Abstract WMP9: Impact of Collateral Blood Flow on Clinical Presentation, Diffusion and Perfusion Imaging, Infarct Growth and Clinical Outcome in the DEFUSE 2 Trial

Stroke ◽  
2013 ◽  
Vol 44 (suppl_1) ◽  
Author(s):  
Michael P Marks ◽  
Maarten G Lansberg ◽  
Michael Mlynash ◽  
John-Marc Olivot ◽  
Matus Straka ◽  
...  
Keyword(s):  
Perfusion Imaging ◽  
Clinical Presentation ◽  
Stroke Severity ◽  
Collateral Flow ◽  
Collateral Blood Flow ◽  
Point Scale ◽  
Median Volume ◽  
And Diffusion ◽  
Blinded Reader ◽  
Good Flow

Objective: To determine the relationships between angiographic collaterals and diffusion/perfusion imaging, subsequent infarct growth and clinical outcomes in DEFUSE 2 study patients. Methods: Patients undergoing endovascular therapy within 12 hours of stroke onset were prospectively enrolled. Only patients with a TICI score of 0, 1 and ICA/M1 occlusion at baseline were included in this analysis. A blinded reader assigned a collateral score using a previously described 5 point scale, from 0 (no collateral flow) to 4 (complete/rapid collaterals to entire ischemic territory). Analysis was dichotomized to poor flow (0-2) versus good flow (3-4). Collateral score was correlated with baseline NIHSS, DWI volume, PWI volume (Tmax > 6), TICI reperfusion, infarct growth and mRS at day 90. Results: Sixty patients had TICI 0, 1 ICA/M1 occlusions and adequate angiographic images to evaluate collaterals. Baseline NIHSS correlated with collateral score (p=0.002). Median NIHSS for patients with poor collateral flow (0-2) was 18 (IQR, 13-22) versus 14 (10-17) for those with good flow (3-4), p=0.025. Baseline T max > 6 volume correlated with collateral score (p=0.002). Median volume of tissue at risk (T max > 6) in those with poor collateral flow was 115 ml (IQR, 74-136) versus 82 (51-109) with good flow, p=0.012. Collateral score did not correlate with baseline DWI volume. TICI reperfusion (0-3) correlated with collateral score (p=0.027). Patients with poor collateral flow had 29% TICI 2b-3 reperfusion versus 65.5% with good flow, p=0.009. Those with poor reperfusion (TICI 0-2a) showed a trend to more infarct growth with poor collaterals, 92 ml (52-194) [mean (IQR)] versus 36 ml (14-106) with good collaterals, p=0.06. Patients with poor collaterals who reperfused (TICI 2b-3) were still likely to have a mRS 0-2 at 90 days compared to those without reperfusion; OR 12 (95% CI, 1.6-98). Conclusion: Collaterals correlate with baseline clinical stroke severity and the PWI volume. In addition, good collaterals correlate with higher rates of reperfusion (TICI 2b-3). When patients do not reperfuse, good collaterals appear to limit infarct growth.

Abstract 188: Correlation of Angiographic Capillary Index Score (CIS) with Diffusion and Perfusion MR Imaging in the DEFUSE 2 Trial

Stroke ◽  
2014 ◽  
Vol 45 (suppl_1) ◽  
Author(s):  
Michael P Marks ◽  
Firas Al-Ali ◽  
Maarten G Lansberg ◽  
Michael Mlynash ◽  
Stephanie M Kemp ◽  
...  
Keyword(s):  
Endovascular Therapy ◽  
Lesion Volume ◽  
Collateral Flow ◽  
Point Scale ◽  
Median Volume ◽  
Perfusion Mr ◽  
Lesion Growth ◽  
Perfusion Mr Imaging ◽  
The Relationship

Objective: The CIS has been shown to be a predictor of good clinical outcome following endovascular therapy for acute ischemic stroke. We undertook this study to determine the relationship between CIS and baseline diffusion-perfusion imaging as well as angiographic collaterals in DEFUSE 2 study patients. Methods: Patients undergoing endovascular therapy within 12 hours of stroke onset were prospectively enrolled. Only patients with an ICA/M1 occlusion and adequate demonstration of the anterior and posterior circulations at baseline angiography were included in this analysis. Blinded reading of the CIS was made using a 4 point scale from 0 (no capillary blush in ischemic territory) to 3 (blush throughout). Analysis was dichotomized to poor CIS (0-1) versus good (2-3). CIS was correlated with baseline DWI volume, PWI volume (Tmax > 6, Tmax>10), an angiographic collateral score (using a previously described 5 point scale) and subsequent infarct growth. Results: Forty-eight patients had ICA/M1 occlusions and adequate angiographic images to evaluate CIS. Baseline DWI lesion volume correlated with CIS (p=0.001). Median DWI volume for patients with poor CIS (0-1) was 28 (IQR, 11-54) versus 13 (3-27) for those with good CIS (2-3), p=0.011. Baseline T max > 6 volume correlated with CIS (p=0.004). Median volume of tissue at risk (T max > 6 sec) in those with poor CIS was 108 ml (IQR, 74-138) versus 69(43-108) with good CIS, p=0.009. Severe T max delay (> 10 sec) also correlated with CIS (p=0.001). CIS was also found to correlate with angiographic collaterals (p=0.006). On follow-up MRI CIS correlated with subsequent lesion growth (p=0.043). Conclusions: CIS provides a rapid angiographic assessment of capillary blush from collateral flow into the ischemic territory and correlates with angiographic collateral scores. In DEFUSE 2 the CIS score was strongly associated with baseline DWI and PWI lesion volumes and subsequent lesion growth.

scholarly journals Predictive Value of CT Perfusion Imaging on the Basis of Automatic Segmentation Algorithm to Evaluate the Collateral Blood Flow Status on the Outcome of Reperfusion Therapy for Ischemic Stroke

2021 ◽  
Vol 2021 ◽  
pp. 1-8
Author(s):  
Qingsong Gong ◽  
Botao Yu ◽  
Mengjie Wang ◽  
Min Chen ◽  
Haowen Xu ◽  
...  
Keyword(s):  
Blood Flow ◽  
Ischemic Stroke ◽  
Perfusion Imaging ◽  
Ct Perfusion ◽  
Automatic Segmentation ◽  
Reperfusion Therapy ◽  
Segmentation Algorithm ◽  
Collateral Flow ◽  
Collateral Blood Flow ◽  
Ct Perfusion Imaging

Our objective was to study the predictive value of CT perfusion imaging based on automatic segmentation algorithm for evaluating collateral blood flow status in the outcome of reperfusion therapy for ischemic stroke. All data of 30 patients with ischemic stroke reperfusion in our hospital were collected and examined by CT perfusion imaging. Convolutional neural network (CNN) algorithm was used to segment perfusion imaging map and evaluate the results. The patients were grouped by regional leptomeningeal collateral score (rLMCs). Binary logistic regression was used to analyze the independent influencing factors of collateral blood flow on brain CT perfusion. The modified Scandinavian Stroke Scale was used to evaluate the prognosis of patients, and the effects of different collateral flow conditions on prognosis were obtained. The accuracy of CNN segmentation image is 62.61%, the sensitivity is 87.42%, the similarity coefficient is 93.76%, and the segmentation result quality is higher. Blood glucose (95% CI = 0.943, P = 0.028 ) and ischemic stroke history (95% CI = 0.855, P = 0.003 ) were independent factors affecting the collateral blood flow status of stroke patients. CBF (95% CI = 0.818, P = 0.008 ) and CBV (95% CI = 0.796, P = 0.016 ) were independent influencing factors of CT perfusion parameters. After 3 weeks of onset, the prognostic function defect score of the good collateral flow group (11.11%) was lower than that of the poor group (41.67%) ( P < 0.05 ). The automatic segmentation algorithm has more accurate segmentation ability for stroke CT perfusion imaging and plays a good auxiliary role in the diagnosis of clinical stroke reperfusion therapy. The collateral blood flow state based on CT perfusion imaging is helpful to predict the treatment outcome of patients with ischemic stroke and further predict the prognosis of patients.

Abstract T P41: Determination of Collateral Supply Patterns Using MR or CT Perfusion Imaging

Stroke ◽  
2014 ◽  
Vol 45 (suppl_1) ◽  
Author(s):  
Cihat Eldeniz ◽  
Yueh Lee ◽  
Maria Gisele Matheus ◽  
Jeffery Keith Smith ◽  
James Faber ◽  
...  
Keyword(s):  
Perfusion Imaging ◽  
Ct Perfusion ◽  
Mapping Method ◽  
Collateral Flow ◽  
Scoring Method ◽  
Flow Mapping ◽  
Flow Maps ◽  
Ct Perfusion Imaging ◽  
Ischemic Tissue ◽  
Flow Information

Introduction: In this study, we sought to develop a collateral flow mapping method based on MR or CT perfusion imaging and compare this method with the digital subtraction angiography (DSA) method. Methods: Ischemic tissue supplied by collateral flow is likely to have delayed tracer arrival but relatively normal flow. In this study, abnormal Tmax (> 6 sec), MTT (4 sec or greater than unaffected hemisphere) and CBF (<40% of unaffected hemisphere) were labeled with green, red and blue, respectively (Fig. A). Any perfusion patterns can then be represented by a combination of this integrated RGB maps (Integrated Collateral flow Maps, iCMaps). 24 patients were included in this study. DSA images were obtained from all patients, whereas MR and CT perfusion images were acquired from 15 and 9 patients, respectively, within 30 hours after MCA occlusion. iCMaps collateral flow was scored independently as follows. iCMaps without any perfusion abnormality was assigned “1”. iCMaps with white as the dominant perfusion pattern was assigned a “5”; while those with a dominant green and yellow pattern were assigned a “2” or a “3”, depending on the relative green and yellow volume. Finally, iCMaps with a white region surrounded with yellow and green was assigned a “4”. Examples of iCMaps scoring are shown in Fig. B. Using a DSA scoring method in the literature5, a score of 1-5 was given independently based on the degree of retrograde collateralization (5: poor collateralization). Results: Good correlation was found between the MR perfusion iCMaps and DSA (DSA=0.70*MR iCMaps+0.54, R=0.75). Moderate correlation was obtained between the CT perfusion iCMaps and DSA (DSA=0.51*CT iCMaps+1.9, R=0.56). Conclusions: Based on the different characteristics of Tmax, MTT and CBF maps, the proposed MR or CT perfusion based iCMaps method can provide DSA comparable collateral flow information.

Abstract P499: The Effect of Small Vessel Disease Burden on Core/Penumbra Mismatch and Outcomes in Extended Window Thrombectomy

Stroke ◽  
2021 ◽  
Vol 52 (Suppl_1) ◽  
Author(s):  
Destiny Hooper ◽  
Tariq Nisar ◽  
Meryim Poursheykhi ◽  
Andy Lin ◽  
C. David McCane ◽  
...  
Keyword(s):  
White Matter ◽  
Perfusion Imaging ◽  
Functional Outcomes ◽  
Time Window ◽  
Small Vessel Disease ◽  
Small Vessel ◽  
Collateral Flow ◽  
Anterior Circulation ◽  
Vessel Occlusion ◽  
Vessel Disease

Objective: Recent studies have shown the benefit of revascularization in select patients with extended window large vessel occlusion (EWLVO). We sought to assess the effect of cerebral small vessel disease (CSVD) burden on eligibility for intervention with mechanical thrombectomy (MT) and functional outcomes in patients with EWLVO. Methods: We conducted a retrospective single-center study of 135 patients with anterior circulation LVO who presented in the extended time window, 6 to 24 hours from LKW, between August 2018 and March 2020. All patients underwent perfusion imaging at initial presentation and those with target ischemic core to penumbra mismatch profiles, as defined by DAWN/DEFUSE3 criteria, were treated with MT. Included patients were evaluated for CSVD burden using T2-FLAIR MRI. The Fazekas scale (0-3) was used to quantify the amount of white matter T2 hyperintense lesions in both the periventricular (PVWM) and deep white matter (DWM). Patients’ functional outcomes were assessed at 90 days using the mRS. Multivariate ordinal logistic regression models were used and adjusted for age, gender, thrombus location and LKW to perfusion imaging time. Patient information was collected from the Houston Methodist Hospital Outcomes Based Prospective Endpoints in Stroke (HOPES) registry. Results: Of the 135 patients, 111 met imaging inclusion criteria for revascularization with MT for EWLVO. MT was deferred in 44 of these patients due to other clinical exclusions or patient refusal. Patients ineligible for MT were approximately 13 times more likely to have a higher PVWM Fazekas grade (OR =13.53, 95% CI. [2.94 - 62.39], p=0.001) and 17 times more likely to have a higher DWM Fazekas grade (OR =17.54, 95% CI. [4.20 - 73.17], p<0.001), when compared to patients who were eligible for MT. Patients who did not meet criteria for MT were nearly 7 times more likely to have poor functional outcomes at 90 days (OR =6.85, 95% CI. [2.09 - 22.44], p=0.001). Conclusion: Based on our analytical cohort of EWLVO patients, those with severe CSVD burden were more likely to be excluded from MT and had worse functional outcomes. Poor cerebrovascular reserve and diminished collateral flow leading to rapid infarct progression in patients with greater CSVD burden may be a potential explanation.

scholarly journals Imaging perfusion deficits, arterial patency and thrombolysis safety and efficacy in acute ischaemic stroke. Anobservational study of the effect of advanced imaging methods in The Third International Stroke Trial (IST-3), arandomised controlled trial

2014 ◽  
Vol 1 (1) ◽  
pp. 1-91 ◽  
Author(s):  
Joanna M Wardlaw ◽  
Trevor Carpenter ◽  
Eleni Sakka ◽  
Grant Mair ◽  
Geoff Cohen ◽  
...  
Keyword(s):  
Ischaemic Stroke ◽  
Perfusion Imaging ◽  
Intracranial Haemorrhage ◽  
Arterial Occlusion ◽  
Lesion Size ◽  
Arterial Stenosis ◽  
Stroke Severity ◽  
Severe Stroke ◽  
The Third ◽  
Stroke Trial

BackgroundIntravenous thrombolysis with recombinant tissue plasminogen activator (rt-PA) improves outcome after an ischaemic stroke but increases the risk of intracranial haemorrhage. Restricting rt-PA to patients with salvageable tissue, or arterial occlusion, might reduce risk, increase benefit and enable treatment at late time windows.ObjectivesTo determine if computed tomography (CT) or magnetic resonance (MR) perfusion or angiography (CTP/CTA; MRP/MRA) imaging provide important information to guide the use of rt-PA up to 6 hours after a stroke.DesignProspective, multicentre, randomised, open, blinded, end-point trial of rt-PA.SettingForty-eight centres (eight countries) performed CTP/CTA; 37 centres (11 countries) performed MRP/MRA.ParticipantsPatients aged over 18 years in whom brain scanning excluded intracranial haemorrhage, with known time of stroke onset and no clear indication for or contraindication to rt-PA, in whom treatment can start within 6 hours of a stroke.Interventionsrt-PA (0.9 mg/kg, maximum dose 90 mg) intravenously (10% bolus, the rest infused over 1 hour) compared with best medical care.Main outcome measuresPrimary – alive and independent (Oxford Handicap Score 0–2) at 6 months; secondary – symptomatic and fatal intracranial haemorrhage, early and late death. All imaging assessed centrally, blind to other data. Perfusion lesion sizes [cerebral blood volume (CBV); cerebral blood flow; mean transit time (MTT); time to maximum flow], angiographic occlusion, associations with plain scan findings, clinical baseline and outcomes, and the interaction with rt-PA were assessed with dichotomous and ordinal analyses.ResultsBaseline characteristics of patients in the Third International Stroke Trial (IST-3) with perfusion and angiography imaging did not differ from those without (95% did not meet the prevailing licence criteria for rt-PA): 151 patients had perfusion imaging and 423 had angiography (141 and 307 obtained at randomisation respectively). Most randomisation imaging was with CT (n = 125/141, 89% perfusion;n = 277/307, 90% angiography) with little MR (n = 16/141, 11% perfusion;n = 39/307, 10% angiography). The median patient age was 81 (interquartile range 71–86) years; perfusion imaging or angiography imaging was performed at median of 3.9 hours after stroke. Perfusion lesion size differed significantly between parameters (MTT lesions largest, CBV lesions smallest;p < 0.0000; 46% had mismatch). Patients scanned earlier, who were older, or with more severe stroke, had larger perfusion lesions. Larger perfusion lesions were associated with poor outcome. Neither perfusion lesion size nor mismatch modified rt-PA effect on haemorrhage or 6-month outcome. Randomisation CTA (n = 253) showed arterial stenosis/occlusion in 42% (95% confidence interval 34% to 47%). Abnormal plain CT and plain CT + CTA were equally associated with worse baseline stroke severity, imaging and functional outcomes. rt-PA accelerated dissolution of arterial thrombus and reduced thrombus extension, but rt-PA effects did not differ between patients with angiographic occlusion compared with those without.ConclusionLarger perfusion lesions and arterial occlusion are associated with severe stroke and worse outcomes. However, patients with perfusion lesions, mismatch or angiographic occlusion had similar benefit and no worse hazard from rt-PA compared with those without. Visual assessment is an effective classification method. Perfusion or angiography imaging may improve diagnostic confidence in acute stroke but this does not improve prediction of prognosis or identify patients who respond differently to rt-PA. Although this trial is larger than others, the conclusion regarding perfusion imaging is limited by the sample size.Trial registrationCurrent Controlled Trials ISRCTN25765518.FundingThis project was funded by the NIHR Efficacy and Mechanism Evaluation programme and the Medical Research Council, and will be published in full inEfficacy and Mechanism Evaluation; Vol. 1, No. 1. See the NIHR Journals Library website for further project information.

Effects of time on volume and distribution of coronary collateral flow

1976 ◽  
Vol 230 (2) ◽  
pp. 279-285 ◽  
Author(s):  
ML Marcus ◽  
RE Kerber ◽  
J Ehrhardt ◽  
FM Abboud
Keyword(s):  
Blood Flow ◽  
Vascular Resistance ◽  
Coronary Occlusion ◽  
Marked Decrease ◽  
Relative Proportion ◽  
Collateral Flow ◽  
Coronary Vascular Resistance ◽  
Collateral Blood Flow ◽  
Coronary Collateral Flow ◽  
Hemodynamic Measurements

Changes in the volume and distribution of collateral blood flow were studied during the 1st h after coronary occlusion in nine open-chest dogs. Labeled microspheres (7-10 mum) were injected into the left atrium prior to and 20 s, 5 min, and 60 min after acute occlusion of the midcircumflex coronary artery so that myocardial perfusion to small segments of the entire left ventricle could be measured. The segmental perfusions were classified as normally perfused, severely hypoperfused, moderately hypoperfused, and borderline hypoperfused. Standard hemodynamic measurements were obtained and relative coronary vascular resistance to the normally perfused and hypoperfused zones was calculated. The principal conclusions of the study are as follows: 1) during the 1st h after coronary occlusion the collateral flow to the hypoperfused myocardium increases substantially; 2) the increase in collateral flow is distributed fairly evenly to various hypoperfused zones and is associated with a marked decrease in coronary vascular resistance; and 3) as a result of this influx in collateral flow the size of the hypoperfused area decreases and the relative proportion of severely hypoperfused segments within the hypoperfused area decreases.

scholarly journals Relationship between haemodynamic impairment and collateral blood flow in carotid artery disease

2017 ◽  
Vol 38 (11) ◽  
pp. 2021-2032 ◽  
Author(s):  
Nolan S Hartkamp ◽  
Esben T Petersen ◽  
Michael A Chappell ◽  
Thomas W Okell ◽  
Maarten Uyttenboogaart ◽  
...  
Keyword(s):  
Blood Flow ◽  
Carotid Artery ◽  
Carotid Artery Disease ◽  
Tissue Level ◽  
Cerebrovascular Reactivity ◽  
Collateral Flow ◽  
Collateral Blood Flow ◽  
Ischaemic Damage ◽  
Before And After ◽  
Artery Disease

Collateral blood flow plays a pivotal role in steno-occlusive internal carotid artery (ICA) disease to prevent irreversible ischaemic damage. Our aim was to investigate the effect of carotid artery disease upon cerebral perfusion and cerebrovascular reactivity and whether haemodynamic impairment is influenced at brain tissue level by the existence of primary and/or secondary collateral. Eighty-eight patients with steno-occlusive ICA disease and 29 healthy controls underwent MR examination. The presence of collaterals was determined with time-of-flight, two-dimensional phase contrast MRA and territorial arterial spin labeling (ASL) imaging. Cerebral blood flow and cerebrovascular reactivity were assessed with ASL before and after acetazolamide. Cerebral haemodynamics were normal in asymptomatic ICA stenosis patients, as opposed to patients with ICA occlusion, in whom the haemodynamics in both hemispheres were compromised. Haemodynamic impairment in the affected brain region was always present in symptomatic patients. The degree of collateral blood flow was inversely correlated with haemodynamic impairment. Recruitment of secondary collaterals only occurred in symptomatic ICA occlusion patients. In conclusion, both CBF and cerebrovascular reactivity were found to be reduced in symptomatic patients with steno-occlusive ICA disease. The presence of collateral flow is associated with further haemodynamic impairment. Recruitment of secondary collaterals is associated with severe haemodynamic impairment.

Changes in the myocardial area at risk, infarct size, and collateral flow following nicardipine infusion in dogs

1991 ◽  
Vol 69 (12) ◽  
pp. 1789-1796
Author(s):  
Reena Sandhu ◽  
George P. Biro
Keyword(s):  
At Risk ◽  
Blood Flow ◽  
Infarct Size ◽  
Blue Dye ◽  
Collateral Flow ◽  
Collateral Blood Flow ◽  
Area At Risk ◽  
Arterial Blood ◽  
Myocardial Area ◽  
Size Limitation

The area at risk of infarction after an acute occlusion of the left anterior descending coronary artery was defined in anesthetized dogs using the distribution of 99mTc-labelled albumin microaggregates and Monastral blue dye. In thirteen dogs, it was determined that these two particulate labels identified identical areas of unperfused myocardium. In a second group of dogs (n = 12), the risk areas determined at 10 (99mTc-labelled macroaggregates) and at 180 min (Monastral blue dye) were found to be identical, with no change in collateral blood flow, indicating the absence of a spontaneous change in underperfused myocardium over this time. In a third group of dogs (n = 17) nicardipine was infused (10 μg∙kg−1∙min−1 for 5 min, followed by 8 μg∙kg−1∙min−1 for 165 min). This resulted in a significant and sustained fall (32 ± 4 mmHg; 1 mmHg = 133.32 Pa) in mean arterial blood pressure but no significant change in collateral blood flow was found, except for a marginal increase in the center of the ischemic zone. Area at risk and infarct sizes were also not significantly different between the latter two groups (18.2 ± 4.1 vs. 21.6 ± 4.0% of left ventricle). In this model, the magnitude of the area at risk appears to be determined early after a coronary occlusion and appears to be unmodified by treatment with nicardipine begun after the occlusion.Key words: area at risk, nicardipine, collateral flow, risk region, risk zone, infarct size limitation.

scholarly journals Clinical presentation and diffusion weighted MRI of acute cerebral infarction. The Bergen Stroke Study

BMC Neurology ◽  
2009 ◽  
Vol 9 (1) ◽  
Author(s):  
Halvor Naess ◽  
Jan C Brogger ◽  
Titto Idicula ◽  
Ulrike Waje-Andreassen ◽  
Gunnar Moen ◽  
...  
Keyword(s):  
Cerebral Infarction ◽  
Clinical Presentation ◽  
Acute Cerebral Infarction ◽  
Diffusion Weighted Mri ◽  
Diffusion Weighted ◽  
Stroke Study ◽  
And Diffusion

scholarly journals Ultrastructural assessment of myocardial necrosis occurring during ischemia and 3-h reperfusion in the dog

1999 ◽  
Vol 277 (1) ◽  
pp. H243-H252 ◽  
Author(s):  
Lewis C. Becker ◽  
Richmond W. Jeremy ◽  
Jutta Schaper ◽  
Wolfgang Schaper
Keyword(s):  
Electron Microscopy ◽  
Logistic Regression ◽  
Predictive Accuracy ◽  
Independent Predictor ◽  
Myocardial Necrosis ◽  
Collateral Flow ◽  
Collateral Blood Flow ◽  
Multiple Logistic Regression ◽  
Anesthetized Dogs ◽  
Irreversible Injury

To determine whether myocardial necrosis may occur during postischemic reperfusion, electron microscopy was used to identify morphological features of irreversible injury in myocardial samples taken from anesthetized dogs with 90-min ischemia and 0-, 5-, 90-, or 180-min reperfusion. In samples without detectable collateral blood flow, necrosis was almost complete, whether or not the myocardium was reperfused. In samples with collateral flow, necrosis was more frequent after 180-min reperfusion than in the absence of reperfusion, despite similar collateral flows in the two groups. Excess of necrosis after 180-min reperfusion was evident in endocardium (ischemia only: 4 of 13, 180-min reflow: 14 of 20; P = 0.03) and midwall (ischemia only: 9 of 25, 180-min reflow: 29 of 45; P = 0.02). Multiple logistic regression with variables of collateral flow and transmural position was used to determine risk of irreversible injury in 111 samples from ischemic myocardium without reperfusion (model predictive accuracy = 75%, P < 0.00001) and to predict risk of necrosis in myocardium reperfused for 180 min. Of 65 samples from endocardium and midwall with detectable collateral flow, the model predicted necrosis in 23 samples but necrosis was observed in 43 samples ( P < 0.01). Reperfusion duration was a determinant of frequency of irreversible injury. Multiple logistic regression for 186 samples from myocardium reperfused for 5, 90, or 180 min showed that reperfusion duration was an independent predictor of irreversible injury ( P = 0.0003) when collateral flow and transmural location were accounted for. These findings are consistent with the occurrence of necrosis during reperfusion in myocardium exposed to substantial, prolonged ischemia but with sufficient residual perfusion to avoid necrosis during the period of flow impairment.

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