Effect of coronary collaterals on long-term prognosis in patients undergoing primary angioplasty for acute ST-elevation myocardial infarction

Evolving Role of Coronary Collaterals in STEMI Outcomes: A Comparative Analysis of Pandemic and Post-Pandemic Phases

Acute ST-elevation myocardial infarction (STEMI) is a critical condition where coronary collaterals can mitigate myocardial damage. The Coronavirus Disease 2019 (COVID-19) pandemic introduced unique challenges in STEMI management, potentially affecting outcomes. This study evaluates the efficacy of coronary collaterals during the pandemic compared to the post-pandemic period. A review of 1465 STEMI patients treated at a high-volume tertiary care center from April 2020 to December 2022 was conducted. Collaterals were assessed using the Rentrop classification. In-hospital mortality and 1-year major adverse cardiac events (MACE) were analyzed based on collateral status and timeframes. During the pandemic, there was a higher incidence of robust collaterals (28.2% vs 23.2%, P = .04), but they were less protective, with similar in-hospital mortality (14.4% vs 8.1%, P = .07) and 1-year MACE rates (21.9% vs 30.4%, P = .09) across groups. Post-pandemic, robust collaterals showed significant protective effects with reduced in-hospital mortality (3.6% vs 7.4%, P = .04) and 1-year MACE rates (17.1% vs 24.9%, P = .03). These findings highlight a dynamic role of collaterals in STEMI management, with the pandemic impairing their functionality. This underscores the need for adaptive STEMI care strategies, especially during global health crises.

Do collaterals visualized on coronary angiography impact left ventricle ejection fraction among Asian Indians presenting with acute coronary syndrome?-The Deucalion Study

BACKGROUND

The coronary collaterals have been ascribed as a potential alternative source of myocardial perfusion to the extent that some suggest it as a "natural bypass"! We proposed to evaluate the impact of the extent of collaterals on left ventricle ejection fraction among Asian Indians presenting with acute coronary syndrome.

METHODS

This was a retrospective, all-comers study performed on consecutive 3614 patients presenting with the acute coronary syndrome. Angiograms were evaluated for collaterals graded according to Rentrop's classification among group A (grades 0 and 1) and group B (grades 2 and 3) collaterals.

RESULTS

Patients were matched for traditional cardiovascular risk factors in groups A and B as well as for ST elevation myocardial infarction and non-ST elevation myocardial infarction subgroups in both the groups. Grades 2 and 3 collaterals were significantly (P = 0.04) higher in patients with non-ST elevation myocardial infarction-266/1319 (20.17%), as compared to ST elevation myocardial infarction-group 400/2295 (17.43%). Left ventricle ejection fraction on presentation was better preserved in group A as compared to group B in those with double-vessel disease and triple-vessel disease patients with non-ST elevation myocardial infarction, whereas it was better in single-vessel disease and triple-vessel disease patients with ST elevation myocardial infarction. The inverse correlation (r = -0.111, P = 0.000) existed between left ventricle ejection fraction and grades of collaterals.

CONCLUSION

Patients with the single-vessel disease were more likely to have poor coronary collateral as compared to double-vessel disease/triple-vessel disease. Despite higher grade coronary collateral among Asian Indians presenting with acute coronary syndrome, both non-ST elevation myocardial infarction and ST elevation myocardial infarction patients with triple-vessel disease had significantly lower left ventricle ejection fraction. This paradoxically brings out worse left ventricle ejection fraction on presentation in those with double-vessel disease and triple-vessel disease with ST elevation myocardial infarction and single-vessel disease and triple-vessel disease with ST elevation myocardial infarction despite higher grade of coronary collateral representing as "Asian Indian Paradox" in our cohort.

Co-morbidities and co-medications as confounders of cardioprotection-Does it matter in the clinical setting?

The translation of cardioprotection from robust experimental evidence to beneficial clinical outcome for patients suffering acute myocardial infarction or undergoing cardiovascular surgery has been largely disappointing. The present review attempts to critically analyse the evidence for confounders of cardioprotection in patients with acute myocardial infarction and in patients undergoing cardiovascular surgery. One reason that has been proposed to be responsible for such lack of translation is the confounding of cardioprotection by co-morbidities and co-medications. Whereas there is solid experimental evidence for such confounding of cardioprotection by single co-morbidities and co-medications, the clinical evidence from retrospective analyses of the limited number of clinical data is less robust. The best evidence for interference of co-medications is that for platelet inhibitors to recruit cardioprotection per se and thus limit the potential for further protection from myocardial infarction and for propofol anaesthesia to negate the protection from remote ischaemic conditioning in cardiovascular surgery. LINKED ARTICLES: This article is part of a themed issue on Risk factors, comorbidities, and comedications in cardioprotection. To view the other articles in this section visit http://onlinelibrary.wiley.com/doi/10.1111/bph.v177.23/issuetoc.

Can the degree of coronary collateralization be used in clinical routine as a valid angiographic parameter of viability?

The success rate of percutaneous coronary artery intervention (PCI) of chronic total occlusion (CTO) lesions have increased in the recent years. However, improvement of function is only possible when significant myocardial viability is present. One of the most important factors of maintaining myocardial viability is the opening and development of collaterals. Our hypothesis was that with a higher degree of collaterals more viable myocardium is present. In 38 patients we compared the degree of collaterals, evaluated with a conventional coronary angiogram (CCA) and graded by the Rentrop classification to transmural extent of the scar obtained in a viability study with magnetic resonance (MRI). We found a statistically significant association of the degree of collaterals determined with Rentrop method and transmural extent of the scar as measured by CMR (p = 0.001; Tau = -0.144). Additionally, associations showed an increase in the ratio between viable vs. non-viable myocardium with the degree of collaterals. Our study suggests that it may be beneficial to routinely grade the collaterals at angiography in patients with CTO as an assessment of myocardial viability.

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

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

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

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

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.

Spontaneous coronary collateral recruitment in patients with recurrent ST elevation myocardial infarction (STEMI)

The spontaneous recruitment of acute coronary collaterals in the setting of an ST elevation myocardial infarction (STEMI) is seen frequently in those patients undergoing primary percutaneous coronary intervention (pPCI) and is associated with improved clinical outcomes. However, it is unknown whether in patients who present with a recurrent STEMI, the degree of collateral recruitment remains the same as in the index procedure. We reviewed all patients presenting to our tertiary centre with a STEMI undergoing primary or rescue percutaneous coronary intervention (PCI) from July 2010 until December 2018. We identified patients who presented with a recurrent STEMI following their index procedure. We defined patients with poor collateral recruitment as Rentrop grade 0 or 1, whilst patients with robust collateral recruitment as Rentrop grade 2 or 3. Of the 1795 patients who were identified, there were 27 cases in 25 patients who presented with a repeat STEMI following their index procedure. The median time between cases was 12.8 days (IQR 2.3-589.5 days). Compared to the index case, there was no statistically significant difference in the degree of collateral recruitment in recurrent presentations (Z = - 0.378, p = 0.70). In those patients presenting more than 6 months following the index procedure, the median time between cases was 654.5 days (IQR 479.5-1151.9). There was no difference in the degree of collateral recruitment in recurrent presentations (Z = 0.000, p = 1.0). Cases which had poorer collateral recruitment in recurrent presentations were less likely to be current smokers (0% vs 50%, p < 0.001) and less likely to have diabetes (0% vs 27.3%, p < 0.05) The recruitment of spontaneous coronary collaterals remains constant in recurrent STEMI presentations suggesting an innate biological process rather than merely a manifestation of alteration of haemodynamic blood flow. Further investigations to identify these processes is required.

Lipoprotein(a) as a marker for predicting coronary collateral circulation in patients with acute myocardial infarction

Aim: The aim of the present study was to examine the predictive value of lipoprotein(a) (Lp[a]) levels for coronary collateral circulation (CCC) in patients with acute myocardial infarction (AMI). Method & methods: A total of 409 consecutive patients with AMI were enrolled for this study. Patients were divided into two groups according to rentrop grades assessed by coronary angiography: bad (n = 277) and good CCC group (n = 132). Result: Patients with bad CCC had a higher level of Lp(a) than that with good CCC (median Lp[a] 219.1 vs 122.0 mg/l). The area under the receiver-operating characteristic curves of Lp(a) in predicting bad CCC was 0.647 (95% CI: 0.592–0.702) with the cut-off value of 199.0 mg/l. Conclusion: Our data firstly suggested that Lp(a) might be a useful marker for CCC after AMI.

Early recruitment of coronary collateral circulation: impact in late presentation nonreperfused acute coronary occlusion

BACKGROUND

Debate still remains on whether the presence of early recruited collateral circulation (ERCC) in the setting of an acute coronary occlusion (ACO) has a prognosis benefit. Some previous reports have shown lower mortality and morbidity rates in well-collateralized patients compared with those with poorly recruited collateral circulation (PCC), but others have not. In the primary angioplasty era, the role of collateral circulation in these studies may have been influenced by the effect of early reperfusion. The actual impact of ERCC in ACO can be clarified by studying its effect on nonreperfused patients.

OBJECTIVE

This study aimed to compare the 1-year clinical outcome in nonreperfused late presentation ACO in a major coronary artery with ERCC versus PCC.

PATIENTS AND METHODS

Between 2008 and 2015, we included 164 patients with a nonreperfused late presentation ACO. The patients were divided according to the presence of angiographic ERCC (Rentrop 2-3) or PCC (Rentrop 0-1). ERCC was present in 54% of patients. Patients with ERCC less often presented with cardiogenic shock (P=0.02) and the right coronary artery was the most frequent culprit vessel (P=0.02). The presence of PCC was associated independently with higher 1-year cardiovascular mortality [hazard ratio (HR): 6.92; 95% confidence interval (95%CI): 1.37-34.7; P=0.019], 1-year total mortality (HR: 5.79; 95%CI: 1.95-17.1; P=0.001), and 1-year major adverse cardiac event (HR: 8.05; 95%CI: 1.73-37.4; P<0.01).

CONCLUSION

The presence of angiographically PCC in the setting of late presentation nonreperfused ACO is relatively infrequent (46%) and is associated with worse 1-year major clinical outcomes.

Influence of Cardiovascular Risk Factors, Comorbidities, Medication Use and Procedural Variables on Remote Ischemic Conditioning Efficacy in Patients with ST-Segment Elevation Myocardial Infarction

Remote ischemic conditioning (RIC) confers cardioprotection in patients with ST-segment elevation myocardial infarction (STEMI). Despite intense research, the translation of RIC into clinical practice remains a challenge. This may, at least partly, be due to confounding factors that may modify the efficacy of RIC. The present review focuses on cardiovascular risk factors, comorbidities, medication use and procedural variables which may modify the efficacy of RIC in patients with STEMI. Findings of such efficacy modifiers are based on subgroup and post-hoc analyses and thus hold risk of type I and II errors. Although findings from studies evaluating influencing factors are often ambiguous, some but not all studies suggest that smoking, non-statin use, infarct location, area-at-risk of infarction, pre-procedural Thrombolysis in Myocardial Infarction (TIMI) flow, ischemia duration and coronary collateral blood flow to the infarct-related artery may influence on the cardioprotective efficacy of RIC. Results from the on-going CONDI2/ERIC-PPCI trial will determine any clinical implications of RIC in the treatment of patients with STEMI and predefined subgroup analyses will give further insight into influencing factors on the efficacy of RIC.

Macrophage migration inhibitory factor (MIF) is associated with degree of collateralization in patients with totally occluded coronary arteries

BACKGROUND

Collaterals in patients with coronary artery disease (CAD) limit myocardial infarction and improve survival. Macrophage migration inhibitory factor (MIF) might play a role in collateral development. We aimed this study to evaluate the association of Macrophage migration Inhibitory Factor (MIF) with the extent of collateralization in patients with coronary occlusion.

METHODS AND RESULTS

We consecutively enrolled: a) 40 patients undergoing PCI of a chronic coronary total occlusion (CTO); b) 26 patients with ST-elevation myocardial infarction (STEMI) undergoing primary PCI (pPCI) of the infarct-related artery (IRA); c) 12 control patients undergoing angiography without significant coronary artery disease (CTRL). CTO patients were grouped in high (HCG) or low collateralization group (LCG). STEMI patients were grouped in COLL+ or COLL- group depending on the presence of collaterals to the IRA. Blood sampling was performed from the arterial sheath (SYSTEMIC), and distal to the occlusion (LOCAL). SYSTEMIC and LOCAL levels were significantly different between the 3 groups. A progressive increase in MIF ratio (defined as: % (LOCAL-SYSTEMIC)/SYSTEMIC) was observed (CTRL: -0.5[-23;28] vs. CTO: 4[-19;32] vs. STEMI: 55[37;87], p < 0.01). In CTO, MIF ratio was significantly higher in HCG vs. LCG (68 [45;120] vs. 46 [29;66], p = 0.02). In STEMI, MIF ratio was not different between COLL+ and COLL- patients; however, in COLL+, LOCAL was significantly higher as compared with SYSTEMIC (83 ng/ml [63;100] vs. 67 ng/ml [40;79], p = 0.04).

CONCLUSIONS

Local MIF is significantly associated with the extent of collateralization in both acute and chronic total coronary occlusions.

Effect of Coronary Collaterals on Prognosis in Patients Undergoing Primary Percutaneous Coronary Intervention for Acute ST-Segment Elevation Myocardial Infarction: A Meta-Analysis

The impact of coronary collaterals on the prognosis in patients with acute ST-segment elevation myocardial infarction (STEMI) in the era of coronary revascularization remains controversial. The purpose of this meta-analysis was to investigate the effect of coronary collateral on clinical outcomes, especially mortality (≥6 months), in patients undergoing primary percutaneous coronary intervention (PCI) for STEMI. Eligible observational studies were selected by searching PubMed, EMBASE, and Cochrane Library up to August 9, 2017. Overall, 14 observational studies involving 10 411 patients were included. Coronary collaterals were found to reduce the risk of long-term mortality (≥6 months; risk ratio [RR]: 0.65, 95% confidence interval [CI]: 0.55-0.76) as well as in-hospital plus 30-day mortality (RR: 0.61, 95% CI: 0.47-0.78) in patients undergoing PCI for STEMI. In addition, pooling the risk-adjusted or propensity-matched data showed a significant reduction in long-term mortality (RR: 0.68, 95% CI: 0.49-0.95) and in-hospital plus 30-day mortality (RR: 0.27, 95% CI: 0.13-0.55) in patients with collateral circulation. However, no significant difference was found in the risk of recurrent myocardial infarction and target vessel revascularization between the 2 groups. Therefore, it was found that coronary collaterals have a beneficial effect on long-term survival (≥6 months) as well as in-hospital plus 30-day survival in patients undergoing primary PCI for STEMI.

Long-term Intake of Pasta Containing Barley (1-3)Beta-D-Glucan Increases Neovascularization-mediated Cardioprotection through Endothelial Upregulation of Vascular Endothelial Growth Factor and Parkin

Barley (1-3)β-D-Glucan (BBG) enhances angiogenesis. Since pasta is very effective in providing a BBG-enriched diet, we hypothesized that the intake of pasta containing 3% BBG (P-BBG) induces neovascularization-mediated cardioprotection. Healthy adult male C57BL/6 mice fed P-BBG (n = 15) or wheat pasta (Control, n = 15) for five-weeks showed normal glucose tolerance and cardiac function. With a food intake similar to the Control, P-BBG mice showed a 109% survival rate (P < 0.01 vs. Control) after cardiac ischemia (30 min)/reperfusion (60 min) injury. Left ventricular (LV) anion superoxide production and infarct size in P-BBG mice were reduced by 62 and 35% (P < 0.0001 vs. Control), respectively. The capillary and arteriolar density of P-BBG hearts were respectively increased by 12 and 18% (P < 0.05 vs. Control). Compared to the Control group, the VEGF expression in P-BBG hearts was increased by 87.7% (P < 0.05); while, the p53 and Parkin expression was significantly increased by 125% and cleaved caspase-3 levels were reduced by 33% in P-BBG mice. In vitro, BBG was required to induce VEGF, p53 and Parkin expression in human umbelical vascular endothelial cells. Moreover, the BBG-induced Parkin expression was not affected by pifithrin-α (10 uM/7days), a p53 inhibitor. In conclusion, long-term dietary supplementation with P-BBG confers post-ischemic cardioprotection through endothelial upregulation of VEGF and Parkin.

Plasma Omentin-1 Level as a Predictor of Good Coronary Collateral Circulation

Aims: Coronary collateral circulation (CCC) is crucial during an acute ischemic attack. Evidences showed that omentin-1 exhibited remarkable antiatherogenic effects and ischemia-induced revascularization. The aim of this study was to investigate the relationship between plasma omentin-1 levels and CCC in patients with ≥ 90% angiography-proven coronary occlusion.

Methods: 142 patients with ≥ 90% luminal diameter stenosis in at least one major epicardial coronary artery were recruited. Among them, 79 patients with Rentrop 0–1 grade were classified into the poor CCC group and 63 patients with Rentrop 2–3 grade were included into the good CCC group. The association between plasma omentin-1 levels and CCC status was assessed.

Results: Plasma omentin-1 level was significantly higher in patients with good CCC than those with poor CCC (566.57 ± 26.90 vs. 492.38 ± 19.70 ng/mL, p = 0.024). Besides, omentin-1 was positively correlated with total cholesterol (TC), high-density lipoprotein, and gensini score but inversely with hyperlipidemia and body mass index (all p values < 0.05). Multivariate regression analysis indicated that omentin-1 [odds ratio (OR) = 1.002, 95% confidence interval (CI): 1.000 – 1.004, p = 0.041)], TC, the number of the diseased vessels, a higher frequency of left circumflex artery and right coronary artery, chronic total occlusion, and gensini score remained as the independent predictors of good CCC.

Conclusion: Higher plasma omentin-1 level was associated with better CCC development. Our findings suggest that omentin-1 may be an alternative marker for adequate CCC in patients with ≥ 90% coronary occlusion.

Impact of Coronary Collaterals on Long-term Prognosis in Patients Treated With Primary Angioplasty

INTRODUCTION AND OBJECTIVES

The beneficial effect of coronary collateral circulation (CC) in patients with ST-segment elevation myocardial infarction is controversial. The aim of this study was to evaluate the impact of CC before reperfusion with primary angioplasty (PA) on the long-term prognosis of these patients.

METHODS

Retrospective observational study of a cohort of 947 patients treated with PA and TIMI grade ≤ 1 flow in a single center from 2005 to 2013. Propensity score matching was used to create 2 groups of 175 patients each, matched by the degree of CC (Rentrop 0-1 vs Rentrop 2-3). In the matched cohort, we determined the impact of CC on total mortality, cardiovascular mortality, and a combined adverse cardiovascular event endpoint for a median follow-up of 864 (interquartile range, 396-1271) days.

RESULTS

Of a total of 947 patients included, 735 (78%) had Rentrop 0 to 1 and 212 (22%) had Rentrop 2 to 3. During follow-up, 105 patients died, 71 from cardiovascular causes. In the matched cohort, the total mortality rate was similar between the 2 groups (Rentrop 0-1 [8.8%] vs Rentrop 2-3 [6.3%]; HR = 1.22; 95%CI, 0.50-2.94; P = .654). There were no differences in cardiovascular mortality (Rentrop 0-1 [4.6%] vs Rentrop 2-3 [2.3%]; sHR = 0.49; 95%CI, 0.14-1.62; P = .244) or the composite endpoint including cardiovascular death, reinfarction, target vessel revascularization, and coronary artery bypass surgery (Rentrop 0-1 [18.8%] vs Rentrop 2-3 [13.1%]; sHR = 0.68; 95%CI, 0.40-1.15; P = .157).

CONCLUSIONS

In this contemporary series, the presence of good CC before PA was not associated with better long-term clinical outcomes.

Impact of coronary collaterals on in-hospital and 5-year mortality after ST-elevation myocardial infarction in the contemporary percutaneous coronary intervention era: a prospective observational study

OBJECTIVES

To evaluate the short-term and long-term prognostic impacts of acute phase coronary collaterals to occluded infarct-related arteries (IRA) after ST-elevation myocardial infarction (STEMI) in the percutaneous coronary intervention (PCI) era.

DESIGN

A prospective observational study.

SETTING

Osaka Acute Coronary Insufficiency Study (OACIS) in Japan.

PARTICIPANTS

3340 patients with STEMI from the OACIS database who were admitted to hospitals within 24 hours from the onset and who had a completely occluded IRA.

INTERVENTIONS

Patients were divided into 4 groups according to the Rentrop collateral score (RCS) by angiography on admission (RCS-0, no visible collaterals; RCS-1, collaterals without IRA filling; RCS-2, collaterals with partial IRA filling; and RCS-3, collaterals with complete IRA filling).

PRIMARY OUTCOME MEASURES

In-hospital and 5-year mortality.

RESULTS

Patients with RCS-0/3 were older than patients with RCS-1/2, and the prevalence of previous myocardial infarction was highest in patients with RCS-3. Median peak creatinine phosphokinase levels decreased as RCS increases (p<0.001), suggesting the acute cardioprotective effects of collaterals. Although RCS-1 and RCS-2 collaterals were associated with better in-hospital mortality (adjusted OR 0.48, p=0.046 and 0.38, p=0.010 for RCS-1 and RCS-2, respectively) and 5-year mortality (adjusted HR 0.53, p=0.004 and 0.46, p<0.001 for RCS-1 and RCS-2, respectively) as compared with R-0, presence of RCS-3 collaterals was not associated with improved in-hospital (adjusted OR 1.35, p=0.331) and 5-year mortality (adjusted HR 0.98, p=0.920), possibly because worse clinical profiles in patients with RCS-3 may mask mortality benefit of coronary collaterals.

CONCLUSIONS

Presence of acute phase coronary collaterals such as RCS-1 and RCS-2 were associated with better in-hospital and 5-year mortality after STEMI in the contemporary PCI era.

A protective role of early collateral blood flow in patients with ST-segment elevation myocardial infarction

Conflict persists regarding whether the presence of early collateral blood flow to the infarct-related artery has an effective role in reducing infarct size and improving myocardial salvage in patients with ST-segment elevation myocardial infarction (STEMI). We sought to investigate the impact of the collateral circulation on myocardial salvage and infarct size in STEMI patients.

METHODS

In 306 patients who were diagnosed with STEMI and underwent cardiac magnetic resonance within 1 week after revascularization, initial collateral flow to the infarct-related artery was assessed by coronary angiography. Using cardiac magnetic resonance imaging, myocardial infarct size and salvage were measured.

RESULTS

Among 247 patients with preprocedural Thrombolysis in Myocardial Infarction flow 0/1, 54 (22%) patients had good collaterals (Rentrop grade ≥ 2, Collateral Connection Score ≥ 2). Infarct size and area at risk were significantly smaller in patients with good collaterals than those with poor collaterals (infarct size: 17.1 ± 10.1 %LV vs 21.8 ± 10.5 %LV, P = .003, area at risk: 33.8 ± 16.8 %LV vs 38.8 ± 15.5 %LV, P = .039). There was a significant difference of myocardial salvage index between 2 groups (50.9% ± 15.0% vs 43.8% ± 18.5%, P = .005). Poor collateralization was an independent predictor for large infarct size (odd ratio 2.48 [1.28-4.80], P = .007).

CONCLUSIONS

In patients with STEMI, the presence of well-developed collaterals to occluded coronary artery from the noninfarct vessel and its extent were independently associated with reduced infarct burden and improved myocardial salvage. Our results help explain why MI patients with well-developed collateralization have reduced mortality and morbidity.

Collateral Circulation in Chronic Total Occlusions – an interventional perspective

Human coronary collaterals are inter-coronary communications that are believed to be present from birth. In the presence of chronic total occlusions, recruitment of flow via these collateral anastomoses to the arterial segment distal to occlusion provide an alternative source of blood flow to the myocardial segment at risk. This mitigates the ischemic injury. Clinical outcome of coronary occlusion ie. severity of myocardial infarction/ischemia, impairment of cardiac function and possibly survival depends not only on the acuity of the occlusion, extent of jeopardized myocardium, duration of ischemia but also to the adequacy of collateral circulation. Adequacy of collateral circulation can be assessed by various methods. These coronary collateral channels have been used successfully as a retrograde access route for percutaneous recanalization of chronic total occlusions. Factors that promote angiogenesis and further collateral remodeling ie. arteriogenesis have been identified. Promotion of collateral growth as a therapeutic target in patients with no suitable revascularization option is an exciting proposal.

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.

Fractional flow reserve-guided coronary bypass surgery: should surgeons use it?

PURPOSE OF REVIEW

Physiology-based evaluation in stable ischemic heart disease is transforming percutaneous cardiovascular intervention (PCI). Fractional flow reserve (FFR)-guided PCI is associated with more appropriate and beneficial outcomes at lower costs. The surgical community can no longer ignore this development. We review evidence for the rationale, practicality and appropriateness of FFR-guided coronary artery bypass grafting (CABG), as compared with the current conventional, anatomy-based strategy for surgical revascularization.

RECENT FINDINGS

Physiologic evaluation links the nature (anatomic or functional) of coronary stenoses to the perfused myocardium supplied by the target vessel and challenges the use of anatomy as the sole criterion for revascularization intervention. In CABG, a functional perfusion deficit/ischemia identifies myocardial territories that would physiologically benefit from revascularization by grafting beyond the functional stenosis. Conversely, deliberately not grafting beyond an anatomic stenosis would dramatically change the procedure of CABG. Recent studies of functionally guided revascularization (PCI or CABG) support this approach, while recent trials of PCI vs. CABG demonstrated a late survival advantage with anatomy-based CABG. Finally, new intraoperative imaging technologies are elucidating the physiologic consequences of surgical revascularization in real time, yielding insights into resolving this dilemma.

SUMMARY

Physiologic-based revascularization is challenging our thinking about the historic strategy for CABG. Understanding better the physiologic consequences of revascularization will drive the evolution of CABG in the future.

Collateral vessel opacification with CT in patients with coronary total occlusion and its relationship with downstream myocardial infarction

PURPOSE

To assess the correlation between the filling pattern of distal coronary vessels in patients with chronic total occlusion (CTO) observed at coronary computed tomographic (CT) angiography and the extent of downstream myocardial infarction (MI).

MATERIALS AND METHODS

All patients gave written informed consent, and the institutional review board approved the study protocol. A total of 97 patients (mean age, 68.5 years ± 11.5 [standard deviation]; age range, 38-87 years; 77 men, 20 women) with 106 CTOs were prospectively enrolled. Distal filling of the epicardial segment was semiquantitatively classified by using a four-point scale according to patterns at coronary CT angiography (0 = absence of distal filling; 1 = partial distal filling, with a length less than one-third of the segment; 2 = partial distal filling, with a length between one-third and two-thirds of the segment; 3 = complete or partial distal filling, with a length longer than two-thirds of the segment). A coronary CT angiography score of 3 was considered indicative of well-developed collaterals. Downstream MI transmurality and wall motion abnormality were verified semiquantitatively with cardiac magnetic resonance imaging. Mann-Whitney U test and t test were used for comparison.

RESULTS

Coronary CT angiography revealed three lesions with a score of 0, 21 with a score of 1, 35 with a score of 2, and 47 with a score of 3. The non-MI subgroup was associated with higher collateral grading at CT angiography, whereas the transmural MI subgroup was associated with lower collateral grading (P = .005). When compared with the poorly developed (score 0-2) collaterals group, the well-developed (score 3) collateral group correlated to a lower summed transmurality score (P < .001) and a lower summed regional wall motion abnormality score (P = .029).

CONCLUSION

The presence of well-developed distal collaterals as revealed by coronary CT angiography in patients with CTO lesions correlates with the lower frequency and extent of downstream MI.

Interpretation of acute myocardial infarction with persistent 'hyperacute T waves' by cardiac magnetic resonance

Peaked and tall T waves represent a hyperacute electrocardiogram (ECG) manifestation of coronary artery occlusion which usually evolves into ST-segment elevation. We sought to investigate using cardiac magnetic resonance (CMR) the myocardial tissue changes underlying an atypical ECG pattern of presentation of left anterior descending artery (LAD) occlusion consisting of persistent hyperacute T waves and mild ST-segment depression. This ECG pattern is often associated with the presence of collateral circulation, which may modulate myocyte action potential changes in response to ischemia and prevent the appearance of ST-segment elevation. However, CMR findings resembled those of typical anterior myocardial infarction with nearly transmural necrosis in the large myocardial area supplied by LAD. Accordingly, persistent hyperacute T waves should be regarded as an equivalent to ST-segment elevation and immediate reperfusion therapy should be considered.

Effect of collaterals on deaths and re-infarctions in patients with coronary artery disease: a meta-analysis

BACKGROUND

It is generally believed that there is a beneficial effect of collaterals on death and re-infarction statistics in patients with coronary artery disease (CAD) but studies to date are small and inconsistent.

OBJECTIVE

To meta-analyse the studies published in this field in order to obtain more powerful information.

METHODS

We searched Medline and major journals (2000 to 2011) for studies evaluating the effect of coronary collaterals on mortality. Publication bias, lack of heterogeneity, and lack of robustness were assessed using the standard procedures for such purposes.

RESULTS

A total of 10 studies describing mortality, enrolling 6791 participants, were included in this analysis. In patients with collateralisation a significant relation with reduced mortality was seen compared with those without collateralisation, at an odds ratio of 0.47, p < 0.0001, and a reduction in deaths and re-infarctions at 0.54, p < 0.0001. Some publication bias, some heterogeneity and some lack of robustness were demonstrated. A meta-regression with the odds ratios of the presence of traditional atherosclerotic risk factors as predictors and the odds ratios of mortality and the composite deaths and re-infarctions as outcome showed no relationships.

CONCLUSIONS

In CAD patients from the post-percutaneous coronary intervention era the presence of collaterals reduced mortality by 0.47 (p < 0.0001) and deaths and re-infarctions by 0.54 (p < 0.0001). Furthermore, in the present meta-data, the atherosclerotic risk factors were no more present in patients with collaterals than they were in those without.

Frequency of Myocardial Infarction and Its Relationship to Angiographic Collateral Flow in Territories Supplied by Chronically Occluded Coronary Arteries

Background—

Despite complete interruption of antegrade coronary artery flow in the setting of a chronic total occlusion (CTO), clinical recognition of myocardial infarction is often challenging. Using cardiac MRI, we investigated the frequency and extent of myocardial infarction in patients with CTO, and assessed their relationship with regional systolic function and the extent of angiographic collateral flow.

Methods and Results—

We included 170 consecutive patients (median age, 62 years) with angiographically documented CTO. Regional late gadolinium enhancement and wall motion score index were assessed by cardiac MRI with the use of a 17-segment model. Angiographic collateral flow was assessed by the collateral connection grade and the Rentrop score. Evidence of previous myocardial infarction was found in 25% of patients by ECG Q waves, in 69% by regional wall motion abnormality, and in 86% of patients by late gadolinium enhancement. Increased angiographic collateral flow was associated with a lower frequency of Q waves on ECG, and a lower regional wall motion score index, late gadolinium enhancement volume (%), and degree of late gadolinium enhancement transmurality (all P <0.001), as well.

Conclusions—

The frequency of myocardial infarction in territories subtended by CTO is significantly higher than previously recognized. The degree of myocardial injury downstream epicardial CTO is inversely correlated with the degree of angiographic collaterals.

Plasma chemokine levels are associated with the presence and extent of angiographic coronary collaterals in chronic ischemic heart disease

BACKGROUND

In patients with chronic ischemic heart disease (IHD), the presence and extent of spontaneously visible coronary collaterals are powerful determinants of clinical outcome. There is marked heterogeneity in the recruitment of coronary collaterals amongst patients with similar degrees of coronary artery stenoses, but the biological basis of this heterogeneity is not known. Chemokines are potent mediators of vascular remodeling in diverse biological settings. Their role in coronary collateralization has not been investigated. We sought to determine whether plasma levels of angiogenic and angiostatic chemokines are associated with of the presence and extent of coronary collaterals in patients with chronic IHD.

METHODOLOGY/PRINCIPAL FINDINGS

We measured plasma concentrations of angiogenic and angiostatic chemokine ligands in 156 consecutive subjects undergoing coronary angiography with at least one ≥90% coronary stenosis and determined the presence and extent of spontaneously visible coronary collaterals using the Rentrop scoring system. Eighty-eight subjects (56%) had evidence of coronary collaterals. In a multivariable regression model, the concentration of the angiogenic ligands CXCL5, CXCL8 and CXCL12, hyperlipidemia, and an occluded artery were associated with the presence of collaterals; conversely, the concentration of the angiostatic ligand CXCL11, interferon-γ, hypertension and diabetes were associated with the absence of collaterals (ROC area 0.91). When analyzed according to extent of collateralization, higher Rentrop scores were significantly associated with increased concentration of the angiogenic ligand CXCL1 (p<0.0001), and decreased concentrations of angiostatic ligands CXCL9 (p<0.0001), CXCL10 (p = 0.002), and CXCL11 (p = 0.0002), and interferon-γ (p = 0.0004).

CONCLUSIONS/SIGNIFICANCE

Plasma chemokine concentrations are associated with the presence and extent of spontaneously visible coronary artery collaterals and may be mechanistically involved in their recruitment.