Degree Of Collateral Circulation Research Articles

Early Restoration of Hypoperfusion Confirmed by Perfusion Magnetic Resonance Image after Emergency Superficial Temporal Artery to Middle Cerebral Artery Anastomosis.

Emergency superficial temporal artery to middle cerebral artery (STA-MCA) anastomosis in patients with large vessel occlusion who fails mechanical thrombectomy or does not become an indication due to over the time window can be done as an alternative for blood flow restoration. The authors planned this study to quantitatively measure the degree of improvement in cerebral perfusion flow using perfusion magnetic resonance imaging (MRI) after bypass surgery and to find out what factors are related to the outcome of the bypass surgery. For a total of 107 patients who underwent emergent STA-MCA bypass surgery with large vessel occlusion, the National Institute of Health stroke scale (NIHSS), modified Rankin score (mRS), infarction volume, and hypoperfusion area volume was calculated, the duration between symptom onset and reperfusion time, occlusion site and infarction type were analyzed. After emergency STA-MCA bypass, hypoperfusion area volume at post-operative 7 days was calculated and analyzed compared with pre-operative hypoperfusion area volume. The factors affecting the improvement of mRS were analyzed. The clinical status of patients who underwent emergency bypass was investigated by mRS and NIHSS before and after surgery, and changes in infarct volume, extent, degree of collateral circulation, and hypoperfusion area volume were measured using MRI and digital subtraction angiography (DSA). The preoperative infarction volume was median 10 mL and the hypoperfusion area volume was median 101 mL. NIHSS was a median of 8 points, and the last normal to operation time was a median of 60.7 hours. STA patency was fair in 97.1% of patients at 6 months follow-up DSA and recanalization of the occluded vessel was confirmed at 26.5% of patients. Infarction volume significantly influenced the improvement of mRS (p=0.010) but preoperative hypoperfusion volume was not significantly influenced (p=0.192), and the infarction type showed marginal significance (p=0.0508). Preoperative NIHSS, initial mRS, occlusion vessel type, and last normal to operation time did not influence the improvement of mRS (p=0.272, 0.941, 0.354, and 0.391). In a patient who had an acute cerebral infarction due to large vessel occlusion with large ischemic penumbra but was unable to perform mechanical thrombectomy, STA-MCA bypass could be performed. By using time-to-peak images of perfusion MRI, it is possible to quickly and easily confirm that the brain tissue at risk is preserved and that the ischemic penumbra is recovered to a normal blood flow state.

Automated scoring of collaterals, blood pressure, and clinical outcome after endovascular treatment in patients with acute ischemic stroke and large-vessel occlusion.

IntroductionWe aimed to determine whether the degree of collateral circulation is associated with blood pressure at admission in acute ischemic stroke patients treated with endovascular treatment and to determine its prognostic value.MethodsWe evaluated patients with anterior large vessel occlusion treated with endovascular treatment in a single-center prospective registry. We collected clinical and radiological data. Automated and validated software (Brainomix Ltd., Oxford, UK) was used to generate the collateral score (CS) from the baseline single-phase CT angiography: 0, filling of ≤10% of the occluded MCA territory; 1, 11–50%; 2, 51–90%; 3, >90%. When dichotomized, we considered that CS was good (CS = 2–3), or poor (CS = 0–1). We performed bivariate and multivariable ordinal logistic regression analysis to predict CS categories in our population. The secondary outcome was to determine the influence of automated CS on functional outcome at 3 months. We defined favorable functional outcomes as mRS 0–2 at 3 months.ResultsWe included 101 patients with a mean age of 72.1 ± 13.1 years and 57 (56.4%) of them were women. We classified patients into 4 groups according to the CS: 7 patients (6.9%) as CS = 0, 15 (14.9%) as CS = 1, 43 (42.6%) as CS = 2 and 36 (35.6%) as CS = 3. Admission systolic blood pressure [aOR per 10 mmHg increase 0.79 (95% CI 0.68–0.92)] and higher baseline NIHSS [aOR 0.90 (95% CI, 0.84–0.96)] were associated with a worse CS. The OR of improving 1 point on the 3-month mRS was 1.63 (95% CI, 1.10–2.44) favoring a better CS (p = 0.016).ConclusionIn acute ischemic stroke patients with anterior large vessel occlusion treated with endovascular treatment, admission systolic blood pressure was inversely associated with the automated scoring of CS on baseline CT angiography. Moreover, a good CS was associated with a favorable outcome.

The role of coronary collateral circulation in patients presenting with acute left main coronary artery occlusion

Abstract Introduction Acute occlusion of the unprotected left main coronary artery (LMCA) is an uncommon occurrence associated with a dismal prognosis. Whereas the role of early recruited coronary collateral circulation (CC) in prognosis of ST-segment elevation acute myocardial infarction (STEMI) patients is still controversial, it seems to be important in patients with acute LMCA occlusion. This study aimed to evaluate the coronary CC in patients with acute LMCA occlusion and its impact in short and long-term outcomes. Methods In a retrospective two-center study, we identified 7630 patients with STEMI or high-risk non-ST segment elevation myocardial infarction who underwent emergent coronary angiography between January 2008 and December 2020. Among this cohort, we analyzed 83 patients who presented with unprotected LMCA acute occlusion (Thrombolysis In Myocardial Infarction – TIMI ≤2) and classified them in 2 groups based on the degree of CC through the right coronary artery as seen in the emergent angiography: patients with no filling of collateral vessels or filling of collateral vessels without any epicardial filling of the occluded vessel [Rentrop class 0–1 (71 patients)]; and patients with partial or complete epicardial filling by collateral vessels [CC Rentrop class 2–3 (12 patients)]. Results Compared to patients with CC Rentrop 0–1, patients with CC Rentrop 2–3 presented significantly later to medical attention (symptom to coronary angiography time 8.7 vs 4.3 hours, p=0.02). Despite that, patients with CC Rentrop 2–3 had a significantly lower prevalence of cardiogenic shock at admission (16.7 vs 57.7%, p=0.01). During hospitalization, Killip class III-IV presentation (33.3 vs 88.7%, p<0.001) and inotropic/vasopressor therapy use (25.0 vs 69.0%, p=0.01) were less frequent in CC Rentrop 2–3 patients. The CC Rentrop 2–3 group had a significantly lower in-hospital (16.7 vs 53.5%, p=0.02) and 30-day mortality (9.1 vs 52.2%, p=0.01). In patients surviving hospitalization there was no significant difference in 1-year (30.0 vs 19.4%, p=0.48) and 5-year mortality (70.0 vs 77.4%, p=0.68). Conclusion A well-developed coronary CC was associated to lower short-term mortality in patients presenting with acute occlusion of the unprotected LMCA. Nevertheless, in patients surviving index-event, there was no difference in the long-term outcomes. Further studies are needed to clarify if clinical approach (eg. early short-term mechanical circulatory support) of patients with CC Rentrop 0–1 should be different from those with CC Rentrop 2–3 in order to improve the outcomes of the former patients. Funding Acknowledgement Type of funding sources: None.

Prestroke statin use enhances collateralization in acute ischemic stroke patients

Statin therapy has been shown to be effective in the prevention of ischemic stroke. In addition, recent studies have suggested that prior statin therapy could lower the initial stroke severity and improve stroke functional outcomes in the event of stroke. It was speculated that prestroke statin use may enhance collateral circulation and result in favorable functional outcomes. The aim of the study was to investigate the association of prestroke statin use with leptomeningeal collaterals and to determine the association of prestroke statin use with stroke severity and functional outcome in acute ischemic stroke patients. We prospectively and consecutively enrolled 239 acute ischemic stroke patients with acute infarction due to occlusion of the middle cerebral artery within 24 h in the neurology department of West China Hospital from May 2011 to April 2017. Computed tomographic angiography (CTA) imaging was performed for all patients to detect middle cerebral artery thrombus; regional leptomeningeal collateral score (rLMCS) was used to assess the degree of collateral circulation; the National Institutes of Health Stroke Scale (NIHSS) was used to measure stroke severity at admission; the modified Rankin scale (mRS) was used to measure outcome at 90 days; and premorbid medications were recorded. Univariate and multivariate analyses were performed. Overall, 239 patients met the inclusion criteria. Fifty-four patients used statins, and 185 did not use statins before stroke onset. Prestroke statin use was independently associated with good collateral circulation (rLMCS > 10) (odds ratio [OR], 4.786; 95% confidence interval [CI], 1.195-19.171; P = 0.027). Prestroke statin use was not independently associated with lower stroke severity (NIHSS score≤14) (OR, 1.955; 95% CI, 0.657-5.816; p = 0.228), but prestroke statin use was independently associated with favorable outcome (mRS score≤2) (OR, 3.868; 95% CI, 1.325-11.289; P = 0.013). Our findings suggest that prestroke statin use was associated with good leptomeningeal collaterals and clinical outcomes in acute ischemic stroke (AIS) patients presenting with occlusion of the middle cerebral artery. However, clinical studies should be conducted to verify this claim.

Abstract WMP120: Pre-stroke Statin Enhancement of Collateralization in Acute Ischemic Stroke

Background: Recent studies suggested that prior statin therapy could lower the initial stroke severity and improve stroke functional outcome in case of stroke onset. It was speculated that pre-stroke statin may enhance collateral circulation and result in favorable functional outcome. This study aimed to investigate the association of pre-stroke statin use with leptomeningeal collaterals in acute ischemic stroke patients. Methods: We prospectively and consecutively enrolled 239 acute ischemic stroke patients with acute infarction due to occlusion of the middle cerebral artery within 24 hours from May 2011 to April 2017. CTA imaging was performed for all patients to detect middle cerebral artery thrombus; regional leptomeningeal collateral score (rLMCS) was used to assess the degree of collateral circulation; admission NIHSS was used to measure stroke severity; modified Rankin scale (mRS) at 90 day was used to measure outcome. Univariate and multivariate analyses were performed. Results: 239 patients met inclusion criteria. 54 patients use statin before stroke onset. Pre-stroke statin use was independently associated with good collateral circulations (rLMCS>10) (OR, 4.786; 95% CI, 1.195 - 19.171; P = 0.027). Pre-stroke statin use was not independently associated with lower stroke severity (NIHSS≤14) (OR, 1.955; 95%CI, 0.657- 5.816; P = 0.228), but pre-stroke statin use was independently associated with good outcome (mRS≤2) (OR, 3.868; 95%CI, 1.325 - 11.289; P = 0.013). Conclusion: Pre-stroke statin use seems enhance collateralization and improve clinical outcomes in patients with acute stroke. However, clinical controlled studies should be used to verify this claim.

Maintaining the permanence principle for death during in situ normothermic regional perfusion for donation after circulatory death organ recovery: A United Kingdom and Canadian proposal.

There is international variability in the determination of death. Death in donation after circulatory death (DCD) can be defined by the permanent cessation of brain circulation. Post‐mortem interventions that restore brain perfusion should be prohibited as they invalidate the diagnosis of death. Retrieval teams should develop protocols that ensure the continued absence of brain perfusion during DCD organ recovery. In situ normothermic regional perfusion (NRP) or restarting the heart in the donor's body may interrupt the permanent cessation of brain perfusion because, theoretically, collateral circulations may restore it. We propose refinements to current protocols to monitor and exclude brain reperfusion during in situ NRP. In abdominal NRP, complete occlusion of the descending aorta prevents brain perfusion in most cases. Inserting a cannula in the ascending aorta identifies inadequate occlusion of the descending aorta or any collateral flow and diverts flow away from the brain. In thoracoabdominal NRP opening the aortic arch vessels to atmosphere allows collateral flow to be diverted away from the brain, maintaining the permanence standard for death and respecting the dead donor rule. We propose that these hypotheses are correct when using techniques that simultaneously occlude the descending aorta and open the aortic arch vessels to atmosphere.

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

Introduction and objectivesThe 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. MethodsRetrospective 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. ResultsOf 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). ConclusionsIn this contemporary series, the presence of good CC before PA was not associated with better long-term clinical outcomes.

Impacto de la circulación colateral en el pronóstico a largo plazo de los pacientes tratados con angioplastia primaria

Introduction and objectivesThe 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. MethodsRetrospective 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. ResultsOf 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). ConclusionsIn this contemporary series, the presence of good CC before PA was not associated with better long-term clinical outcomes.Full English text available from: www.revespcardiol.org/en

CT angiography collateral scoring: Correlation with DWI infarct size in proximal middle cerebral artery occlusion stroke within 12 h onset

PurposeIt had been postulated that intra-cranial collateral flow can maintain penumbra and limit infarct growth in acute stroke patients. CT angiography is a frequently performed non-invasive modality for evaluation of intracranial collaterals. In this study, we sought to assess whether there is correlation between degree of collateral circulation as determined by CTA and admission DWI infarct size. Patients and methodsWe analyzed thirty patients with proximal middle cerebral artery occlusion within 12h of onset. The grade of CTA intra-cranial collaterals was evaluated using Maas system and modified Tan scale. Admission DWI infarct volumes were calculated. Spearman correlation coefficient was used to assess relationship between CTA collateral score (CS) and DWI infarct size. ResultsDirect inverse correlation was found between CTA CS and infarct volume (r=−0.5, p=0.001). ROC analysis showed CS as a good discriminator of DWI volume (AUC=0.8, p=0.001). Small infarct size was a significant predictor of good CS (p=0.01). ConclusionsIn patients with major acute MCA occlusion strokes, CTA collateral grading is significantly correlated with admission DWI size. This finding may be relevant for clinical practice and helpful for guiding treatment decision and predicting clinical outcome.

Compensatory intracranial arterial dilatation in extracranial carotid atherosclerosis: the Northern Manhattan study.

There is a scarcity of data supporting the association between atherosclerosis and dolichoectasia in unbiased samples. To test the hypothesis that the association between dolichoectasia and extracranial carotid atherosclerosis depends on the degree of collateral circulation. The Northern Manhattan Study magnetic resonance imaging substudy consists of 1290 participants who remained stroke-free at the time of magnetic resonance imaging. Arterial diameters were collected in all participants with available magnetic resonance angiography. Dolichoectasia was defined as a head-size adjusted diameter >2 standard deviation for each artery. Carotid Doppler was used to evaluate for carotid atherosclerosis (carotid plaque, maximum plaque thickness and carotid intima media thickness). We included 994 participants with available Doppler and magnetic resonance angiography data (mean age 63 years, 60% female). Any dolichoectasia was reported in 16% of participants, 54% had at least one carotid plaque and the mean carotid intima media thickness was 0·92 ± 0·09 mm. After adjusting for demographic and clinical characteristics, there was no association between markers of carotid atherosclerosis and dolichoectasia. However, stratifying by collaterals, it was observed that dolichoectasia was more likely in the anterior and posterior circulations when collaterals were available among participants with carotid atherosclerosis. These associations were confirmed by noting an increment in arterial diameters in the corresponding arteries ipsilateral and contralateral to each carotid as well as in the posterior circulation. We did not find an association of extracranial carotid atherosclerosis with dolichoectasia. However, we found that dolichoectasia is more frequent when intracranial collaterals are available suggesting a compensatory process that needs further investigation.

Abstract W P36: Timing Of Collateral Circulation In Acute Stroke And Its Effect On Predicting Outcomes

Background: We previously reported that Miteff scoring system on pre-tPA CTA was able to predict good functional outcomes in AIS, conversely substantial collateral recruitment on the 24hr CTA led to worse outcomes. We now aimed to determine if the degree of collateral circulation at a specific timing affects its ability to prognosticate outcomes. Methods: Patients treated with IV-tPA during 2018-2012 were included. Patients were stratified by onset-to-CTA timing from 0-60, 61-120, 121-180 and >180 minutes. Two independent neuroradiologists evaluated intracranial collaterals using the Miteff’s system, Maas system, and Alberta Stroke Program Early CT score (ASPECTS) 20-point methodology. Good and severely poor outcomes at 3-months were defined by modified Rankin Scale (mRS) score of 0-1 points and 5-6 points, respectively. SICH was intracranial bleed with NIHSS increase of ≥4 points. Results: 250 Consecutive AAIS patients were included. 52 patients in the 0-60 group, 89 in the 61-120 group, 59 in the 121-180 group and 40 patients in the >180 group. On multivariate analysis from 0-120 minutes, good collaterals by Miteff classification showed a trend to good outcomes (OR 2.460 95%CI 0.985- 9.770, p =0.06) and significantly prevented severely poor outcomes (OR 0.199 95% CI 0.053-0.743, p=0.016) and SICH (OR 0.196 95%CI 0.045-0.862, p=0.03). However the association with prevention of unfavourable outcomes was no longer present in the 121 -180 and > 180 minutes groups. Conclusions: Good collaterals are associated with better functional outcomes however this benefit may be time dependent.

OP-034 The Relationship Between the Degree of Collateral Circulation and Atrial Electromechanical Delay and P Wave Dispersion in Patients with Coronary Collateral Circulation

Coronary collateral circulation (CCC) consists of vascular channels which are activated to maintain perfusion in major epicardial coronary arteries in the development of severe stenosis. The presence of well developed CCC may prevent myocardium from ischemic damage and may improve the prognosis of coronary artery disease. It is known that myocardial ischemia may cause cardiac electrical instability. In this study, it was aimed to assess P wave dispertion (PWD), minimum and maximum P wave duration, intra-atrial and inter-atrial electromechanic delay (AEMD); which are predictors of atrial fibrilation in patients with CCC and evaluate the relation between these parameters and Rentrop classification which shows the degree of collateral development.

Invited Commentary

Invited Commentary

Abstract WP40: “Good” Angiographic Collateral Circulation Correlates With Lower Dwi Infarct Volumes In Acute Ischemic Stroke

Background and purpose Large artery occlusion leads to ischemic stroke which volume is influenced by time from symptom onset. This effect is modulated by several factors, including the presence and degree of collateral circulation. We analyze the correlation between a standard angiographic collateral grading system and DWI infarct volumes. Methods We reviewed a prospectively collected retrospective database of ischemic stroke patients admitted between august of 2006 and december of 2011. We included patients with anterior circulation acute ischemic stroke presenting within 8 hours from symptom onset with large vessel occlusion, who underwent pre-treatment MRI and endovascular therapy. DWI infarct volumes were measured by region of interest. ASITN collateral grading system was used and grouped into “good collaterals” for grades 3 and 4, and “poor collaterals” for grades 0, 1 and 2. JMP statistical software was utilized. Results 152 patients (71 (46.7%) male, mean age: 68±15 years;) were included in the initial analysis. We identified 49 patients who had angiographic collateral circulation grading. Seven patients had ASITN collateral grade 0 with mean infarct volume of 27.6 cc, 25 had collateral grade of 1 with mean infarct volume of 27.9 cc, 10 had collateral grade of 2 with mean infarct volume of 23.4 cc, 5 had collateral grade of 3 with mean infarct volume of 6.3 cc, and 2 had collateral grade of 4 with mean infarct volume of 14.6 cc. Forty two patients had “poor collaterals” with a mean infarct volume of 26.8 cc. Seven patients had “good collaterals” with mean infarct volume of 8.7 cc. When comparing the infarct volumes between these two groups, the difference was statistically significant (p=0.017). Conclusions In anterior circulation acute ischemic stroke, “good” angiographic collateral circulation defined as ASITN grading system of 3 or 4, correlates with lower infarct volumes on presentation.

Albumin Therapy Enhances Collateral Perfusion after Laser-Induced Middle Cerebral Artery Branch Occlusion: A Laser Speckle Contrast Flow Study

Laser speckle contrast (LSC) was used to compare the extent of cortical ischemia in two inbred mouse strains that differed in their degree of collateral circulation, after laser occlusion of the distal middle cerebral artery, and after treatment with 25% albumin (ALB) or saline (control). Sequential LSC images acquired over ∼90 minutes were coaligned, converted to relative flow, and normalized to baseline. After 3-day survival, infarction was quantified by triphenyl tetrazolium chloride or magnetic resonance imaging. In the sparsely collateralized BALB/c strain, mean flow fell to 13% to 14% and 33% to 34% of baseline in central (core) and peripheral (penumbral) regions of interest, and ALB treatment at 30 minutes enhanced perfusion in both regions by ∼2-fold relative to saline, restoring flow to the benign-oligemic range centrally, and to the hyperemic range peripherally. The ALB-induced increment in parenchymal perfusion was disproportionate to the subtle flow increase in the occluded artery itself, suggesting that ALB improved collateral circulation. Cortical infarction in BALB/c mice was reduced 45% by ALB treatment. In contrast to BALB/c mice, the better-collateralized CD-1 strain developed milder ischemia, had smaller infarcts, and showed no differential benefit of ALB. We conclude that where native collateralization is insufficient (BALB/c strain), ALB treatment exerts a significant therapeutic effect after ischemia by augmenting collateral perfusion.

Abstract 2716: Patients with Leukoaraiosis Have Poor Recruitment of Collaterals After Middle Cerebral Artery Occlusion

Background: Previous studies have shown reduced penumbral salvage in ischemic stroke patients with higher leukoaraisosis (LA) volume. Although unproven, decreased cerebral vessel density and diminished capacity of cerebral vessels to dilate in response to reduced blood flow in severe LA, are considered among the factors that might explain the association between LA burden and infarct growth in ischemic stroke. Both of these factors, in theory, might negatively affect the extent of collateral blood flow, an important predictor of tissue and clinical outcome in patients with acute ischemic stroke. In this study, we therefore analyzed whether extent of LA adversely affected the degree of collateral circulation in a cohort of patients presenting with middle cerebral artery occlusion. Methods: We retrospectively analyzed a consecutive series of patients admitted with a diagnosis of middle cerebral artery occlusion. Computed tomography angiography source images (CTA-SI) were used to assess the degree of collateral circulation, based on a previously validated scoring system which grades collateral vessels in the sylvian fissure and leptomeningeal convexity separately on a scale from 1 to 5, with 1 being the worst and 5 the best. The extent of LA was determined on FLAIR images by using the Fazekas scale. Multivariate analysis was used to explore the relationship between extent of LA and degree of collateral circulation, adjusted for other covariates like age, gender, vascular risk factors and time from symptom onset to CTA imaging. Results: A total of 51 patients (31 female, 20 male) were included into the study. LA severity was significantly and negatively correlated with the degree of collateral supply (r=-0.31, p=0.03). LA severity (OR 5.9, 95%CI 1.5-24.0) and history of prior stroke (OR 7.8, 95%CI 1.0-59.3) were the only significant variables associated with insufficient collaterals (defined as a combined sylvian and lepotmeningeal collateral score of 5 or less) in the multivariate logistic regression analysis. Conclusion: Patients with higher LA burden have a poor recruitment of collateral vessels after middle cerebral artery occlusion. This association might contribute to reduced penumbral salvage and increased susceptibility to infarct growth observed in patients with severe LA.

Abstract 124: Collaterals Determine Risk of Early Territorial Stroke and Hemorrhage in the SAMMPRIS Trial

Background: The degree of collateral circulation is a powerful risk factor for recurrent stroke in the setting of medical therapy for symptomatic intracranial atherosclerosis. The impact of collaterals on the short-term risk for stroke in patients treated by stenting or intensive medical therapies is not known. We systematically evaluated baseline angiographic features of collateral circulation and antegrade flow across intracranial stenoses in randomized subjects of the multicenter SAMMPRIS trial and correlated these to their 30-day risk of ischemic stroke. Methods: Digital review of baseline angiograms in SAMMPRIS was conducted to score ASITN/SIR collateral grade and TICI antegrade flow, blind to other data. Dichotomized collateral and TICI scores (none/partial versus complete) were analyzed independently and in combinations with trial endpoints of territorial ischemic stroke or stroke in territory (SIT) and intracranial hemorrhage (ICH) within 30 days in the intensive medical and stenting arms of the study. Log-rank tests with follow-up time censored at 30 days were used in the analysis. Results: Collaterals could be assessed on 376/424 baseline angiography studies available for digital imaging review for the 451 randomized subjects in SAMMPRIS (186 medical, 190 stenting). Early territorial stroke (SIT) occurred in 6/186 (3.2%) subjects in the medical arm and 20/190 (10.5%) after stenting. SIT was not associated with TICI in either arm, whereas collaterals exerted a potent protective influence in medical (p=0.067) and stented (p=0.004) cases, with 0/66 (0%) SIT in the medical arm and 0/51 (0%) SIT in the stented arm when collaterals were complete. SIT in medical cases was associated with partial TICI/partial collaterals (5/25 (20.0%)) versus complete TICI/partial collaterals (1/95 (1.1%)) and partial TICI/complete collaterals (0/66 (0%)), p<0.001. SIT in stented cases was associated with partial TICI/partial collaterals (11/46 (23.9%)) versus complete TICI/partial collaterals (9/93 (9.7%)) and partial TICI/complete collaterals (0/51 (0%)), p<0.001. ICH within 30 days occurred in 0/186 (0%) subjects randomized to medical therapy. In the stenting arm, early ICH occurred in 8/190 (4.2%) and was associated with TICI (p=0.036) and collaterals (p=0.077). Overall, early ICH after stenting was associated with partial TICI/partial collaterals (7/46 (15.2%)) versus complete TICI/partial collaterals (1/93 (1.1%)) and partial TICI/complete collaterals (0/51 (0%)), p<0.001. Conclusions: Patients with impaired collateral flow associated with severe intracranial stenosis had the highest risk for stroke within 30 days, both with intensive medical therapy and as a complication of angioplasty and stenting.

Abstract 76: Collateral Circulation in Endovascular Therapy for Acute Ischemic Stroke: Smaller Strokes, Improved Reperfusion, Less Hemorrhagic Transformation and Better Outcomes

Background: Collateral circulation moderates the impact of acute cerebral occlusion and may influence outcome from recanalization treatment. Noninvasive angiography provides some information on collateral status, but catheter angiography prior to endovascular therapy remains a unique opportunity to verify collateral grade. We conducted a comprehensive study of collaterals in acute anterior circulation occlusion to substantiate previous associations with collaterals and their impact on endovascular stroke therapy. Methods: Consecutive patients undergoing endovascular therapy for acute ischemic stroke due to anterior circulation occlusion were analyzed with respect to collaterals. Collateral grade was assessed with the ASITN/SIR scale on baseline angiography. Univariate and multivariate regression analyses detailed the relationship of collateral grade with clinical, laboratory and imaging parameters. Results: Among 113 patients, mean age was 66.9±17 years, 61.9% were female, and pretreatment NIHSS was median 17 (range 2-38). The proportion of patients in each collateral grade was: 0 - 3.5% 1 - 13.3 %; 2 - 38.9%; 3 - 31%; 4 - 13.3%. Age and gender were not associated with the degree of collateral circulation. Among medical history and laboratory variables, on multivariate ordinal regression, the sole predictor of more robust collaterals was current statin use (b 1.413, p=0.020) and predictors of worse collaterals were history of hyperlipidemia (b -1.872, p=0.001), White population (b -1.361, p=0.007) and higher WBC (b -0.306, p=0.044). More extensive collaterals correlated with smaller baseline DWI lesion volume (b 0.025, p=0.001). Interestingly, angiographic collateral grade did not correlate with PWI lesion volumes for Tmax thresholds at 2, 4, 6, or 8 seconds. More robust collaterals were associated with higher TICI reperfusion rates (ρ 0.191, p=0.043), and lower hemorrhagic transformation rates (ρ -0.229, p=0.015). mRS at discharge inversely correlated with collateral grade (ρ -0.317, p=0.001). Conclusions: The extent of collateral circulation prior to endovascular therapy exhibits a striking impact on achievement of reperfusion, tissue fate and functional outcome. Further research is needed to delineate mechanisms linking statins with better collaterals and biomarkers, such as elevated WBC, for arteriogenesis when collaterals are insufficient.

Biomarkers of Cardiovascular Damage and Dysfunction—An Overview

Acute coronary syndromes (ACS) are due to the rupture or erosion of atheromatous plaques. This produces, depending on plaque size, vascular anatomy and degree of collateral circulation, progressive tissue ischaemia which may progress to cardiomyocyte necrosis and subsequent cardiac remodelling. Cardiac biomarkers can be used for diagnosis and assessment of all of these stages. Markers to detect myocardial ischaemia at the pre-infarction stage are potentially the most interesting but also the most challenging. An ischaemia marker offers the opportunity to intervene to prevent progression to infarction. The challenges with potential ischaemia markers are specificity and the diagnostic reference standard for assessment. To date, only one, ischaemia modified albumin, has reached the point where clinical studies can be performed. The measurement of the cardiac troponins, cardiac troponin T and cardiac troponin I, has become the diagnostic standard as the biomarker of myocardial necrosis. The sensitive nature of troponin measurement has also revealed that myocardial necrosis is also found in a range of other clinical situations. This illustrates the need to use all clinical information for diagnosis of acute myocardial infarction. The measurement of B type natriuretic peptides can be shown to be diagnostic and prognostic for both acute ACS and detecting the sequelae of post infarction myocardial insufficiency. The role of the B type natriuretic peptides in detection of cardiac failure, acute and chronic, is well defined. Their role in ACS remains the subject of further studies.

Novel Index of Coronary Collateral Development as a Useful Predictor of Clinical Outcome in Type 2 Diabetic Patients With Coronary Artery Disease

There is a paucity of information regarding the impact of the coronary collaterals on prognosis in type 2 diabetic (T2DM) patients. We developed a novel index, which considers not only the degree of collateral circulation but also the stimulus of collateral development, and investigated its prognostic value in T2DM patients with coronary artery disease (CAD). One hundred and ninety four consecutive T2DM patients were analyzed and followed for an average of 30 months. We measured the diameter stenosis (DS; %), corrected TIMI frame count (CTFC) and Rentrop score at 3 major epicardial coronary arteries. The collateral development (CD) score was calculated by: (Sigma Rentrop score +1)/Sigma [DS (%) x CTFC] x1,000. During the follow-up, acute cardiovascular events occurred in 49 patients. By multivariate analysis, the CD score was an independent predictor of adverse events not only in the total population (p<0.001), but in all 3 subgroups (p=0.020 for coronary artery bypass grafting, p=0.030 for percutaneous transluminal coronary angioplasty (PTCA) and p=0.003 for the medical group). Furthermore, patients in the tertile with the highest CD score showed improved survival by Kaplan-Meier analysis in the total population, the PTCA and the medical group. The CD score, a novel index of collateral development, may be a useful predictor of clinical outcome in T2DM patients with CAD.