTOs), a drastic expression of CAD, remains unclear.

Methods and results

We retrospectively reviewed 1,487 consecutive TAVR cases performed at a single tertiary care medical center. Pre-TAVR angiograms were analyzed for the presence of a CTO. At the time of TAVR, 11.2% (n = 167) patients had a CTO. There was no significant association between the presence of a CTO and in-hospital or 30-day mortality. There was also no difference in long-term survival. LV ejection fraction and mean aortic gradients were lower in the CTO group.

Conclusions

Our analysis suggests that concomitant CTO lesions in patients undergoing TAVR differ in their risk profile and clinical findings to patients without CTO. CTO lesion per se were not associated with increased mortality, nevertheless CTOs which supply non-viable myocardium in TAVR population were associated with increased risk of death. Additional research is needed to evaluate the prognostic significance of CTO lesions in TAVR patients.

Percutaneous coronary intervention versus coronary artery by-pass grafting in premature coronary artery disease: What is the evidence? -A narrative review

Coronary artery disease (CAD) remains one of the leading causes of death globally. In the United States of America, in 2016, 19% of all patients under the age of 65 died of cardiovascular disease despite improvements in primary prevention. The premature clinical onset of symptoms in the young population (<60 years) is much more aggressive than in the older population, and the overall long-term prognosis is poor. CAD appears to have a rapidly progressive form in those under the age of 60 due to genetic predisposition, smoking, and substance abuse, however, the ideal management strategy is still yet to be established. The two primary methods of establishing coronary revascularization are percutaneous coronary intervention (PCI) and coronary artery bypass graft (CABG). Despite the increasing prevalence of CAD in the young population, they are consistently underrepresented in major randomized clinical trials of each revascularization strategy. Both CABG and PCI are known to have similar survival rates, but PCI is associated with higher repeat revascularization rate. Many argue this may be due to the progressive nature of CAD combined with the vessel patency time required in a patient under 60 with potentially another 20-30 years of life. There is little in literature regarding the outcomes of these various revascularization strategies in populations under 60 years with CAD. This review summarises the current evidence for each revascularisation strategy in patients under the age of 60 and suggests future avenues of research for this unique age group.

Outcomes of Transcatheter Aortic Valve Replacement With and Without Index Chronic Total Occlusion of Coronary Artery: A Propensity Matched Analysis

Transcatheter aortic valve replacement (TAVR) utilization is increasing, along with procedural success. Coronary angiography is frequently performed before the TAVR procedure for coronary artery disease workup. Chronic total occlusion (CTO) of the coronary artery shares common risk factors with aortic stenosis and could be challenging, especially in terms of procedural safety. The outcomes of TAVR among patients with concomitant CTO are not extensively studied. We analyzed the National Inpatient Sample database between October 2015 and December 2020 to evaluate the clinical characteristics, procedural safety, and outcomes among patients who underwent TAVR who had concomitant CTO lesions. A total of 304,330 TAVRs were performed between 2015 and 2020, 5,235 of which (1.72%) were in patients with TAVR-CTO and 299,095 (98.28%) in those with TAVR-no CTO. After propensity matching, there was no difference in the odds of in-hospital mortality (adjusted odds ratio [aOR] 1.28, 95% confidence interval [CI] 0.94 to 1.75, p = 0.11). However, TAVR-CTO was associated with an increased incidence of acute myocardial infarction (aOR 1.27, 95% CI 1.05 to 1.53, p = 0.01), cardiac arrest (aOR, 2.60, 95% CI 1.64 to 4.11, p <0.0001), and need for mechanical circulatory support (aOR 2.6, 95% CI 1.88 to 3.59, p <0.0001). There was no difference in the incidence of stroke, major bleeding, complete heart block, or requirement for permanent pacemaker between the 2 groups. However, the TAVR-CTO cohort had a slightly greater length of stay and total hospitalization cost. TAVR is a relatively safe procedure among those with concomitant CTO lesions; however, it is associated with a greater incidence of acute myocardial infarction, cardiac arrest, and requirement for mechanical circulatory support.

The impact of chronic total occlusions in patients undergoing transcatheter aortic valve replacement: A systematic review and meta-analysis

Coronary artery disease (CAD) is frequently encountered in patients evaluated for transcatheter aortic valve replacement (TAVR) due to severe aortic stenosis. The prognostic relevance of chronic total occlusions (CTOs) in this setting is poorly understood. We conducted a search of MEDLINE and EMBASE to identify studies evaluating patients who underwent TAVR and evaluated outcomes depending on the presence of coronary CTOs. Pooled analysis was performed to estimate the rate and risk ratio for mortality. Four studies involving 25,432 patients fulfilled the inclusion criteria. The follow up ranged from in-hospital outcomes to 8-years follow-up. Coronary artery disease was present in 67.8% to 75.5% of patients in 3 studies which reported this variable. The prevalence of CTOs varied between 2% and 12.6% in this cohort. The presence of CTOs was associated with increase in length of stay (8.1 ± 8.2 vs. 5.9 ± 6.5, p < 0.01), cardiogenic shock (5.1% vs. 1.7%, p < 0.01), acute myocardial infarction (5.8% vs. 2.8%, p = 0.02) and acute kidney injury (18.6% vs. 13.9%, p = 0.048). The pooled 1-year death rate revealed 41 deaths in 165 patients in the CTO group and 396 deaths in 1663 patients with no CTO ((24.8%) vs. (23.8%)). The meta-analysis of death with CTO versus no CTO showed a nonsignificant trend toward increased mortality with CTOs (risk ratio 1.11 95% CI 0.90-1.40, I²  = 0%). Our analysis suggests that concomitant CTO lesions in patients undergoing TAVR are common, and its presence was associated with increased in-hospital complications. However, CTO presence by itself was not associated with increased long-term mortality, only a nonsignificant trend toward an increased risk of death in patients with CTO was found. Further studies are warranted to assess the prognostic relevance of CTO lesion in TAVR patients.

In-Hospital Outcomes of Chronic Total Occlusion Percutaneous Coronary Interventions in Heart failure patients

In-hospital outcomes of chronic total occlusion Percutaneous Coronary Interventions (CTO PCI) in heart failure patients has not been evaluated on a national base and was the focus of this investigation. We used the Nationwide Inpatient Sample database from 2008 to 2014 to identify adults with single vessel CTO PCI for stable ischemic heart disease (SIHD). Patients were divided into 3 groups: patients without heart failure, heart failure with reduced ejection fraction (HFrEF) and heart failure with preserved ejection fraction (HFpEF). Clinical characteristics and in-hospital outcomes were studied using relevant statistics. Multiple logistic regression models were performed to assess in-hospital mortality, acute renal failure, and the use of mechanical support devices. Of 112,061 inpatients with SIHD from 2008 to 2014 undergoing CTO PCI, 21,185 (19%) had HFrEF and 3309 (3%) had HFpEF. Compared to patients without heart failure, HFrEF and HFpEF patients were older (mean age 69.2 vs 66.3, 70.3 vs 66.3 respectively, P < 0.001), had more comorbidities and higher acute in-hospital complications. HFrEF patients had higher adjusted in-hospital mortality [AOR 1.73, 95% CI (1.21-2.48)], acute renal failure [AOR 2.68, 95% CI (2.34-3.06)], and need for mechanical support [AOR 2.76, 95% CI (2.17-3.51)]. Compared to patients without heart failure, HFpEF patients had similar mortality and need for mechanical support, but higher incidence of acute renal failure. Older age was significantly associated with increased in-hospital mortality. chronic total occlusion PCI in patients with heart failure is associated with higher in-hospital morbidity and mortality and warrants further investigation to optimize health care delivery.

Impact of chronic total occlusion in a non-infarct-related coronary artery on contrast-associated nephropathy in acute ST-elevation myocardial infarction

OBJECTIVES

Co-existing chronic total occlusion (CTO) in a non-infarct-related artery (IRA) might serve as an important trigger of adverse outcomes in ST-segment elevation myocardial infarction (STEMI). Therefore, we planned to analyse the potential impact of non-IRA CTO on the evolution of contrast-associated nephropathy (CAN) in STEMI patients managed with primary percutaneous coronary intervention (P-PCI).

METHODS

A total of 537 subjects with STEMI undergoing P-PCI during the first 12 h after the onset of their symptoms were enrolled in this retrospective study. The subjects were categorised based on the angiographic presence of non-IRA CTO. Moreover, the subjects were also divided into 2 groups based on their CAN status following P-PCI (CAN (+) and CAN (-)).

RESULTS

Co-existing non-IRA CTO was demonstrated in 86 subjects (16%). During the hospitalisation period, we identified 81 (15.1%) subjects with CAN. Subjects with non-IRA CTO had a significantly higher incidence of CAN compared with those without (56 [12.4%] vs 25 [29.1%], respectively, p < 0.001). In a logistic regression analysis, an existing non-IRA CTO (odds ratio: 2.840, 95%CI: 1.451-5.558, p = 0.002), as well as age, haemoglobin, diabetes mellitus, creatinine, and white blood cell count, were independent of predictors of CAN.

CONCLUSION

In STEMI patients managed with P-PCI, a co-existing non-IRA CTO had an independent association with the evolution of CAN.

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.

Staged Revascularization for Chronic Total Occlusion in the Non-IRA in Patients with ST-segment Elevation Myocardial Infarction Undergoing Primary Percutaneous Coronary Intervention: An Updated Systematic Review and Meta-analysis

Objectives: Meta-analysis was performed to evaluate the effect of staged revascularization with concomitant chronic total occlusion (CTO) in the non-infarct-associated artery (non-IRA) in patients with ST-segment elevation myocardial infarction (STEMI) treated with primary percutaneous coronary intervention (p-PCI).Methods: Various electronic databases were searched for studies published from inception to June, 2021. The primary endpoint was all-cause death, and the secondary endpoint was a composite of major adverse cardiac events (MACEs). Odds ratios (ORs) were pooled with 95% confidence intervals (CIs) for dichotomous data.Results: Seven studies involving 1540 participants were included in the final analysis. Pooled analyses revealed that patients with successful staged revascularization for CTO in non-IRA with STEMI treated with p-PCI had overall lower all-cause death compared with the occluded CTO group (OR, 0.46; 95% CI, 0.23‐0.95), cardiac death (OR, 0.43; 95% CI, 0.20‐0.91), MACEs (OR, 0.47; 95% CI, 0.32‐0.69) and heart failure (OR, 0.57; 95% CI, 0.37‐0.89) compared with the occluded CTO group. No significant differences were observed between groups regarding myocardial infarction and repeated revascularization.Conclusions: Successful revascularization of CTO in the non-IRA was associated with better outcomes in patients with STEMI treated with p-PCI.

Prevalence, Predictors, and Outcomes of Patients With ST-Elevation Myocardial Infarction and Angiographically Significant Coronary Artery Disease of Non-Infarct-Related Artery

Patients with ST-elevation myocardial infarction (STEMI) can present with angiographically significant coronary artery disease (CAD) of non-infarct-related artery (IRA) or with IRA-only CAD. This study aimed to evaluate the prevalence, predictors, and outcome of patients with STEMI and angiographically significant CAD of non-IRA. All consecutive patients with STEMI who underwent primary percutaneous coronary intervention between 2000 and 2020 were included. Angiographically significant CAD was defined as >50% stenosis of the left main coronary artery and/or >90% stenosis for all other coronary arteries. A total of 2,663 patients had IRA-only CAD (80.2%) and 657 had angiographically significant non-IRA CAD (19.8%). Independent predictors for non-IRA CAD were male gender (odds ratio [OR] 1.34, 95% confidence interval [CI] 1.05 to 1.70, p = 0.021), age >50 years (OR 1.45, 95% CI 1.11 to 1.91, p = 0.007), and diabetes mellitus (OR 1.56, 95% CI 1.29 to 1.9, p <0.001), whereas smoking (OR 0.83, 95% CI 0.68 to 0.99, p = 0.004) and family history of CAD (OR 0.78, 95% CI 0.62 to 0.98, p = 0.032) were found to be negatively associated with non-IRA CAD. In-hospital 30-day and 1- and 5-year all-cause mortality were higher in patients with non-IRA CAD compared with IRA-only CAD (5.8% vs 2.5%, 8.5% vs 3.3%, 18.4% vs 7.6% and 36.3% vs 20.3%, respectively; p for all <0.001). In conclusion, 20% of patients with STEMI had angiographically significant non-IRA CAD. Older age, male gender, and diabetes mellitus were independent predictors for non-IRA CAD, whereas smoking and family history of CAD predicted IRA-only CAD. The presence of non-IRA CAD was associated with higher short- and long-term all-cause mortality rates.

Clinical results after hybrid coronary revascularization with totally endoscopic coronary surgery

Background

The optimal revascularization strategy remains uncertain in multivessel coronary artery disease (MVCAD). The durability of the surgical grafts should be weighed against the decreased invasiveness of percutaneous coronary intervention (PCI). Hybrid coronary revascularization (HCR), a combination of PCI and surgery, could be a feasible alternative. This study aimed to investigate the occurrence of major adverse cardiac and cerebrovascular events (MACCE) and all-cause mortality after both endoscopic coronary artery bypass grafting (Endo-CABG) and the HCR procedure.

Methods

In this single-center retrospective observational study, 347 consecutive patients have been subjected to an Endo-CABG procedure, of which 103 underwent HCR between January 2016 and January 2018. A propensity score matching analysis was performed to match 103 Endo-CABG alone patients to the 103 HCR patients. The Endo-CABG procedure was performed through 3 endoscopic ports (5 mm) in the 2nd, 3rd, and 4th intercostal space and a utility port of 3 cm.

Results

In both the HCR and matched endo-CABG alone group, the 30-day mortality was acceptable (0% in the HCR group and 1.94% in the matched Endo-CABG alone group, p = 0.155). Additionally, the occurrence of MACCE after a mean follow-up of 1188 ± 538 days was similar in both groups (9.71% and 11.65% for the HCR and matched Endo-CABG alone group, respectively, p = 0.652). Still, the long-term all-cause mortality over this period was significantly higher in the matched Endo-CABG alone group (2.91% after the HCR procedure and 11.65% after matched Endo-CABG alone, p = 0.002).

Conclusion

HCR has some advantages over Endo-CABG alone regarding the all-cause mortality, cross-clamping time, intensive care unit, and hospital length of stay. Therefore, HCR may be a suitable alternative therapy for patients with MVCAD.

Predictors of residual coronary artery disease after PPCI in diabetic patients with STEMI

To describe the patients’ characteristics and risk factors of diabetic and non-diabetic patients presenting with ST-elevation myocardial infarction (STEMI) in relation to residual SYNTAX score after PPCI (primary PCI). Material and Method: Prospective observational study using data from all comers in NHI with STEMI and underwent PPCI over one month. Results: The present study consisted of 290 patients with ST-elevation myocardial infarction over one month period. About 50% of the patients with diabetes were more often female, with a greater prevalence of hypertension and dyslipidemia. In the diabetic group, the eGFR <60 ml/kg/min was associated with more residual CAD after PPCI and a higher residual SYNTAX score. Conclusion: eGFR is correlated with the presence of MVD in diabetic patients and with a higher residual syntax, which reflects the severity of disease in diabetic patients with nephropathy. That observation was not existing in a diabetic with normal eGFR or in non-diabetics with normal or reduced eGFR.

Systemic Vulnerability, as Expressed by I-CAM and MMP-9 at Presentation, Predicts One Year Outcomes in Patients with Acute Myocardial Infarction-Insights from the VIP Clinical Study

(1) Background: The prediction of recurrent events after acute myocardial infarction (AMI) does not sufficiently integrate systemic inflammation, coronary morphology or ventricular function in prediction algorithms. We aimed to evaluate the accuracy of inflammatory biomarkers, in association with angiographical and echocardiographic parameters, in predicting 1-year MACE after revascularized AMI. (2) Methods: This is an extension of a biomarker sub-study of the VIP trial (NCT03606330), in which 225 AMI patients underwent analysis of systemic vulnerability and were followed for 1 year. Hs-CRP, MMP-9, IL-6, I-CAM, V-CAM and E-selectin were determined at 1 h after revascularization. The primary end-point was the 1-year MACE rate. (3) Results: The MACE rate was 24.8% (n = 56). There were no significant differences between groups in regard to IL-6, V-CAM and E-selectin. The following inflammatory markers were significantly higher in MACE patients: hs-CRP (11.1 ± 13.8 vs. 5.1 ± 4.4 mg/L, p = 0.03), I-CAM (452 ± 283 vs. 220.5 ± 104.6, p = 0.0003) and MMP-9 (2255 ± 1226 vs. 1099 ± 706.1 ng/mL p = 0.0001). The most powerful predictor for MACE was MMP-9 of >1155 ng/mL (AUC-0.786, p < 0.001) even after adjustments for diabetes, LVEF, acute phase complications and other inflammatory biomarkers. For STEMI, the most powerful predictors for MACE included I-CAM > 239.7 ng/mL, V-CAM > 877.9 ng/mL and MMP-9 > 1393 ng/mL. (4) Conclusions: High levels of I-CAM and MMP-9 were the most powerful predictors for recurrent events after AMI for the overall study population. For STEMI subjects, the most important predictors included increased levels of I-CAM, V-CAM and MMP-9, while none of the analyzed parameters had proven to be predictive. Inflammatory biomarkers assayed during the acute phase of AMI presented a more powerful predictive capacity for MACE than the LVEF.

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.

Cardiac arrhythmias in the emergency settings of acute coronary syndrome and revascularization: an European Heart Rhythm Association (EHRA) consensus document, endorsed by the European Association of Percutaneous Cardiovascular Interventions (EAPCI), and European Acute Cardiovascular Care Association (ACCA)

Despite major therapeutic advances over the last decades, complex supraventricular and ventricular arrhythmias (VAs), particularly in the emergency setting or during revascularization for acute myocardial infarction (AMI), remain an important clinical problem. Although the incidence of VAs has declined in the hospital phase of acute coronary syndromes (ACS), mainly due to prompt revascularization and optimal medical therapy, still up to 6% patients with ACS develop ventricular tachycardia and/or ventricular fibrillation within the first hours of ACS symptoms. Despite sustained VAs being perceived predictors of worse in-hospital outcomes, specific associations between the type of VAs, arrhythmia timing, applied treatment strategies and long-term prognosis in AMI are vague. Atrial fibrillation (AF) is the most common supraventricular tachyarrhythmia that may be asymptomatic and/or may be associated with rapid haemodynamic deterioration requiring immediate treatment. It is estimated that over 20% AMI patients may have a history of AF, whereas the new-onset arrhythmia may occur in 5% patients with ST elevation myocardial infarction. Importantly, patients who were treated with primary percutaneous coronary intervention for AMI and developed AF have higher rates of adverse events and mortality compared with subjects free of arrhythmia. The scope of this position document is to cover the clinical implications and pharmacological/non-pharmacological management of arrhythmias in emergency presentations and during revascularization. Current evidence for clinical relevance of specific types of VAs complicating AMI in relation to arrhythmia timing has been discussed.

Risk Scoring System for Prognosis Estimation of Multivessel Disease Among Patients with ST-Segment Elevation Myocardial Infarction

Multivessel disease (MVD) is an independent risk factor for poor prognosis in acute myocardial infarction patients. Although several global risk scoring systems (RSS) are in use in clinical practice, there is no dedicated RSS for MVD in ST-segment elevation myocardial infarction (STEMI). The primary objective of this study is to develop a novel RSS to estimate the prognosis of patients with MVD in STEMI.We used the Korean Acute Myocardial Infarction Registry (KAMIR) to identify 2,030 STEMI patients with MVD who underwent appropriate percutaneous coronary intervention (PCI). Their data were analyzed to develop a new RSS. The prognostic power of this RSS was validated with 2,556 STEMI patients with MVD in the Korean Working Group on Myocardial Infarction Registry (KORMI).Six prognostic factors related to all-cause death in STEMI patients with MVD were age, serum creatinine, Killip Class, lower body weight, decrease in left ventricular ejection fraction, and history of cerebrovascular disease. The RSS for all-cause death was constructed using these risk factors and their statistical weight. The RSS had appropriate performance (c-index: 0.72) in the KORMI validation cohort.We developed a novel RSS that estimates all-cause death in the year following discharge for patients with MVD in STEMI appropriately treated by PCI. This novel RSS was transformed into a simple linear risk score to yield a simplified estimate prognosis of MVD among STEMI patients.

Chronic Total Occlusion Coronary Intervention: In Search of a Definitive Benefit

Percutaneous coronary intervention (PCI) of chronic coronary total occlusion is the latest frontier in percutaneous intervention. There are vast improvements in the initial success and safety of the procedure as well as a better understanding of appropriateness and benefits. Advances in technology and skill allow for increased utilization of PCI in cases of chronic coronary total occlusion, with benefits regarding symptoms and quality of life. Percutaneous coronary intervention for chronic coronary total occlusion can correct ischemia and achieve complete revascularization while avoiding traditional coronary bypass grafting, although survival benefits remain unclear.

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

Background

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

Method and Results

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

Conclusions

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

Robustness of Percutaneously Completed Coronary Revascularization in Stable Coronary Artery Disease: Obstructive Versus Occlusive Lesions

Our study sought to assess long-term outcomes of percutaneously completed coronary revascularization (CCR) in patients with obstructive coronary artery disease (CAD) comprising chronic total occlusions (CTOs). Between 2010 and 2014, percutaneous coronary interventions (PCIs) of the CTOs were attempted in 213 patients: the CCR was achieved in 125 patients (group 1), while the PCI failed in 88 patients (group 2). They were matched against 252 patients (group 3) with the CCR obtained by the non-CTO PCIs. In the 5-year follow-up, more adverse cardiovascular (CV) events occurred in group 2 (29.5% vs 4.8% in group 1 vs 3.5% in group 3, P = .0001), mainly due to recurrent severe symptoms and additional revascularization of the CTOs; CV mortality did not seem to be significantly affected. Survival curves for the successful CTO and non-CTO PCIs appeared indistinguishable. Stent thromboses were infrequent in the CCR groups. In conclusion, long-term outcomes of the patients with the obstructive CAD containing the CTOs showed a favorable outcome if the CCR had been achieved percutaneously.

Percutaneous Coronary Intervention of Chronic Total Occlusions in Patients With Low Left Ventricular Ejection Fraction

OBJECTIVES

The study sought to assess the outcome of percutaneous coronary intervention (PCI) of chronic total occlusions (CTOs) in patients with low left ventricular ejection fraction (LVEF) (≤35%).

BACKGROUND

Data regarding the outcome of PCI in patients with low LVEF affected by CTO are scarcely reported.

METHODS

The authors performed a prospective longitudinal multicenter study including consecutive patients undergoing elective PCI of CTOs. Patients were subdivided into 3 groups: group 1 (LVEF ≥50%), group 2 (LVEF 35% to 50%), and group 3 (LVEF ≤35%).

RESULTS

A total of 839 patients (mean 64.6 ± 10.5 years of age, 87.7% men) underwent CTO PCI attempts. Baseline LVEF ≤35% was present in 72 (8.6%) patients. The angiographic success was high (overall 93.6%) and similar among the 3 groups (93.5% vs. 94.4% vs. 91.7%, respectively; all p = NS). In group 3, no periprocedural complications of CTO PCI were observed. Mean clinical follow-up of 16.3 ± 8.2 months duration was available in 781 (93.1%) patients including those with LVEF ≤35%. At 2 years, major cardiac and cerebrovascular events (MACCE) free survival was similar in the 3 groups (86% vs. 82.8% vs. 75.2%; all p = NS). In patients with LVEF ≤35%, LVEF improved significantly in the presence of a successful CTO PCI from 29.1 ± 3.4% to 41.6 ± 7.9% (p < 0.001).

CONCLUSIONS

In CTO patients with low LVEF, PCI could represent a safe and effective revascularization strategy achieving good midterm outcome and LVEF improvement.

Prognostic value of the age, creatinine, and ejection fraction score for non-infarct-related chronic total occlusion revascularization after primary percutaneous intervention in acute ST-elevation myocardial infarction patients: A retrospective study

OBJECTIVE

It is not known if ACEF scores could evaluate the prognosis of recanalization of non-infarct-related coronary arteries (non-IRA) with chronic total occlusions (CTO) in patients who successfully underwent primary PCI. The objective of the current study was to assess the prognostic value of ACEF scores in acute ST-segment elevation myocardial infarction (STEMI) patients with non-IRA CTO after successful primary PCI.

METHODS

There were 2952 STEMI patients who underwent successful primary PCI from January 2006 to December 2014 in our hospital, among them 377 patients had a non-IRA CTO lesion. The patients were divided into successful CTO-PCI group (n = 221) and failed/non-attempted CTO-PCI group (n = 156). Patients were stratified based on the ACEF tertiles. Primary end points measured in the current study were major adverse cardiac events (MACE) defined as the composite of all-cause death, nonfatal myocardial infarction, ischemia-driven coronary revascularization and hospitalization for heart failure at 1 year.

RESULTS

The incidence of MACE, all-cause death and cardiac death were higher in the failed/non-attempted CTO-PCI group (P < 0.001). In the successful CTO-PCI group, the cumulative 1-year incidences of MACE and all-cause death were decreased compared to those in the failed/non-attempted CTO-PCI group (log-rank P < 0.001). The risk for MACE was reduced in the successful CTO-PCI group compared to the failed/non-attempted CTO-PCI group in patients with low and intermediate ACEF scores (log-rank P = 0.02).

CONCLUSIONS

Successfully staged CTO-PCI could gain advantageous clinical outcomes in those patients with low or intermediate ACEF scores.

Determinants of percutaneous coronary intervention success in repeat chronic total occlusion procedures following an initial failed attempt

AIM

To investigate the rates and determinants of success of repeat percutaneous coronary intervention (PCI) following an initial failed attempt at recanalising the chronic total occlusions (CTO) percutaneously.

METHODS

In 445 consecutive first attempt CTO-PCI procedures in our institution, procedural failure occurred in 149 (33.5%). Sixty-four re-PCI procedures were performed in 58 patients (39%) all had a single CTO. Procedural and outcome data in the re-PCI population was entered into the institutional database. A retrospective analysis of clinical, angiographic and procedural data was performed.

RESULTS

Procedural success was achieved in 41 (64%) procedures. Univariate analysis of clinical and angiographic characteristics showed that re-PCI success was associated with intravascular ultrasound (IVUS) guidance (19.5% vs 0%, P = 0.042), while failure was associated with severe calcification (30.4% vs 9.7%, P = 0.047) and a JCTO score > 3 (56.5% vs 17.1% P = 0.003). Following multiple regression analysis the degree of lesion complexity (J-CTO score > 3), IVUS use, involvement of an experienced CTO operator and LAD CTO location were significant predictors of successful re-PCI. Overall the complication rate was low, with the only MACCE two periprocedural MI’s neither of which required intervention.

CONCLUSION

Re-PCI substantially increases the overall success rate of CTO revascularization. Predictors of re-PCI success included the use of IVUS, the involvement of an experienced CTO operator in the repeat attempt and the location of the CTO.

Association of red cell distribution width with noninfarct-related artery-chronic total occlusion in acute myocardial infarction patients

Objective: The presence of chronic total occlusion (CTO) in noninfarct-related artery (non-IRA) is an independent predictor of mortality in acute myocardial infarction (AMI). We investigated whether red cell distribution width (RDW) levels are associated with presence of non-IRA-CTO in AMI (ST-elevation myocardial infarction [STEMI] and non-STEMI). Patients and methods: Patients (n = 858) were categorized into three groups: single vessel disease, multivessel disease (MVD) without CTO and MVD with CTO. Results: MVD with CTO group had higher RDW levels than single vessel disease and MVD without CTO groups (14.87 ± 1.09% vs 13.82 ± 1.01% and 13.87 ± 0.87%, respectively, p < 0.001). In-hospital mortality was also higher in patients with MVD with CTO (p < 0.001). On multivariate analysis, RDW (odds ratio [OR]: 1.761; p < 0.001), age (OR: 1.04; p < 0.001), creatinine (OR: 3.524; p = 0.027), current smoker (OR: 0.489; p = 0.022), hemoglobin (OR: 0.826; p = 0.044), and non-STEMI (OR: 3.065; p < 0.001) were predictors of occurrence of non-IRA-CTO. Conclusion: Increased RDW is independently associated with presence of non-IRA-CTO in AMI patients.

Defining the prognosis of chronic total occlusions during primary percutaneous coronary intervention

BACKGROUND

The influence of coexisting collateral circulation between chronic total occlusion (CTO) and infarct-related artery (IRA) in patients with acute ST segment elevation myocardial infarction (STEMI) remains unclear. We aimed to investigate the impact of coexisting collateral circulation between CTO and IRA on early clinical outcomes in patients with acute STEMI.

METHODS

A total of 1488 consecutive acute STEMI patients who underwent primary percutaneous coronary intervention were prospectively included in the study. After restoration of antegrade flow, the patients who had coexisting CTO and collateral supply from IRA were defined as the CTO-IRA-related (CIR) group (n=56). Patients with coexisting CTO but with no collateral supply from IRA were defined as the CTO-IRA-unrelated (CIUR) group (n=104). Patients without coexisting CTO were defined as the non-CTO group (n=1328).

RESULTS

Compared with the CIUR and non-CTO groups, the CIR group was significantly associated with higher Killip class of at least 2 (P<0.001) at presentation, a lower rate of postprocedural thrombolysis in myocardial infarction 2/3 flow (P<0.001), and myocardial perfusion grade 3 (P<0.001). Moreover, the CIR group had significantly higher in-hospital (P<0.001) and 30-day mortality (P<0.001). On multivariate regression analysis, the CIR group (odds ratio=15.96, 95% confidence interval=4.94-51.54; P<0.001) as well as age, post-PCI TIMI, Killip and NT-proBNP levels were independently associated with 30-day mortality. However, the CIUR group was not an independent predictor of early clinical outcomes.

CONCLUSION

After restoration of antegrade flow, coexisting CTO supplied by IRA collaterals has unfavourable effects on procedural success, enzymatic infarct size and postprocedural haemodynamic conditions. These collaterals are also independent predictors of 30-day mortality in acute STEMI patients.

Collateral filling efficiency of comorbid chronic total occlusion segment on short-term mortality in ST-elevation myocardial infarction

BACKGROUND

Collateral filling of chronic total occlusion (CTO) segments is considered to affect hemodynamic stability in primary percutaneous coronary intervention (PCI) for ST-elevation myocardial infarction (STEMI) with CTO, however its value as a prognostic indicator for mortality is uncertain. The present study examined the relationship between collateral filling of CTO segments and short-term mortality in patients with STEMI with a comorbid CTO lesion.

METHODS

Among 829 STEMI patients who underwent primary PCI, 74 patients with CTO were identified. Collateral filling of their CTO segment was assessed by Rentrop grade (0; n=10, 1; n=13, 2; n=31, 3; n=20) in their initial angiogram and whether the origin of the feeding collateral donor artery was infarct-related artery (IRA) was evaluated using their final angiogram in primary PCI; IRA (n=26) and non-IRA group (n=48). The relationship between these classifications and 30-day all-cause mortality was examined retrospectively.

RESULTS

The 30-day mortalities were 4.5% in single-vessel disease, 18.3% in multi-vessel disease (MVD) without CTO and 25.7% in MVD with CTO. Mortality of MVD with CTO reduced with increasing Rentrop grade from 0 to 3 (80.0%, 30.8%, 19.4%, and 5.0%, respectively). IRA was associated with a significant higher mortality than those of non-IRA (50.0% vs. 12.5%, P=0.0004). Low Rentrop grade 0 or 1 was extracted as an independent predictor of 30-day death (HR 3.28, 95% CI 1.20-9.96, P=0.0203).

CONCLUSIONS

Poor collateral filling of the CTO segment assessed by Rentrop grade was an independent angiographic predictor for 30-day death in patients with STEMI combined with CTO.

Chronic total coronary occlusion recanalization: Current techniques and new devices

Percutaneous coronary intervention (PCI) of total chronic coronary occlusion (CTO) still remains a major challenge. The prevalence of a CTO has been reported to be up to 30% among patients with a clinical indication for coronary angiography. Progress has been made with further advanced interventional techniques and continuously sophisticated interventional tools. Nevertheless the number of interventions carried out to recanalize a CTO is less than 10% of all procedures. Benefits of a successful CTO recanalization include relief of angina pectoris and ischemia-related dyspnea, substantial improvement in left ventricular function and, avoidance of surgery treatment. A vast variety of new CTO PCI techniques and materials has been introduced into clinical practise and pushed success rates of reopening a CTO up to around 90% in experienced hands. Particulary the introduction of the retrograde technique was a milestone. New developed microcatheters and special polymer coated wires allow to recanalize via small collaterals and vessels. Other tools such as intravascular ultrasound (IVUS) and multislice computertomography (MSCT) help to identify the anatomy and the characteristic of the lesions. Any invasive cardiac center should adopt CTO PCI procedures as standard therapy.

Objective

This review wants to assess and describe the latest development in CTO recanalization strategies.

Impact of the origin of the collateral feeding donor artery on short-term mortality in ST-elevation myocardial infarction with comorbid chronic total occlusion

BACKGROUND

Patients with ST-elevation myocardial infarction (STEMI) and multi-vessel disease (MVD) have higher mortality, especially with comorbid chronic total occlusion (CTO). The origin of collateral flow to the CTO segment has not been studied in regard to short-term mortality. This study examined the impact of collateral feeding donor arteries from an infarct-related artery (IRA) or non-IRA to the comorbid CTO segment in regard to STEMI short-term mortality.

METHODS

Data from 760 consecutive STEMI patients who underwent primary percutaneous coronary intervention were obtained retrospectively from medical records. The number of vessels involved and origin of the collateral feeding donor artery were evaluated using angiograms from the primary percutaneous coronary intervention. The study population was divided into patients with: single-vessel disease (SVD) (n=483), MVD without CTO (n=208), and MVD with CTO (n=64). All CTO segments had collateral flow from an IRA (n=23) or non-IRA (n=46). All-cause mortality (30-day) was analyzed.

RESULTS

Compared to SVD and MVD without CTO, MVD with comorbid CTO had a higher mortality (5.4% vs. 15.9% vs. 24.6%, P<0.0001, respectively). Of patients with CTO, those with collateral flow from the IRA had significantly higher mortality than the non-IRA group (52.2% vs. 10.9%, P<0.0001). Collateral flow from the IRA was extracted as an independent predictor associated with 30-day all-cause mortality using a multivariate Cox proportional hazards model (hazard ratio 4.71, 95% confidence interval 1.60-14.2, P=0.0005).

CONCLUSIONS

The origin of the collateral donor artery from the IRA had an impact on short-term mortality in STEMI patients with comorbid CTO lesions.

Impact of Chronic Total Occlusion in a Noninfarct-related Artery on Clinical Outcomes in Patients With Acute ST-elevation Myocardial Infarction Undergoing Primary Percutaneous Coronary Intervention

In the setting of primary percutaneous coronary intervention (PCI), encountering with chronic total occlusion (CTO) in a noninfarct-related artery (IRA) is not a rare situation. Limited information on the impact of CTO on clinical outcomes in acute ST-elevation myocardial infarction (STEMI) patients undergoing primary PCI has raised more concerns. The aim of the present study was to evaluate the effect of concurrent CTO in a non-IRA on the clinical outcomes in patients with STEMI undergoing primary PCI.In the present prospective study, 555 consecutive patients with STEMI who underwent early primary PCI from January 2010 to December 2013 were included. The patients were divided into 2 groups: no CTO and CTO. Data on 12 months follow-up was obtained from 449 patients. The primary endpoint was the composite of hospitalization from angina, reinfarction, heart failure, or re-revascularization, and cardiac death at 12 months follow-up.Of the 555 patients, 75 (13.5%) had CTO in a non-IRA. Compared with patients in no CTO group, more patients in CTO group had hypertension (62.7% vs 46.5%, P = 0.009), diabetes (49.3% vs 35.0%, P = 0.024), and 3-vessel disease (52.0% vs 32.3%, P = 0.001). Patients with CTO had a lower left ventricular ejection fraction (LVEF) (40.1% ± 16.8% vs 54.3% ± 12.1%, P = 0.038), more presented with cardiogenic shock on admission (13.3% vs 4.8%, P = 0.008), compared with patients without CTO. Complete revascularization (CR) was less achieved in CTO group than in no CTO group (33.3% vs 49.1%, P = 0.013). The 12-month cardiac mortality rate was 14.5% versus 6.2% (P = 0.039), the incidence of 12-month primary endpoint was 38.7% versus 21.2% (P = 0.003) for CTO and no CTO group, respectively. Multivariate analysis revealed that after correction for baseline differences, CTO in a non-IRA (hazard ratio 4.183, 95% confidence interval 1.940-6.019, P = 0.001), cardiogenic shock on admission (hazard ratio 3.286, 95% confidence interval 1.097-9.845, P = 0.034), and 3-vessel disease (hazard ratio 2.678, 95% confidence interval 1.221-5.874, P = 0.014) remained an independent predictor of 1-year cardiac mortality in patients with STEMI undergoing primary PCI.CTO in a non-IRA in patients with STEMI undergoing primary PCI is associated with a poor prognosis. The presence of CTO in a non-IRA, cardiogenic shock on admission and 3-vessel disease might be an independent risk factor for greater 1-year cardiac mortality in patients with acute STEMI undergoing primary PCI.

Training Standards and Recommendations for Intervention on Chronic Total Occlusions

Despite major advances in coronary intervention, the recanalization of a chronic total occlusion (CTO) remains a challenge for many interventional cardiologists. Complex anatomy and lesion characteristics demand a special set of skills for procedural success.

Provided patient selection is appropriate, CTO intervention can confer a variety of benefits including relief of angina, improvement in left ventricular function and reduction in ischemic burden. The chances of procedural success are enhanced by having a dedicated CTO program. This involves adequate training of staff, quality control and availability of equipment. A diverse toolkit allows variation in strategy and increases procedural success. Further, skills and equipment are required to manage complications like vessel dissection, perforation and the resultant ischemic or mechanical complications. These procedures can often be lengthy and giving careful consideration to peri-procedural issues like radiation exposure and contrast dose plays a vital role in ensuring optimal patient outcomes and radiation hygiene.

In this article we review the evidence behind indications for CTO intervention and discuss the development of a CTO program.

The evidence base for revascularisation of chronic total occlusions

When patients with ischaemic heart disease are considered for revascularisation the Heart Team's aim is to choose a therapy that will provide complete relief of angina for an acceptable procedural risk. Complete functional revascularisation of ischaemic myocardium is thus the goal and for this reason the presence of a chronic total occlusion (CTO) - which remain the most technically challenging lesions to revascularise percutaneously - is the most common reason for selecting coronary artery bypass surgery. From the behaviour of Heart Teams it is clear that physicians believe that CTOs are important. Yet when faced with patients with CTOs for whom surgery appears excessive (e.g. nonproximal LAD) or too high risk, there remains a reluctance to undertake CTO PCI, despite significant recent advances in procedural success and safety and a considerable body of evidence supporting a survival benefit following successful CTO PCI. This article reviews the relationship between CTOs, symptoms of angina, ischaemia and left ventricular dysfunction and further explores the evidence relating their treatment to improved quality of life and prognosis in patients with these features.

The role of coronary collaterals in chronic total occlusions

A chronic total occlusion (CTO) describes a completely occluded coronary artery. This type of lesion is found in about 18% of all significant lesions in patients with coronary artery disease. A system of collateral connections are observed in almost all of these lesions, which have the capacity to prevent myocardial necrosis and may even uphold metabolic supply to the territory distal to an occlusion to maintain full contractile capacity. During exercise these collaterals are limited in their functional reserve, and more than 90% of patients with a well collateralized occlusion will experience ischemia. in the absence of ideal animal models that mimic the human collateral circulation, we need to rely on studies in man. The knowledge of collateral physiology in man has increased considerably over the past two decades with the advent of intracoronary sensors of coronary pressure and flow velocity. A number of basic physiologic questions have been answered by these studies. The blood supply through coronary arteries depends on a complex array of in general serial resistance systems, with an additional array of multiple parallel resistances on the collateral level. There seems to be a great interindividual variability in the ability to recruit preformed collateral connections in the case of an epicardial occlusion. Collateral function can develop to a similar functional level in patients post myocardial infarction with large akinetic territories as it does in patients with normal preserved regional function. The presence of viability is thus not a prerequisite for collateral development. The question of practical relevance in the era of interventional therapy of chronic occlusions is also, whether a patient with coronary artery disease will remain protected by collaterals after removing the obstruction in the collateralized artery, or whether collaterals regress and lose their functional capacity. Both developments are observed again mainly depending of individual predisposition.

Chronic total occlusions - Current techniques and future directions

Chronic total occlusions (CTOs) of coronary arteries represent a common and significant challenge to interventional cardiology. Medical therapy is often regarded as an adequate long term strategy in the management of these lesions with surgical intervention for refractory symptoms. Extensive collateralisation is used as a marker of distal coronary perfusion, further reinforcing non-invasive strategies. This together with relatively low percutaneous success rates outside of specialised centres has meant that rates of percutaneous intervention have remained low. Increasing evidence suggests that CTOs are not a benign entity. Further, symptom control and quality of life improve significantly with successful percutaneous revascularisation. Both factors have reignited interest in percutaneous modalities. The Japanese have been pioneers in the field of CTO intervention although their success rates have been difficult to replicate. New techniques and equipment developed in North America offer an alternative to the Japanese approach. These techniques focus on time, radiation and contrast minimisation. This review will assess the histopathology of CTO and shifting paradigms in CTO treatment strategies.

•

Chronic total occlusions are common and prognostically important.

•

Strategies for chronic occlusions are pioneered by Japanese, adapted by North American operators.

•

Japanese and North American strategies appear divergent, both add considerable expertise.