The role of coronary collaterals in chronic total occlusions

PET evaluation of myocardial perfusion function after percutaneous coronary intervention in patients with chronic total occlusion: a systematic review and meta-analysis

Objective. The benefit of percutaneous coronary intervention (PCI) in chronic complete coronary artery occlusion (CTO) remains controversial. PCI is currently indicated only for symptom and myocardial ischemia abolition, but large chronically occluded vessels with extensive afferent myocardial territories may benefit most from this procedure. The noninvasive evaluation of myocardial perfusion is critical before and after revascularization, and positron emission tomography (PET) can determine absolute myocardial perfusion. Here, we aimed to explore and compare myocardial perfusion in CTO territories and their remote associated areas before and after PCI. Design. We searched for relevant articles published before November 28, 2022, in the Cochrane Library and PubMed. We calculated 95% confidence intervals (CIs) and standardized mean differences (SMDs) for parameters related to myocardial perfusion in CTO territories and remote areas in CTO patients before and after PCI. Results. We included five studies published between 2017 and 2022, with a total of 592 patients. Stress myocardial blood flow (MBF) was increased in CTO territories after PCI when compared to pre-PCI (mean difference [MD]: 1.70, 95% confidence interval [CI] 1.33-2.08, p < 0.001). Coronary flow reserve (CFR) in CTO regions was also higher after PCI (MD 1.37,95% [CI]1.13-1.61, p < 0.001). Stress MBF in remote regions was also increased after PCI (MD 0.27,95% [CI]0.99 ∼ 0.45, p = 0.004), as was CFR in remote regions (MD 0.32,95% [CI] 0.14-0.5, p = 0.001). Conclusions. According to our pooled analysis of current literature, there was an increase in stress MBF and CFR in both CTOs and remote regions after PCI, suggesting that patients with CTO have widespread recovery of blood perfusion after the procedure. These results provide evidence that patients with CTO arteries and high ischemic burdens would indeed benefit from CTO-PCI. Future research on the correlation of ischemia burden reduction with hard clinical endpoints would contribute to a clearer demarcation of the role of CTO PCI with prognostic potential.

Review of cardiac-coronary interaction and insights from mathematical modeling

Cardiac-coronary interaction is fundamental to the function of the heart. As one of the highest metabolic organs in the body, the cardiac oxygen demand is met by blood perfusion through the coronary vasculature. The coronary vasculature is largely embedded within the myocardial tissue which is continually contracting and hence squeezing the blood vessels. The myocardium-coronary vessel interaction is two-ways and complex. Here, we review the different types of cardiac-coronary interactions with a focus on insights gained from mathematical models. Specifically, we will consider the following: (1) myocardial-vessel mechanical interaction; (2) metabolic-flow interaction and regulation; (3) perfusion-contraction matching, and (4) chronic interactions between the myocardium and coronary vasculature. We also provide a discussion of the relevant experimental and clinical studies of different types of cardiac-coronary interactions. Finally, we highlight knowledge gaps, key challenges, and limitations of existing mathematical models along with future research directions to understand the unique myocardium-coronary coupling in the heart. This article is categorized under: Cardiovascular Diseases > Computational Models Cardiovascular Diseases > Biomedical Engineering Cardiovascular Diseases > Molecular and Cellular Physiology.

Basic Overview of Conventional Coronary Angiography for Planning Cardiac Surgery

Coronary angiography is a common procedure performed by the cardiologist to evaluate coronary atherosclerotic disease (CAD) and the result is utilized by both cardiologists and cardiac surgeons to perform catheter and surgical interventions on the coronary artery. In addition to evaluating CAD, other useful investigative modalities such as left ventriculography and aortography can be performed at the time of coronary angiography. Despite its limitations and the emergence of newer investigative modalities like coronary computed tomography angiography, intravascular ultrasound scan, and magnetic resonance coronary angiography, conventional coronary angiography has remained the gold standard for the evaluation of coronary artery disease. Hence, it remains an investigative modality that every member of the cardiothoracic team performing coronary artery bypass grafting must learn how to interpret.

Uric acid to high-density lipoprotein cholesterol ratio predicts adverse cardiovascular events in patients with coronary chronic total occlusion

BACKGROUND AND AIMS

Uric acid to high-density lipoprotein cholesterol ratio (UHR) is a novel index of metabolism and inflammation proposed by recent studies. The prognostic value of UHR is undetermined in patients with coronary chronic total occlusion (CTO). The aim of this study was to investigate the association of UHR with adverse cardiovascular events in patients with CTO.

METHODS AND RESULTS

In this retrospective cohort study, we enrolled 566 patients with CTO lesion in our hospital from January 2016 to December 2019. Patients were divided into three groups based on UHR level. The primary endpoint was major adverse cardiovascular event (MACE), defined as a combination of death, non-fatal MI, target vessel revascularization (TVR), and non-fatal stroke. The median follow-up time of this study was 43 months. During the follow-up, 107 (18.9%) MACEs were recorded. Kaplan-Meier survival plots show the cumulative incidence of MACE-free decreased across tertile of UHR (log-rank test, p < 0.001). In the fully adjusted model, the Hazard ratio (95% CI) of MACE was 2.16 (1.17-3.99) in tertile 3 and 2.01 (1.62-2.49) for per SD increase in UHR.

CONCLUSION

Elevated UHR predicts an increasing risk of MACE in patients with CTO. UHR is a simple and reliable indicator for risk stratification and early intervention in CTO patients.

Role of percutaneous coronary intervention in the modern-day management of chronic coronary syndrome

Contemporary randomised trials of percutaneous coronary intervention (PCI) in chronic coronary syndrome (CCS) demonstrate no difference between patients treated with a conservative or invasive strategy with respect to all-cause mortality or myocardial infarction, although trials lack power to test for individual endpoints and long-term follow-up data are needed. Open-label trials consistently show greater improvement in symptoms and quality of life among patients with stable angina treated with PCI. Further studies are awaited to clarify this finding. In patients with severe left ventricular (LV) systolic dysfunction and obstructive coronary artery disease in the Revascularization for Ischemic Ventricular Dysfunction trial, PCI has not been found to improve all-cause mortality, heart failure hospitalisation or recovery of LV function when compared with medical therapy. PCI was, however, performed without additional hazard and so remains a treatment option when there are favourable patient characteristics. The majority of patients reported no angina, and the low burden of angina in many of the randomised PCI trials is a widely cited limitation. Despite contentious evidence, elective PCI for CCS continues to play a significant role in UK clinical practice. While PCI for urgent indications has more than doubled since 2006, the rate of elective PCI remains unchanged. PCI remains an important strategy when symptoms are not well controlled, and we should maximise its value with appropriate patient selection. In this review, we provide a framework to assist in critical interpretation of findings from most recent trials and meta-analysis evidence.

Changes in absolute flow, myocardial resistance and FFR after chronic total occlusion percutaneous coronary intervention

BACKGROUND

Randomised studies of percutaneous coronary intervention (PCI) in patients with chronic total occlusion (CTO) have shown inconsistent outcomes, suggesting incomplete understanding of this cohort and their coronary physiology. To address this shortcoming, we designed a prospective observational study to measure the recovery of absolute coronary blood flow following successful CTO PCI Aims: We sought to identify patient and procedural characteristics associated with a favourable physiological outcome after CTO PCI.

METHODS

Consecutive patients with a CTO subtending viable myocardium underwent PCI utilising contemporary techniques and the hybrid algorithm. Immediately after PCI, and at 3-month follow-up, physiological measurements were performed utilising continuous thermodilution.

RESULTS

A total of 81 patients were included with a mean age of 63.6±8.9 years, and 66 (81.5%) were male. Physiological measurements of absolute coronary blood flow in the CTO vessel increased by 30% (p<0.001) and microvascular resistance reduced by 16% (p<0.001) from immediately post-CTO PCI to follow-up assessment. Fractional flow reserve increased by 0.02 (p=0.015) in the same period. Prior coronary artery bypass graft (CABG) and a higher estimated glomerular filtration rate (eGFR) were associated with a larger change in absolute flow. An extraplaque strategy was associated with a smaller change in absolute flow.

CONCLUSIONS

Post-CTO PCI, there is a continued augmentation in absolute coronary blood flow and reduction in microvascular resistance from baseline to follow-up at 3 months. Prior CABG and a higher baseline eGFR were predictors of a larger change in absolute coronary flow, whilst an extraplaque final wire path strategy predicted a smaller change. Lastly, the patient characteristics and comorbidities had a larger influence than procedural factors on the observed change in absolute flow.

Infarct-Related Artery as a Donor of Collaterals in ST-Segment-Elevation Myocardial Infarction With Concomitant Chronic Total Occlusion: Challenge of the Double-Jeopardy Thesis

BACKGROUND In ST-segment-elevation myocardial infarction (STEMI), a concomitant chronic total occlusion (CTO) in a non-infarct-related artery (NIRA) is associated with adverse outcome. In the case of the infarct-related artery (IRA) as a donor vessel for collaterals to the CTO, the IRA occlusion may lead to an acute threat to both the immediate IRA and the collaterally supplied CTO area, which has been described as a double-jeopardy effect. METHODS AND RESULTS We investigated the role of preformed intercoronary collaterals to the CTO originating from either the IRA or NIRA. Data were obtained from 2 hospitals participating in the prospective FITT-STEMI (Feedback Intervention and Treatment Times in ST-Segment Elevation Myocardial Infarction) study. From a total cohort of 2102 patients with acute STEMI, 93 patients had single-vessel CTO in an NIRA and well-developed intercoronary collaterals to the CTO. In-hospital mortality differed significantly with respect to the origin of the collaterals. Mortality was 15.2% with collaterals originating from the NIRA, 29.4% with a collateral origin from the IRA proximal to the acute STEMI occlusion, and 3.3% with a collateral origin from the IRA distal to the acute occlusion (P=0.044). A multivariate regression model confirmed that a proximal collateral origin had a significant higher mortality compared with a branching in the distal position from the acute STEMI occlusion (P=0.027; odds ratio = 20.8 [95% CI, 1.4-304.1]). CONCLUSIONS In STEMI with CTO in an NIRA, a CTO collateralization from the IRA distal to the acute occlusion is associated with a better prognosis. This finding challenges the double-jeopardy assumption as the main cause of adverse outcome in STEMI with CTO in an NIRA. REGISTRATION URL: https://www.clinicaltrials.gov; Unique identifier: NCT00794001.

Percutaneous coronary intervention improves quality of life of patients with chronic total occlusion and low estimated glomerular filtration rate

Background

A low estimated glomerular filtration rate (eGFR <90 mL/min/1.73 m²) is widely recognized as a risk factor for major adverse cardiac events (MACE) after percutaneous coronary intervention (PCI) for chronic total occlusion (CTO). However, the impact of successful CTO-PCI on quality of life (QOL) of patients with low eGFR remains unknown.

Objectives

The aim of this prospective study was to assess the QOL of CTO patients with low eGFR after successful PCI.

Methods

Consecutive patients undergoing elective CTO-PCI were prospectively enrolled and subdivided into four groups: eGFR ≥90 mL/min/1.73 m² (n = 410), 90 > eGFR ≥ 60 mL/min/1.73 m² (n = 482), 60 > eGFR ≥ 30 mL/min/1.73 m² (n = 161), and eGFR <30 mL/min/1.73 m² (n = 23). The primary outcomes included QOL, as assessed with the European Quality of Life-5 Dimensions (EQ-5D) questionnaire, and symptoms, as assessed with the Rose Dyspnea Scale (RDS) and Seattle Angina Questionnaire (SAQ), at 1 month and 1 year after successful PCI.

Results

With the decline of eGFR, CTO patients were more likely to present with comorbidities of hypertension, diabetes, hyperuricemia, and previous stroke, in addition to lower hemoglobin levels and left ventricular ejection fraction (p < 0.05). Low eGFR was associated with greater incidences of in-hospital pericardiocentesis, major bleeding, acute renal failure, and subcutaneous hematoma, but not in-hospital MACE (p < 0.05). Symptoms of dyspnea and angina were alleviated in all CTO patients with eGFR ≥30 mL/min/1.73 m² at 1 month and 1 year after successful CTO-PCI, but only at 1 month for those with eGFR <30 mL/min/1.73 m² (p < 0.01). Importantly, QOL was markedly improved at 1 month and 1 year after successful PCI (p < 0.01), notably at a similar degree between patients with low eGFR and those with normal eGFR (p > 0.05).

Conclusion

Successful PCI effectively improved symptoms and QOL of CTO patients with low eGFR.

Case Report: Endovascular Treatment of Chronic Atherosclerotic Renal Artery Total Occlusions with Failed Medical Therapy

Background

Current guidelines generally no longer support revascularization for chronic renal artery occlusive diseases because results from randomized controlled trials favor medical therapy over angioplasty. However, increasing reports indicate that patients with renal artery occlusion (RAO) can benefit from revascularization under certain circumstances.

Case summary

Here, we present a patient with renal artery stenosis (RAS) who does not have refractory hypertension or fit any clinical trial inclusion criteria by far. Medical therapy failed to prevent the progression of RAS in this patient, leading to total occlusion of his right renal artery. This patient had progressive renal insufficiency but recovered renal function after endovascular treatment.

Conclusion

This case demonstrates that angioplasty can be beneficial in selected RAO patients, especially those with residual renal function and collateral perfusion.

Early recruitable coronary collaterals preserve miocardial viability in late presentation infarctions

BACKGROUND

Previous studies showed conflicting results regarding the contribution of coronary collateral circulation (CCC) to myocardial perfusion and function in the setting of myocardial infarction (MI). In the primary angioplasty era, the role of CCC in these studies may have been influenced by the effect of early reperfusion. The true impact of CCC could be clarified by studying its effect on nonreperfused patients. The aim of our study was to evaluate the effect of CCC on myocardial viability of late presentation MI.

METHODS AND RESULTS

Between 2008 and 2019, we included 167 patients with a late presentation MI who had a complete angiographic occlusion in a major coronary artery in which myocardial viability of the culprit territory was assessed. Patients were divided according to the presence of angiographic early recruited CCC (ERCC) (Rentrop 2-3) or poor CCC (PCC) (Rentrop 0-1). A lower left ventricular ejection function (LVEF) at discharge (54.2 ± 9 vs. 47.9 ± 12; <0.01) and a more severe left ventricular wall motion abnormalities in the culprit territory were observed in PCC patients. The presence of ERCC was the main independent predictor of myocardial viability in late presentation MI (hazard ratio, 4.24; 95% confidence interval, 1.68-10.6; P < 0.001). At follow-up, wall motion score increased significantly (2.05 ± 0.16; P = 0.02) in patients with ERCC but not in PCC patients (0.07 ± 0.16; P = 0.4), and LVEF improvement was significantly higher in ERCC than in PCC patients (9.7 ± 2.6 vs. 3.8 ± 4.2; P = 0.02).

CONCLUSION

The presence of ERCC was the main independent predictor of myocardial viability in late presentation MI.

Diagnostic and Management Strategies in Patients with Late Recurrent Angina after Coronary Artery Bypass Grafting

Purpose of Review

This review will outline the current evidence on the anatomical, functional, and physiological tools that may be applied in the evaluation of patients with late recurrent angina after coronary artery bypass grafting (CABG). Furthermore, we discuss management strategies and propose an algorithm to guide decision-making for this complex patient population.

Recent Findings

Patients with prior CABG often present with late recurrent angina as a result of bypass graft failure and progression of native coronary artery disease (CAD). These patients are generally older, have a higher prevalence of comorbidities, and more complex atherosclerotic lesion morphology compared to CABG-naïve patients. In addition, guideline recommendations are based on studies in which post-CABG patients have been largely excluded.

Summary

Several invasive and non-invasive diagnostic tools are currently available to assess graft patency, the hemodynamic significance of native CAD progression, left ventricular function, and myocardial viability. Such tools, in particular the latest generation coronary computed tomography angiography, are part of a systematic diagnostic work-up to guide optimal repeat revascularization strategy in patients presenting with late recurrent angina after CABG.

Impact of percutaneous coronary intervention of chronic total occlusions on absolute perfusion in remote myocardium

BACKGROUND

Revascularisation of a chronic total coronary occlusion (CTO) impacts the coronary physiology of the remote myocardial territory.

AIMS

This study aimed to evaluate the intrinsic effect of CTO percutaneous coronary intervention (PCI) on changes in absolute perfusion in remote myocardium.

METHODS

A total of 164 patients who underwent serial [¹⁵O]H_²O positron emission tomography (PET) perfusion imaging at baseline and three months after successful single-vessel CTO PCI were included to evaluate changes in hyperaemic myocardial blood flow (hMBF) and coronary flow reserve (CFR) in the remote myocardium supplied by both non-target coronary arteries.

RESULTS

Perfusion indices in CTO and remote myocardium showed a positive correlation before (resting MBF: r=0.84, hMBF: r=0.75, and CFR: r=0.77, p<0.01 for all) and after (resting MBF: r=0.87, hMBF: r=0.87, and CFR: r=0.81, p<0.01 for all) CTO PCI. Absolute increases in hMBF and CFR were observed in remote myocardium following CTO revascularisation (from 2.29±0.67 to 2.48±0.75 mL·min^-1·g^-1 and from 2.48±0.76 to 2.74±0.85, respectively, p<0.01 for both). Improvements in remote myocardial perfusion were largest in patients with a higher increase in hMBF (β 0.58, 95% CI: 0.48-0.67, p<0.01) and CFR (β 0.54, 95% CI: 0.44-0.64, p<0.01) in the CTO territory, independent of clinical, angiographic and procedural characteristics.

CONCLUSIONS

CTO revascularisation resulted in an increase in remote myocardial perfusion. Furthermore, the quantitative improvement in hMBF and CFR in the CTO territory was independently associated with the absolute perfusion increase in remote myocardial regions. As such, CTO PCI may have a favourable physiologic impact beyond the intended treated myocardium.

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

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

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

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

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

Correlation of serum Vascular Endothelial growth factor (VEGF) and cardiovascular risk factors on collateral formation in patients with acute coronary artery syndrome

Coronary collaterals serve as an alternative source of blood flow in obstructive coronary heart disease. Coronary collateral development by releasing various angiogenic growth factors, including vascular endothelial growth factor-A (VEGF-A). Cardiovascular risk factors strongly associated with coronary artery disease include age, sex, elevated serum cholesterol, disturbed carbohydrate metabolism, and elevated blood pressure. A better understanding of the effects of these cardiovascular risk factors and serum VEGF-A level on collateral recruitment is necessary for a better prognosis in coronary artery diseases and new insight for further therapeutic promotion of coronary collaterals.220 consecutive patients undergoing coronary angiography with a mean age of 61 ± 9.83 were selected for the analysis. Two millilitres of blood were taken from the patients for analysis. The blood serum VEGF concentration was quantified via the ELISA method. Angiograms and other clinical reports were collected. Significant coronary artery disease was diagnosed in those with ≥ 70% of stenosis in at least one of the coronary arteries. The angiographic and clinical data were documented. The collateral grading was done according to the Rentrop Scoring system. The serum vascular endothelial growth factor level was correlated with the collateral score and cardiovascular risk factors like age, sex, type ll diabetes, blood pressure, and cholesterol level. An increase in the level of the collateral score was noted with an increase in the level of VEGF in blood serum. A significant association was founded between serum VEGF level and cardiovascular risk factors on collateral formation in patients with diabetes and hypertension. This article is protected by copyright. All rights reserved.

Non-high-density lipoprotein cholesterol/high-density lipoprotein cholesterol ratio serve as a predictor for coronary collateral circulation in chronic total occlusive patients

Objective

The present study investigated the potential correlation between non-high-density lipoprotein cholesterol/high-density lipoprotein cholesterol ratio (non-HDL-C/HDL) and the formation of coronary collateral circulation (CCC) in coronary artery disease cases with chronic total occlusive (CTO) lesions.

Methods

Two experienced cardiologists identified and selected patients with CTO lesions for retrospective analysis. The 353 patients were divided into a CCC poor formation group (Rentrop 0–1 grade, n = 209) and a CCC good formation group (Rentrop 2–3 grade, n = 144) based on the Cohen-Rentrop standard. A comparison of non-HDL-C/HDL ratios between the two groups was performed. The Spearman test was used to obtain the correlation between the cholesterol ratio and Rentrop grade. Independent predictors of CCC were analyzed using logistic regression. Receiver operating characteristic (ROC) curve analysis was also performed to quantify the predictive value of research indicator.

Results

The non-HDL-C/HDL ratio in the CCC poor formation group was elevated markedly compared to the CCC good formation group [( 3.86 ± 1.40) vs ( 3.31 ± 1.22), P = 0.000]. The Spearman test results indicated that non-HDL-C/HDL negatively correlated with Rentrop grade (r = − 0.115, P = 0.030). Multivariate logistic regression analysis showed that non-HDL-C/HDL ratio was an independent predictor of CCC formation (OR = 1.195, 95%CI = 1.020–1.400, P = 0.027). The area under the curve of ROC for detecting CCC poor formation was 0.611 (95% CI: 0.551–0.671, P = 0.000) with an optimal cut-off value of 2.77.

Conclusion

Non-HDL-C/HDL negatively correlated with the formation of CCC and served as an independent predictor of CCC formation, which may be used as a biomarker for the evaluation of CCC.

Contradictory Effect of Coronary Collateral Circulation on Regional Myocardial Perfusion That Assessed by Quantitative Myocardial Perfusion Scintigraphy

Background

Previous studies showed conflicting results about the contribution of coronary collateral circulation (CCC) to myocardial perfusion and function. The aim of this study was to investigate these contradictory problems by gated myocardial perfusion scintigraphy (gated MPS) for the first time.

Methods

The current cohort was retrospectively selected among patients who underwent gated MPS and coronary angiography within 2 months. Two different groups including 96 patients were assessed by gated MPS to detect the understanding of the miscellaneous effect of CCC on myocardial perfusion. Group 1 consisted of those who had collateral arteries that were not-well-developed (Rentrop grade 0 - 1) (n = 58), while group 2 consisted of those who had collateral arteries that were well-developed (Rentrop grade 2 - 3) (n = 38).

Results

There was no statistically significant difference between groups 1 and 2 in terms of perfusion and functional parameters obtained from gated MPS. Furthermore, no statistically significant difference was found in the phase analysis parameters which is a novel technique to evaluate left ventricular synchronization. On the other hand the left ventricular mass index values were high and quite close to the statistically significant value (P = 0.059) in group 2.

Conclusions

The current results that obtained by using the gated MPS technique for the first time in the evaluation of CCC showed that the well-developed collateral circulation has a positive effect on myocardial perfusion and function, but this effect was not statistically significant. Results need to be supported by large scale of patients’ size.

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.

A preoperative modified Allen test result may be associated with long term mortality after hemodialysis access construction

BACKGROUND

The modified Allen test (MAT) is a simple bedside method determining collateral hand circulation prior to hemodialysis (HD) access surgery. Hand ischemia as reflected by low systolic finger pressures (P_dig) is associated with high mortality rates in severe kidney disease (CKD) patients. Aim of the present study was to assess a possible relation between absolute finger pressure drop (∂P_dig) during a preoperative MAT and mortality after a first HD access construction.

METHODS

P_dig (systolic pressure, mmHg) was measured using digital plethysmography following compression of radial and ulnar arteries in CKD patients just before access surgery between January 2009 and December 2018 in one center. The greatest ∂P_dig of both index fingers was used for analysis. Cardiovascular and overall mortality were assessed during the following 4 years using the ERA-EDTA classification system (codes 11, 14-16, 18, 22-26, 29). Cox regression analysis determined possible associations between ∂P_dig and mortality.

RESULTS

Complete data sets were available in 108 patients (male n = 71; age 70 years ±12; mean follow up (FU) 1.6 years ±0.1; FU index 99% ±1). Median ∂P_dig was 31 mmHg (range 0-167 mmHg). Patients having cardiovascular disease (CV+) demonstrated higher ∂P_dig values (CV+ 44 ± 5 mmHg vs CV- 29 ± 3 mmHg, p = 0.012). A total of 26 patients (24%) died during FU (CV+ death, n = 16; 62%). For each 10 mmHg ∂P_dig increase, overall mortality increased by 10%, and CV+ mortality by 15% (overall mortality: HR 1.10 [1.01-1.22], p = 0.048; CV+ mortality: 1.15 [1.03-1.29], p = 0.017). Following correction for age, ∂P_dig remained associated with CV+ mortality (HR 1.13 [1.00-1.26], p = 0.043).

CONCLUSIONS

A large drop in systolic finger pressure during a preoperative MAT is related to mortality after primary HD access surgery. The role of this potential novel risk parameter requires confirmation in a larger population.

Vulnerability for ventricular arrhythmias in patients with chronic coronary total occlusion

INTRODUCTION

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

AREAS COVERED

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

EXPERT OPINION

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

Prompt and consistent improvement of coronary flow velocity reserve following successful recanalization of the coronary chronic total occlusion in patients with viable myocardium

Background

Coronary chronic total occlusion (CTO) is characterized by the presence of collateral blood vessels which can provide additional blood supply to CTO-artery dependent myocardium. Successful CTO recanalization is followed by significant decrease in collateral donor artery blood flow and collateral derecruitment, but data on coronary hemodynamic changes in relation to myocardial function are limited. We assessed changes in coronary flow velocity reserve (CFVR) by echocardiography in collateral donor and recanalized artery following successful opening of coronary CTO.

Methods

Our study enrolled 31 patients (60 ± 9 years; 22 male) with CTO and viable myocardium by SPECT scheduled for percutaneous coronary intervention (PCI). Non-invasive CFVR was measured in collateral donor artery before PCI, 24 h and 6 months post-PCI, and 24 h and 6 months in recanalized artery following successful PCI of CTO.

Results

Collateral donor artery showed significant increase in CFVR 24 h after CTO recanalization compared to pre-PCI values (2.30 ± 0.49 vs. 2.71 ± 0.45, p = 0.005), which remained unchanged after 6-months (2.68 ± 0.24). Baseline blood flow velocity of the collateral donor artery significantly decreased 24 h post-PCI compared to pre-PCI (0.28 ± 0.06 vs. 0.24 ± 0.04 m/s), and remained similar after 6 months, with no significant difference in maximum hyperemic blood flow velocity pre-PCI, 24 h and 6 months post-PCI. CFVR of the recanalized coronary artery 24 h post-PCI was 2.55 ± 0.35, and remained similar 6 months later (2.62 ± 0.26, p = NS).

Conclusions

In patients with viable myocardium, prompt and significant CFVR increase in both recanalized and collateral donor artery, was observed within 24 h after successful recanalization of CTO artery, which maintained constant during the 6 months.

Trial registration

ClinicalTrials.gov (Number NCT04060615).

Impact of coronary collateralization on long-term clinical outcomes in type 2 diabetic patients after successful recanalization of chronic total occlusion

Background

To assess the prognostic role of coronary collaterals in patients with type 2 diabetes mellitus (T2DM) after successful percutaneous coronary intervention (PCI) for chronic total occlusion (CTO).

Methods

Coronary collateralization was graded according to Rentrop scoring system in 198 type 2 diabetic patients and 335 non-diabetics with stable angina undergoing PCI for at least one CTO lesion. Left ventricular ejection fraction (LVEF) was determined and major adverse cardio-cerebral events (MACCE) were recorded during follow-up.

Results

Poor collateralization was more common in patients with T2DM than in non-diabetics (40% vs 29%, p = 0.008). At 13.5 ± 4.1 months, the rate of composite MACCE (17.3% vs 27.6%, p = 0.034) and repeat revascularization (15.2% vs 25.5%, p = 0.026) was lower and the increase in LVEF (3.10% vs 1.80%, p = 0.024) was greater in patients with good collaterals than in those with poor collaterals for non-diabetic group. The associations were in the same direction for T2DM group (35% vs 44%; 30% vs 36%; 2.14% vs 1.65%, respectively) with a higher all-cause mortality in diabetic patients with poor collaterals (p = 0.034). Multivariable Cox proportional hazards analysis showed that coronary collateralization was an independent factor for time to MACCE (HR 2.155,95% CI 1.290–3.599, p = 0.003) and repeat revascularization (HR 2.326, 95% CI 1.357–3.986, p = 0.002) in non-diabetic patients, but did not enter the model in those with T2DM.

Conclusions

T2DM is associated with reduced coronary collateralization. The effects of the status of coronary collateralization on long-term clinical outcomes and left ventricular function appear to be similar in size in type 2 diabetic patients and non-diabetics after successful recanalization of CTO.

LncRNA-LUNAR1 Levels Are Closely Related to Coronary Collaterals in Patients with Chronic Total Coronary Occlusion

Coronary collaterals can effectively improve myocardial blood supply to the area of CTO (chronic total coronary occlusion) and can, thus, reduce infarct size. LUNAR1(leukemia-induced noncoding activator RNA-1) is a specific LncRNA regulated by Notch signaling that not only can enhance the expression of IGFR-1 but also can promote angiogenesis and cell survival. Here, we investigated the relationship between LncRNA-LUNAR1 levels in peripheral plasma and the formation of coronary collaterals. In total, 172 patients with CTO were enrolled and followed up for 12 months. Coronary collaterals were scored according to the Rentrop scoring system. Preclinical tests of tube formation were used to address the mechanisms behind the association between LncRNA-LUNAR1 and development of collaterals. Clinical data and inflammatory factors, including comorbidity, CD14⁺⁺CD16^- monocytes, and CCL2 (chemokine motif ligand 2), were compared and analyzed. Real-time PCR was used to detect the expression of LncRNA-LUNAR1 in peripheral blood plasma. The Rentrop score was positively correlated with LncRNA-LUNAR1 levels in patients with CTO (R = 0.47, p < 0.001). Tube formation assay proved the direct association between LncRNA-LUNAR1 and development of collaterals (p = 0.011). The univariate Kaplan-Meier analysis revealed that patients with low LncRNA-LUNAR1 expression exhibited worse clinical outcomes than those with high LncRNA-LUNAR1 levels (p = 0.008). Receiver operating characteristic (ROC) curve and correlation analysis further confirmed that LncRNA-LUNAR1 expression was closely related to chronic inflammatory diseases, especially diabetes (area = 0.644, p = 0.001; 95% CI, 0.562-0.726). Furthermore, both CD14⁺⁺CD16^- monocytes (r = - 0.37; p < 0.001) and CCL2 levels (r = - 0.35; p < 0.001) negatively affected the expression of LncRNA-LUNAR1. LncRNA-LUNAR1 expression was positively correlated with coronary collaterals in patients with CTO. Inflammatory factors, including CD14⁺⁺CD16^- monocytes and CCL2, may be risk factors affecting LncRNA-LUNAR1 expression.

Recanalization of an atretic intramural left main coronary artery after bypass surgery in a pediatric patient with anomalous aortic origin of the left main coronary artery arising from the right sinus of Valsalva

We report a pediatric patient with nonatherosclerotic chronic total occlusion (CTO) of the left main coronary artery (LMCA) leading to complete LMCA atresia which was successfully recanalized via retrograde techniques through a previous internal mammary bypass graft. After the CTO was treated, the artery was found to be anomalous off the right cusp with an intramural coarse and slit-like orifice. The patient's ischemic symptoms resolved after Percutaneous Coronary Intervention (PCI), and she has continued to do well.

Relationship of myocardial hibernation, scar, and angiographic collateral flow in ischemic cardiomyopathy with coronary chronic total occlusion

BACKGROUND

The relationship between myocardial viability and angiographic collateral flow is not fully elucidated in ischemic cardiomyopathy (ICM) with coronary artery chronic total occlusion (CTO). We aimed to clarify the relationship between myocardial hibernation, myocardial scar, and angiographic collateral flow in these patients.

METHODS AND RESULTS

Seventy-one consecutive ICM patients with 122 CTOs and 652 dysfunctional segments within CTO territories were retrospectively analyzed. Myocardial hibernation (perfusion-metabolism mismatch) and the extent of 18F-fluorodeoxyglucose (FDG) abnormalities were assessed using 99mTc-sestamibi and 18F-FDG imaging. Myocardial scar was evaluated by late gadolinium enhancement (LGE) cardiac magnetic resonance (CMR) imaging. Collateral flow observed on coronary angiography was assessed using Rentrop classification. In these patients, neither the extent nor frequency of myocardial hibernation or scar was related to the status of collateral flow. Moreover, the matching rate in determining myocardial viability was poor between any 2 imaging indices. The extent of 18F-FDG abnormalities was linearly related to the extent of LGE rather than myocardial hibernation. Of note, nearly one-third (30.4%) of segments with transmural scar still had hibernating tissue. Hibernation and non-transmural scar had higher sensitivity (63.0% and 66.7%) than collateral flow (37.0%) in predicting global functional improvement.

CONCLUSIONS

Angiographic collateral cannot accurately predict myocardial viability, and has lower sensitivity in prediction of functional improvement in CTO territories in ICM patients. Hence, assessment of myocardial viability with non-invasive imaging modalities is of importance. Moreover, due to the lack of correlation between myocardial hibernation and scar, these two indices are complementary but not interchangeable.

Exercise Training as a Mediator for Enhancing Coronary Collateral Circulation: A Review of the Evidence

Coronary collateral vessels supply blood to areas of myocardium at risk after arterial occlusion. Flow through these channels is driven by a pressure gradient between the donor and the occluded artery. Concomitant with increased collateral flow is an increase in shear force, a potent stimulus for collateral development (arteriogenesis). Arteriogenesis is self-limiting, often ceasing prematurely when the pressure gradient is reduced by the expanding lumen of the collateral vessel. After the collateral has reached its self-limited maximal conductance, the only way to drive further increases is to re-establish the pressure gradient.

During exercise, the myocardial oxygen demand is increased, subsequently increasing coronary flow. Therefore, exercise may represent a means of driving augmented arteriogenesis in patients with stable coronary artery disease. Studies investigating the ability of exercise to drive collateral development in humans are inconsistent. However, these inconsistencies may be due to the heterogeneity of assessment methods used to quantify change. This article summarises current evidence pertaining to the role of exercise in the development of coronary collaterals, highlighting areas of future research.

Lipoprotein (a) interactions with cholesterol-containing lipids on angiographic coronary collateralization in type 2 diabetic patients with chronic total occlusion

Background

We investigated whether or to what extent the interaction of lipoprotein (a) [Lp(a)] with cholesterol-containing lipids was associated with angiographic coronary collateralization in type 2 diabetic patients with chronic total occlusion.

Methods

Serum levels of Lp(a), total cholesterol, low-density lipoprotein–cholesterol (LDL-C), high-density lipoprotein–cholesterol (HDL-C), and triglyceride were determined and non-HDL-C was calculated in 706 type 2 diabetic and 578 non-diabetic patients with stable coronary artery disease and angiographic total occlusion of at least one major coronary artery. The degree of collaterals supplying the distal aspect of a total occlusion from the contra-lateral vessel was graded as poor (Rentrop score of 0 or 1) or good coronary collateralization (Rentrop score of 2 or 3).

Results

For diabetic and non-diabetic patients, Lp(a), total cholesterol, LDL-C, and non-HDL-C levels were higher in patients with poor coronary collateralization than in those with good collateralization, whereas HDL-C and triglyceride levels were similar. After adjustment for potential confounding factors, tertiles of Lp(a), total cholesterol, LDL-C and non-HDL-C remained independent determinants for poor collateralization. A significant interaction between Lp(a) and total cholesterol, LDL-C or non-HDL-C was observed in diabetic patients (all P interaction < 0.001) but not in non-diabetics. At high tertile of total cholesterol (≥ 5.35 mmol/L), LDL-C (≥ 3.36 mmol/L) and non-HDL-C (≥ 4.38 mmol/L), diabetic patients with high tertile of Lp(a) (≥ 30.23 mg/dL) had an increased risk of poor collateralization compared with those with low tertile of Lp(a) (< 12.66 mg/dL) (adjusted OR = 4.300, 3.970 and 4.386, respectively, all P < 0.001).

Conclusions

Increased Lp(a) confers greater risk for poor coronary collateralization when total cholesterol, LDL-C or non-HDL-C are elevated especially for patients with type 2 diabetes.

Electronic supplementary material

The online version of this article (10.1186/s12933-019-0888-z) contains supplementary material, which is available to authorized users.

Differences in patients and lesion and procedure characteristics depending on the age of the coronary chronic total occlusion

Introduction

Whether duration of chronic total occlusion (CTO) affects lesion and procedural characteristics remains largely unknown.

Aim

To investigate whether CTO duration influences lesion characteristics and revascularization success.

Material and methods

EuroCTO Registry data on patients who had CTO percutaneous coronary intervention between January 2015 and April 2017 were analyzed. Three groups were created based on occlusion age: 3 to 6 months (n = 1415), 7 to 12 months (n = 973), > 12 months (n = 1656).

Results

Patients with greater CTO duration were older (63.0 (56.0–70.0); 63.0 (56.0–71.0); 66.0 (59.0–73.0) years respectively; p < 0.001), had more 3-vessel disease (32.2%; 30.9%; 46.1% respectively; p < 0.001) and more frequent prior coronary artery bypass grafting (8.2%; 9.9%; 29.4% respectively; p < 0.001). In multivariate analysis, occlusion duration was associated with moderate/severe calcification (OR = 1.52; 95% CI: 1.28–1.80; p < 0.001), lesion length > 20 mm (OR 1.77; 95% CI 1.49–2.10; p < 0.001), and collateral circulation Werner type 2 (OR = 1.20; 95% CI: 1.01–1.43; p = 0.041). The CTO duration was associated with lower procedural success (OR for success 0.60; 95% CI: 0.46–0.79; p < 0.001). In multivariate analysis in-hospital adverse events did not differ according to duration of CTO.

Conclusions

Coronary artery CTO duration is associated with greater extent of calcification, lesion length, development of collateral circulation and, most importantly, with lower procedural success.

Impact of chronic total occlusion lesion length on six-month angiographic and 2-year clinical outcomes

Background

Successful management of chronic total occlusion (CTO)by percutaneous coronary intervention (PCI) is known to be associated with better clinical outcomes than failed PCI. However, whether angiographic and clinical outcomes following PCI for long CTO lesions differ from those following PCI for short CTO lesions in the drug eluting stent (DES) era remains unknown. We therefore investigated whether CTO lesion length can significantly influence6-month angiographic and 2-year clinical outcomes following successful CTO PCI.

Methods and results

A total of 235 consecutive patients who underwent successful CTO intervention were allocated into either the long or short CTO group according to CTO lesion length. Six-month angiographic and 2-year clinical outcomes were then compared between the 2groups. We found that baseline clinical characteristics were generally similar between the 2 groups. Exceptions were prior PCI, which was more frequent in the long CTO group, and bifurcation lesions, which were more frequent in the short CTO group. Apart from intimal dissection, which was more frequent in the long than short CTO group, in-hospital complications were also similarly frequent between the 2groups. Furthermore, both groups had similar angiographic outcomes at 6 months and clinical outcomes at 2 years. However, the incidence of repeat PCI(predominantly target vessel revascularization),was higher in the long than short CTO group, with our multivariate analysis identifying long CTO as an important predictor of repeat PCI (odds ratio, 4.26;95% confidence interval, 1.53–11.9; p = 0.006).

Conclusion

The safety profile, 6-month angiographic, and 2-year clinical outcomes of CTO PCI were similar between patients with long and short CTO. However, there was a higher incidence of repeat PCI in long CTO patients despite successful PCI with DESs.

Donor artery stenosis interactions with diastolic blood pressure on coronary collateral flow in type 2 diabetic patients with chronic total occlusion

Background

We investigated whether and to what extent stenosis of predominant collateral donor artery (PCDA) affects coronary collateral flow in relation to blood pressure (BP) in type 2 diabetic patients with chronic total occlusion (CTO).

Methods

Collateral flow index (CFI) as derived from intracoronary pressure distal to occluded segment and mean aortic pressure in 220 type 2 diabetic patients and 220 propensity score matched non-diabetic controls undergoing percutaneous coronary intervention for CTO. The severity of PCDA stenosis was graded according to lumen diameter narrowing.

Results

CFI decreased stepwise from mild to severe stenosis of the PCDA and was lower in diabetic patients with moderate or severe PCDA stenosis than in non-diabetic controls (0.36 ± 0.10 vs. 0.45 ± 0.08, P < 0.001; 0.29 ± 0.09 vs. 0.35 ± 0.08, P = 0.008). When the PCDA was mildly stenotic, CFI increased initially along with a reduction in diastolic BP, and decreased when diastolic BP was below 60 mmHg in diabetic patients (0.38 ± 0.16 vs. 0.57 ± 0.09, P < 0.001). In the presence of moderate PCDA stenosis, diabetic patients had significantly lower CFI compared to non-diabetic controls, with a relative reduction of 19.8% at diastolic BP 70–79 mmHg, 28.2% at 60–69 mmHg and 38.2% below 60 mmHg (all P < 0.05). A severe PCDA stenosis resulted in a more pronounced decrease in CFI, with a relative reduction of 37.3% for diabetics compared to non-diabetics when diastolic BP was below 60 mmHg (P = 0.050).

Conclusions

In the setting of CTO, donor artery stenosis confers greater risk for reduced coronary collateral flow when diastolic BP is decreased. Even a moderate stenosis in the PCDA may be associated with lower collateral flow as diastolic BP decreases below 80 mmHg in type 2 diabetic than in non-diabetic patients.

Total Renal Artery Occlusion: Recovery of Function After Revascularization

Current trends in managing atherosclerotic renal artery stenosis favor medical therapy, on account of negative results from prospective trials of revascularization, such as CORAL and ASTRAL. One result of this trend has been encountering occasional patients with progressive disease, sometimes leading to total arterial occlusion. We illustrate a case of accelerated hypertension with complete renal artery occlusion in which the patient recovered function after surgical bypass and we review the clinical approach used and the advanced imaging modalities available to us. A high index of suspicion and careful radiologic imaging play important roles in selecting patients who may have residual function and may benefit from revascularization. This case illustrates an example whereby restoring renal artery perfusion for carefully selected patients can be life changing, with recovery of kidney function and improved blood pressure, pill burden, and overall quality of life.

Reduced coronary collateralization in type 2 diabetic patients with chronic total occlusion

BACKGROUND

The extent of coronary collateral formation is a primary determinant of the severity of myocardial damage and mortality after coronary artery occlusion. Type 2 diabetes mellitus (T2DM) represents an important risk factor for impaired collateral vessel growth. However, the mechanism of reduced coronary collateralization in type 2 diabetic patients remains unclear.

METHODS

With the reference to the recent researches, this review article describes the pathogenic effects of T2DM on collateral development and outlines possible clinical and biochemical markers associated with reduced coronary collateralization in type 2 diabetic patients with chronic total occlusion (CTO).

RESULTS

Diffuse coronary atherosclerosis in T2DM reduces pressure gradient between collateral donor artery and collateral recipient one, limiting collateral vessel growth and function. An interaction between advanced glycation end-products and their receptor activates several intracellular signaling pathways, enhances oxidative stress and aggravates inflammatory process. Diabetic condition decreases pro-angiogenic factors especially vascular endothelial growth factor and other collateral vessel growth related parameters. Numerous clinical and biochemical factors that could possibly attenuate the development of coronary collaterals have been reported. Increased serum levels of glycated albumin, cystatin C, and adipokine C1q tumor necrosis factor related protein 1 were associated with poor coronary collateralization in type 2 diabetic patients with stable coronary artery disease and CTO. Diastolic blood pressure and stenosis severity of the predominant collateral donor artery also play a role in coronary collateral formation.

CONCLUSIONS

T2DM impairs collateral vessel growth through multiple mechanisms involving arteriogenesis and angiogenesis, and coronary collateral formation in patients with T2DM and CTO is influenced by various clinical, biochemical and angiographic factors. This information provides insights into the understanding of coronary pathophysiology and searching for potential new therapeutic targets in T2DM.

Complex Coronary Hemodynamics - Simple Analog Modelling as an Educational Tool

Objective:

Invasive coronary angiography remains the cornerstone for evaluation of coronary stenoses despite there being a poor correlation between luminal loss assessment by coronary luminography and myocardial ischemia. This is especially true for coronary lesions deemed moderate by visual assessment. Coronary pressure-derived fractional flow reserve (FFR) has emerged as the gold standard for the evaluation of hemodynamic significance of coronary artery stenosis, which is cost effective and leads to improved patient outcomes. There are, however, several limitations to the use of FFR including the evaluation of serial stenoses.

Method:

In this article, we discuss the electronic-hydraulic analogy and the utility of simple electrical modelling to mimic the coronary circulation and coronary stenoses. We exemplify the effect of tandem coronary lesions on the FFR by modelling of a patient with sequential disease segments and complex anatomy.

Results:

We believe that such computational modelling can serve as a powerful educational tool to help clinicians better understand the complexity of coronary hemodynamics and improve patient care.

Predicting ischemic mitral regurgitation in patients with acute ST-elevation myocardial infarction: Does time to reperfusion really matter and what is the role of collateral circulation?

BACKGROUND/OBJECTIVES

Ischemic mitral regurgitation (MR) is an adverse prognostic factor. We aimed to assess the role of time delay from symptom onset to reperfusion, and the impact of collateral circulation to incidence of MR in relation to established echocardiographic and clinical risk factors.

METHODS

Patients with STEMI presenting within 12 h from symptom onset and treated with primary percutaneous coronary intervention (PPCI) at Hospital of Lithuanian University of Health Sciences were enrolled. Echocardiography was performed after PPCI. Based on MR grade, patients were divided into no significant MR (NMR, grade 0-I MR, N = 102) and ischemic MR (IMR, grade ≥ 2 MR, N = 71) groups. Well-developed collaterals were defined as grade ≥ 2 by Rentrop classification. Continuous variables were compared by independent samples Student's T-test. Multivariate logistic regression analysis was used to identify independent predictors of ischemic MR.

RESULTS

Time to reperfusion, MI localization, TIMI flow before/after PCI was similar between the groups. IMR group patients were elder, more often females and non-smokers, had lower body mass index, higher prevalence of multi-vessel coronary artery disease (CAD), better-developed collateral supply, greater left ventricular end-diastolic diameter index, left atrial index, pulmonary artery systolic pressure and lower ejection fraction. Multivariate logistic regression analysis revealed that ischemic MR is predicted by female gender, well-developed collateral supply, presence of multi-vessel CAD, and lower EF.

CONCLUSION

In acute STEMI significant MR is unrelated to ischemic time and is predicted by female gender, lower EF, multi-vessel CAD and well-developed collateral supply to the infarct region.

Correlation between GDF 15 gene polymorphism and the collateral circulation in acute non-ST segment elevated myocardial infarction

OBJECTIVE

To investigate the correlation between growth differentiation factor 15 (GDF 15) + 157 A/T polymorphism and the formation of collateral circulation in acute non-ST segment elevated myocardial infarction in Han population of Shandong province.

METHOD

The medical records of 200 cases of patients undergoing selective coronary angiography were analyzed, and the arterial blood specimens of included patients were collected before coronary angiography. Based on the results of coronary angiography, patients were divided into acute myocardial infarction (AMI) group and normal control group; AMI group was divided into collateral group and non-collateral group by Rentrop's grading method; polymerase chain reaction-restriction fragment length polymorphism (PCR-RFLP) and DNA sequencing methods were used to analyze the GDF 15 + 157 A/T polymorphism in the two groups.

RESULTS

There were statistically significant differences in GDF 15 + 157 A/T AA and AT distribution between AMI group and the control group (P = 0.002); and there was statistically significant difference in allele frequencies between the two groups (P = 0.006); for AMI group, there were statistically significant differences in GDFAA and AT genotype distribution between patients with and without collateral (P = 0.014), and there was statistically significant difference in allele frequencies between the two (P = 0.025).

CONCLUSION

There was correlation between GDF 15 + 157 A/T polymorphism and the formation of collateral circulation in patients with non-ST-segment elevated myocardial infarction.

Physiologic significance of coronary collaterals in chronic total occlusions

Chronic total occlusions (CTOs) are commonly found in patients with coronary artery disease, and a system of collateral connections are found in almost all of these patients. These collateral vessels serve to prevent myocardial necrosis but are not sufficient to prevent myocardial ischemia during exercise. Unfortunately, the presence of well-developed collaterals has been used as argument against CTO revascularization. Many continue to falsely believe that these patients are "protected" by collaterals and, therefore, CTO recanalization is not indicated. Our knowledge of the physiologic significance of coronary collaterals has increased significantly over the past several years. Studies utilizing coronary pressure and flow velocity have answered a number of basic physiologic questions. We therefore sought to review the evidence for coronary collateral flow and their clinical significance in patients with CTOs.