Coronary collaterals and risk for restenosis after percutaneous coronary interventions: a meta-analysis

Vascular Endothelial Growth Factor (VEGF) and Its Role in the Cardiovascular System

Cardiovascular diseases remain the leading cause of death worldwide, with ischemic heart disease (IHD) as the most common. Ischemia-induced angiogenesis is a process in which vascular endothelial growth factor (VEGF) plays a crucial role. To conduct research in the field of VEGF's association in cardiovascular diseases, it is vital to understand its role in the physiological and pathological processes in the heart. VEGF-based therapies have demonstrated a promising role in preclinical studies. However, their potential in human therapies is currently under discussion. Furthermore, VEGF is considered a potential biomarker for collateral circulation assessment and heart failure (HF) mortality. Additionally, as VEGF is involved in angiogenesis, there is a need to elucidate the impact of VEGF-targeted therapies in terms of cardiovascular side effects.

Good coronary collateral circulation is not associated with better prognosis in patients with chronic total occlusion, regardless of treatment strategy

OBJECTIVE

This study aimed to assess the effects of coronary collateral circulation (CCC) on the prognosis of patients with chronic total occlusion (CTO) under different treatment strategies.

METHODS

We analyzed a total of 1124 patients who were diagnosed with CTO and divided them into groups with good CCC (grade 2 to 3, n = 539) or poor CCC (grade 0 to 1, n = 531). The primary outcome was cardiac death during follow-up; the secondary outcome was major adverse cardiovascular events (MACEs). We also performed subgroup analyses in groups with and without CTO revascularization (CTO-R and CTO-NR, respectively), and sensitivity analyses excluding patients who received failed CTO-PCI to further investigate the effect of CCC.

RESULTS

During a median follow-up duration of 23 months, we did not detect any significant differences between the good CCC group and the poor CCC group in terms of cardiac death (4.2% vs 4.1%; adjusted hazard ratio [HR], 1.01; 95% confidence interval [CI], 0.56-1.83; p = 0.970) and MACEs (23.6% vs 23.2%; adjusted HR, 1.07; 95% CI, 0.84-1.37; p = 0.590). Subgroup analyses according to CTO revascularization showed similar results. In addition, we observed no differences in sensitivity analyses when patients who received failed CTO-PCI were excluded.

CONCLUSION

Good CCC was not associated with a lower risk of cardiac death or MACEs among patients with CTO, regardless of whether the patients received CTO revascularization treatment.

Adenosine-Induced Coronary Steal Is Observed in Patients Presenting With ST-Segment-Elevation Myocardial Infarction

Background Adenosine is used to treat no-reflow in the infarct-related artery (IRA) during ST-segment-elevation myocardial infarction intervention. However, the physiological effect of adenosine in the IRA is variable. Coronary steal-a reduction of blood flow to the distal coronary bed-can occur in response to adenosine and this is facilitated by collaterals. We investigated the effects of adenosine on coronary flow reserve (CFR) in patients presenting with ST-segment-elevation myocardial infarction to better understand the physiological mechanism underpinning the variable response to adenosine. Methods and Results Pressure-wire assessment of the IRA after percutaneous coronary intervention was performed in 93 patients presenting with ST-segment-elevation myocardial infarction to calculate index of microvascular resistance, CFR, and collateral flow index by pressure. Modified collateral Rentrop grade to the IRA was recorded, as was microvascular obstruction by cardiac magnetic resonance imaging. Coronary steal (CFR <0.9), no change in flow (CFR=0.9-1.1), and hyperemic flow (CFR >1.1) after adenosine occurred in 19 (20%), 15 (16%), and 59 (63%) patients, respectively. Patients with coronary steal had higher modified Rentrop score to the IRA (1 [0, 1.75] versus 0 [0, 1], P<0.001) and a higher collateral flow index by pressure (0.25±0.10 versus 0.15±0.10, P=0.004) than the hyperemic group. The coronary steal group also had significantly higher index of microvascular resistance (61.68 [28.13, 87.04] versus 23.93 [14.67, 37.00], P=0.006) and had more disease (stenosis >50%) in the donor arteries (52.63% versus 22.03%, P=0.02) than the hyperemic group. Conclusions Adenosine-induced coronary steal may be responsible for a reduction in coronary flow reserve in a proportion of patients presenting with ST-segment-elevation myocardial infarction. Registration URL: https://www.clinicaltrials.gov; Unique identifier: NCT03145194. URL: https://www.isrctn.com; Unique identifier: ISRCTN3176727.

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.

Incidence of major adverse cardiac events in men wishing to continue competitive sport following percutaneous coronary intervention

BACKGROUND

The new North American guidelines for participation in competitive sport in patients with coronary artery disease (CAD) are less restrictive than previous guidelines.

AIM

To evaluate the incidence of major adverse cardiac events (MACE) in men with CAD who practise intensive physical activity after a stenting procedure. MACE included in-stent restenosis (SR), stent thrombosis (ST), new coronary stenosis (NCS), myocardial infarction, heart failure, cardiac arrest or cardiac death.

METHODS

Asymptomatic men with CAD and a coronary stent who practised regular (>4h/week) sport were included in this retrospective multicentre observational study. All patients presented with left ventricular ejection fraction≥50%, no residual stenosis, and no inducible ischaemia or arrhythmias. Three groups were compared: those undertaking moderate leisure-time sport (MLS), intensive leisure-time sport (ILS) or competitive sport (CS). During follow-up, all patients had a yearly routine cardiology evaluation.

RESULTS

A total of 108 men with CAD (57.3±9.1 years) were included: 29 MLS, 58 ILS, and 21 CS. During follow-up (57.6±46.0 months) the incidence of MACE was 15.7% (SR=5, SR+NCS=4, ST=4, NCS=4) and occurred during physical exertion in 59% of patients. ST was more frequent in the CS (n=3) than in the MLS (n=1) or ILS (n=0) groups, especially in patients with bare-metal stents.

CONCLUSIONS

The incidence of MACE was 15.7%, and only ST was significantly more frequent in CS patients than in MLS or ILS patients. Our data support the new US guidelines for exercise eligibility in men with CAD.

Prognostic value of coronary collaterals in patients with acute coronary syndromes

BACKGROUND

The presence of good coronary collateral circulation (CCC) can protect and preserve myocardium from ischemia, increase myocardial contractility, and reduce adverse clinical events. However, its impact on mortality is still a topic of debate, particularly in acute coronary syndrome (ACS). The aim of this study was to investigate the association of CCC with cardiac risk factors and in-hospital mortality in patients hospitalized with a diagnosis of ACS.

METHODS

The study population included 2286 patients with ACS who underwent coronary angiography and were found to have at least 90% significant lesion in at least one major coronary artery. The CCC was graded according to the Rentrop classification. The patients were classified into a poor CCC group (Rentrop grades 0-1, n=1859) or a good CCC group (Rentrop grades 2-3, n=427).

RESULTS

Patients with good CCC had more high-risk patient characteristics such as older age, higher rate of Killip class of at least 2 at admission, lower left ventricular ejection fraction, and impaired renal functions compared with the patients with poor CCC. In multivariate analysis, the presence of good CCC [odds ratio (OR): 2.000; 95% confidence interval: 1.116-3.585; P=0.020], left ventricular ejection fraction less than 40% (OR: 2.381; P=0.003), Killip class of at least 2 at admission (OR: 3.609; P<0.001), age of at least 65 years (OR: 2.975; P=0.003), and hemoglobin (OR: 0.797; P=0.003) were independent predictors of in-hospital mortality.

CONCLUSION

In contrast to previous studies, our study did not confirm a beneficial role of good CCC in patients with ACS; the presence of good CCC was even independently associated with increased in-hospital mortality in the multivariate analysis.

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.

The role of coronary artery collaterals in the preservation of left ventricular function: a study to address a long-standing controversy

Introduction:

The functional significance of coronary artery collateral (CAC) vasculature in humans has been debated for decades and this has been compounded by the lack of a standard, systematic, objective method of grading and documenting CAC flow in man. CACs serve as alternative conduits for blood in obstructive coronary artery disease. This study aimed to evaluate the impact of CACs on left ventricular function in the presence of total coronary arterial occlusion.

Methods:

The study group included the coronary angiographic records of 97 patients (mean age: 59 ± 8 years). CACs were graded from 0–3 based on the collateral connection between the donor and recipient arteries. Left ventricular function was computed from the ventriculogram and expressed as ejection fraction (EF).

Results:

The mean EF of the patients with grades 0, 1, 2 and 3 CACs were calculated as 50.4, 47, 60.5 and 70%, respectively. A significant difference was recorded in the mean EF calculated for the different CAC grades (p = 0.001). There was a significant positive correlation (p < 0.001; r = 0.478) between the mean EF and the CAC grades.

Conclusion:

The patients with better coronary collateral grades had a higher mean EF. Therefore, as the grade of CACs increased, there was an improvement in their ability to preserve left ventricular function.

A Comparison of Fully-Coupled 3D In-Stent Restenosis Simulations to In-vivo Data

We describe our fully-coupled 3D multiscale model of in-stent restenosis, with blood flow simulations coupled to smooth muscle cell proliferation, and report results of numerical simulations performed with this model. This novel model is based on several previously reported 2D models. We study the effects of various parameters on the process of restenosis and compare with in vivo porcine data where we observe good qualitative agreement. We study the effects of stent deployment depth (and related injury score), reendothelization speed, and simulate the effect of stent width. Also we demonstrate that we are now capable to simulate restenosis in real-sized (18 mm long, 2.8 mm wide) vessel geometries.

Long-term prognostic value of QRS score in patients with successfully recanalized coronary chronic total occlusion and construction of a predictive nomogram model

BACKGROUND

Few studies have evaluated the prognostic value of QRS score in patients with coronary chronic total occlusion (CTO) after successful recanalization.

METHODS

A total of 474 patients with successfully recanalized coronary CTO were finally included in our study and were followed up for 34.0±5.3months. They were divided into 3 groups: QRS score≥8, QRS score 4-7 and QRS score 0-3. The primary outcome was composite endpoint of major adverse cardiac and cerebral events (MACCEs). A predictive nomogram was established to predict prognosis for MACCEs, and the predictive accuracy of the nomogram was determined by concordance index.

RESULTS

We found that QRS score correlated moderately with wall motion score index (WMSI) (r=0.551, p<0.001), left ventricular ejection fraction (LVEF) (r=-0.339, p<0.001) and coronary collateral circulation (CCC) (r=-0.569, p<0.001). During follow-up, patients with higher QRS score were observed to undergo poor prognosis. After multivariable adjustment, QRS score was still a significant independent predictor for MACCEs [(hazard ratio 1.28, 95% CI 1.18-1.39, p<0.001) in model 1,(hazard ratio 1.30, 95% CI 1.21-1.41, p<0.001) in mode2] and mortality[(hazard ratio 1.33, 95% CI 1.14-1.57, p<0.001) in model 1, (hazard ratio 1.49 , 95% CI 1.24-1.79, p<0.001) in model 2]. Moreover, the nomogram could more accurately predict 3-year MACCEs (c-index: 0.84).

CONCLUSION

QRS score is a strong independent predictor of long-term prognosis in patients with coronary CTO successfully recancalized. The proposed nomograms can be used for the prediction of MACCE in this population.

Impact of coronary collateral circulation on angiographic in-stent restenosis in patients with stable coronary artery disease and chronic total occlusion

OBJECTIVE

This study aimed to evaluate the relationship between coronary collateralization and in-stent restenosis (ISR) in stable coronary artery disease patients with chronic total occlusion (CTO) after percutaneous coronary intervention (PCI) with drug-eluting stent (DES) implantation.

METHODS

The degree of coronary collaterals supplying the distal aspect of a total occlusion from the contra-lateral vessel was graded according to Rentrop classification in 216 patients with stable angina undergoing successful DES based PCI for CTO. Univariable and multivariable logistic regression analyses were performed to assess the potential factors related to angiographic ISR during follow-up.

RESULTS

Despite similar number of diseased coronary arteries, good collateralization (Rentrop score 2 or 3) was more frequently associated with right coronary artery occlusion (60%), whereas poor collaterals (Rentrop score 0 or 1) occurred more often in left anterior descending artery occlusion (40%). Despite similar number of CTO intervened, stent length was longer in patients with good collateralization (59±27mm vs 47±23mm, p=0.001). At mean 18months, the rate of ISR did not significantly differ between patients with good collateralization and those with poor collateralization (12.7% vs 20.2%, p=0.148). At multivariable analysis, age (OR 1.058, 95%CI 1.015-1.104, p=0.008), history of diabetes mellitus (OR 2.382, 95%CI 1.109-5.116, p=0.026) and reference CTO vessel diameter (OR 0.219, 95% CI 0.051-0.951, p=0.043) were independent risk factors for ISR while Rentrop collateral grade (OR 0.795, 95% CI 0.365-1.732, p=0.414) was not associated with ISR.

CONCLUSIONS

The occurrence of ISR after successful DES based PCI for CTO may be not influenced by coronary collateralization.

Pathophysiology of coronary collaterals

While the existence of structural adaptation of coronary anastomoses is undisputed, the potential of coronary collaterals to be capable of functional adaptation has been questioned. For many years, collateral vessels were thought to be rigid tubes allowing only limited blood flow governed by the pressure gradient across them. This concept was consistent with the notion that although collaterals could provide adequate blood flow to maintain resting levels, they would be unable to increase blood flow sufficiently in situations of increased myocardial oxygen demand.

However, more recent studies have demonstrated the capability of the collateral circulation to deliver sufficient blood flow even during exertion or pharmacologic stress. Moreover, it has been shown that increases in collateral flow could be attributed directly to collateral vasomotion.

This review summarizes the pathophysiology of the coronary collateral circulation, ie the functional adapation of coronary collaterals to acute alterations in the coronary circulation.

Historical aspects and relevance of the human coronary collateral circulation

In 1669, anastomoses between the right and left coronary artery were first documented by Richard Lower of Amsterdam. Using post-mortem imaging, a debate followed on the existence of structural inter-coronary anastomoses, which was not resolved before the first half of the 20 ieth century in case of the presence of coronary artery disease (CAD), and not before the early 1960 ies in case of the normal human coronary circulation by William Fulton. Functional coronary collateral measurements during coronary interventions were first performed only in the 1970 ies, respectively in the early 1980 ies. In humans, the existence of functional coronary collaterals in the absence of CAD has not been documented before 2003. Though the coronary collateral circulation has been recognized as an alternative source of blood supply to ischemic myocardium, its prognostic significance for the CAD population as a whole has been controversial until recently. The debate was due to different populations examined (acute versus chronic CAD, varying severity of CAD), to variable definitions of the term "prognosis", to insufficient statistical power of the investigation with rare occurrence of prognostic endpoints, to short duration of follow-up and to blunt instruments employed for collateral assessment. Individually, it has been acknowledged that a well functioning collateral supply to a myocardial area at risk for necrosis reduces infarct size, preserves ventricular function, prevents ventricular remodelling and aneurysm formation. Collectively, evidence has accumulated only recently that an extensive coronary collateral circulation is a beneficial prognosticator quoad vitam. In a recent meta-analysis on the topic, the risk ratio to die from any cause for high vs low or absent collateralization in patients with subacute myocardial infarction was 0.53 (95% confidence interval 0.15-1.92; p=0.335), and for patients with acute myocardial infarction, it was 0.63 (95% confidence interval 0.29-1.39; p=0.257)¸ the relative risk to die from any cause for well vs poorly developed collaterals in patients with stable CAD was 0.59 (95% confidence interval 0.39-0.89), p=0.012.

The impact of the coronary collateral circulation on outcomes in patients with acute coronary syndromes: results from the ACUITY trial

OBJECTIVE

We sought to assess the prognostic role of collaterals in a large population of patients presenting with an acute coronary syndrome (ACS).

METHODS

The coronary collateral circulation was assessed by an independent angiographic core laboratory using the Rentrop Score in patients enrolled in the randomised Acute Catheterization and Urgent Intervention Triage Strategy trial.

RESULTS

The cohort comprised 5412 patients with moderate to high risk ACS. A total of 858 patients (16.0%) had visible collaterals while 4554 patients (84.0%) had no collaterals. After multivariable adjustment, there were no differences in clinical outcomes at 1 year between the groups, including major adverse cardiac events (MACE) (HR 0.94 (95% CI 0.76 to 1.16), p=0.55), mortality (HR 1.03 (0.65 to 1.62), p=0.91), myocardial infarction (MI) (HR 1.07 (0.83 to 1.38), p=0.60) and unplanned target vessel revascularisation (TVR) (HR 0.95 (0.71 to 1.28), p=0.75). Similarly, in the subgroup of patients undergoing percutaneous coronary intervention (PCI), the adjusted HR for major adverse cardiac events was 1.1 (0.76 to 1.61), p=0.595; 0.81 (0.10 to 6.44), p=0.999 for mortality; and 0.86 (0.54 to 1.35), p=0.564 for MI. The risk of unplanned TVR was increased (HR 2.74 (1.48 to 5.10), p=0.004).

CONCLUSIONS

In contrast to other studies, this large core laboratory-based analysis does not confirm a beneficial role of visible coronary collateral vessels on clinical outcomes in patients with ACS; the presence of collaterals was even associated with increased mortality in the unadjusted analysis. Collaterals were associated with a higher risk of TVR in patients undergoing PCI, a finding that may not have been fully corrected given confounders and clinical differences between the groups.

TRIAL REGISTRATION

ClinicalTrials.gov Identifier: NCT00093158.

The collateral circulation of the heart

The coronary arteries have been regarded as end arteries for decades. However, there are functionally relevant anastomotic vessels, known as collateral arteries, which interconnect epicardial coronary arteries. These vessels provide an alternative source of blood supply to the myocardium in cases of occlusive coronary artery disease. The relevance of these collateral arteries is a matter of ongoing debate, but increasing evidence indicates a relevant protective role in patients with coronary artery disease. The collateral circulation can be assessed by different methods; the gold standard involves intracoronary pressure measurements. While the first clinical trials to therapeutically induce growth of collateral arteries have been unavailing, recent pilot studies using external counterpulsation or growth factors such as granulocyte colony stimulating factor (G-CSF) have shown promising results.