P O Wester

Umeå University, Umeå, Västerbotten, Sweden

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Publications (253)1022.07 Total impact

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    ABSTRACT: Objective: We aimed to quantify the risk and predictors of ipsilateral ischemic stroke in patients with symptomatic carotid stenosis awaiting revascularization (carotid endarterectomy [CEA] or carotid artery stenting) by pooling individual patient data from recent prospective studies with high rates of treatment with modern stroke prevention medications. Methods: Data were included from 2 prospective hospital-based registries (Umeå, Barcelona) and one prospective population-based study (Dublin). Patients with symptomatic 50%-99% carotid stenosis eligible for carotid revascularization were included and followed for early recurrent ipsilateral stroke or retinal artery occlusion (RAO). Results: Of 607 patients with symptomatic 50%-99% carotid stenosis, 377 met prespecified inclusion criteria. Ipsilateral recurrent ischemic stroke/RAO risk pre-revascularization was 2.7% (1 day), 5.3% (3 days), 11.5% (14 days), and 18.8% (90 days). On bivariate analysis, presentation with a cerebral vs ocular event was associated with higher recurrent stroke risk (log-rank p = 0.04). On multivariable Cox regression, recurrence was associated with older age (adjusted hazard ratio [HR] per 10-year increase 1.5, p = 0.02) with a strong trend for association with cerebral (stroke/TIA) vs ocular symptoms (adjusted HR 2.7, p = 0.06), but not degree of stenosis, smoking, vascular risk factors, or medications. Conclusions: We found high risk of recurrent ipsilateral ischemic events within the 14-day time period currently recommended for CEA. Randomized trials are needed to determine the benefits and safety of urgent vs subacute carotid revascularization within 14 days after symptom onset.
    No preview · Article · Jan 2016 · Neurology
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    ABSTRACT: Background-Physical activity is of benefit for primary prevention of cardiovascular diseases, but it appears to increase the risk for atrial fibrillation. We aimed to study a cohort of patients following a first stroke in individuals with previous high physical activity, compare them to the general population with respect to recurrent stroke and death, and relate these to atrial fibrillation. Methods and Results-From the participants of the Vasaloppet, the world's largest ski-race, and matched individuals from the general population (n=708 604), we identified 5964 patients hospitalized with a first-time stroke between 1994 and 2010. Individuals with severe diseases were excluded. One half percent of skiers and 1% of nonskiers were hospitalized due to stroke. The incidence rate was 8.3 per 100 person-years among skiers and 11.1 among nonskiers. The hazard ratio (HR) for recurrent stroke or death between the 2 groups was 0.76 (95% CI 0.67 to 0.86). The result was consistent in subgroups. The HR for death was 0.66 (95% CI 0.56 to 0.78) and for recurrent stroke 0.82 (95% CI 0.70 to 0.96). After adjustment for smoking and socioeconomic factors, the HR for death was consistent at 0.70 (95% CI 0.56 to 0.87) while the HR for recurrent stroke was not statistically significant. Outcomes for skiers with atrial fibrillation tended to show a lower risk than for nonskiers. Conclusions-This large cohort study supports the hypothesis that patients with a stroke and with prior regular physical activity have a lower risk of death, while their risk for recurrent stroke is similar to that of nonskiers. The skiers had a higher incidence of atrial fibrillation, but still no increased risk of recurring stroke.
    Preview · Article · Oct 2015 · Journal of the American Heart Association
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    ABSTRACT: There is a growing awareness of the importance of carotid plaque features evaluation in stroke prediction. Carotid intima-media thickness (IMT) and recently its echogenicity were used for stroke prediction, although their clinical relevance was not well determined. The aim of this study was to assess the relationship between common carotid artery (CCA) ultrasound markers of atherosclerosis and distal, bifurcation and internal carotid artery (ICA), plaque features. We analyzed 137 carotid arteries in 87 asymptomatic patients with known carotid disease (mean age 69±6year, 34.5% females). Intima media thickness (IMT) and its gray scale median (IM-GSM) were measured at the CCA. Plaque textural features including gray scale median (GSM), juxtaluminal black area (JBA-mm(2)) without a visible cap, and plaque coarseness, at bifurcation and ICA were also determined. CCA measurements were correlated with those of the distal plaques. An increased IMT in CCA correlated with plaque irregularities in the bifurcation and ICA (r=0.53, p<0.001), while IM-GSM was closely related to plaque echogenicity (GSM) (r=0.76, p<0.001), and other textural plaque features. Both, IMT and IM-GSM correlated weakly with stenosis severity (r=0.27, p=0.001 and r=-0.18, p=0.026) respectively. In asymptomatic patients, measurements of CCA reflect distal, bifurcation and ICA disease, with IMT reflecting plaque irregularities and IM-GSM as markers of textural plaque abnormalities. Integrating measurements of both IMT and IM-GSM in a model could be used as a better marker of disease vulnerability over and above each measure individually. Copyright © 2015 Elsevier Ireland Ltd. All rights reserved.
    No preview · Article · Oct 2015 · International journal of cardiology
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    ABSTRACT: Background and aim: Arterial calcification is often detected on ultrasound examination but its diagnostic accuracy is not well validated. The aim of this study was to determine the accuracy of carotid ultrasound B mode findings in detecting atherosclerotic calcification quantified by cone beam computed tomography (CBCT). Methods: We analyzed 94 carotid arteries, from 88 patients (mean age 70 ± 7 years, 33% females), who underwent pre-endarterectomy ultrasound examination. Plaques with high echogenic nodules and posterior shadowing were considered calcified. After surgery, the excised plaques were examined using CBCT, from which the calcification volume (mm3) was calculated. In cases with multiple calcifications the largest calcification nodule volume was used to represent the plaque. Carotid artery calcification by the two imaging techniques was compared using conventional correlations. Results: Carotid ultrasound was highly accurate in detecting the presence of calcification; with a sensitivity of 88.2%. Based on the quartile ranges of calcification volumes measured by CBCT we have divided plaque calcification into four groups: <8; 8-35; 36-70 and >70 mm3. Calcification volumes ≥8 were accurately detectable by ultrasound with a sensitivity of 96%. Of the 21 plaques with <8 mm3 calcification volume; only 13 were detected by ultrasound; resulting in a sensitivity of 62%. There was no difference in the volume of calcification between symptomatic and asymptomatic patients. Conclusion: Carotid ultrasound is highly accurate in detecting the presence of calcified atherosclerotic lesions of volume ≥8 mm3; but less accurate in detecting smaller volume calcified plaques. Further development of ultrasound techniques should allow better detection of early arterial calcification.
    Full-text · Article · Aug 2015 · International Journal of Molecular Sciences
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    ABSTRACT: The aim of this study was to determine whether people with calcifications in the area of the carotid arteries on panoramic radiographs (CALPANs) have an increased prevalence of vascular risk factors or an increased risk of future vascular events. We included 113 consecutive patients with CALPANs and 116 gender- and age-matched controls without CALPANs. Vascular risk factors were generally known in the study population, since it was recorded in a population-based community-screening program. Patients with CALPANs had a higher prevalence of vascular risk factors than controls independent of previous vascular events. During the 5.4-year follow-up, patients with CALPANs had a higher risk of a combined endpoint of vascular events (5.6%/yr) compared with the controls (2.4%/yr) (P = .004 by log rank test; unadjusted hazard ratio (HR) 2.4; 95% CI 1.3-4.3). This difference was not significant when previous vascular events and risk factors were taken into account (adjusted HR; 1.2; 95% CI 0.6-2.3; P = .62; Cox regression). People with CALPANs are very likely to have vascular risk factors, but these factors might be unknown when CALPANs are detected. Accordingly, patients with CALPANs should be advised to have their vascular risk factors regularly checked in order to receive advice on preventive lifestyle modifications and medical treatment when indicated. However, it remains unknown whether CALPANs add information about the independent risk of future vascular events. Therefore, further studies are warranted to investigate whether the detection of CALPANs indicates a need for additional or more intense vascular treatment. Copyright © 2015 Elsevier Inc. All rights reserved.
    No preview · Article · Jul 2015

  • No preview · Article · Jul 2015 · Atherosclerosis

  • No preview · Article · Jul 2015 · Atherosclerosis
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    ABSTRACT: Abstract Objective: To evaluate in a systematic review and meta-analysis model the effect of statin therapy on carotid plaque echogenicity assessed by ultrasound. Methods: We have systematically searched electronic databases (PubMed, MEDLINE, EMBASE and Cochrane Center Register) up to April, 2015, for studies evaluating the effect of statins on plaque echogenicity. Two researchers independently determined the eligibility of studies evaluating the effect of statin therapy on carotid plaque echogenicity that used ultrasound and grey scale median (GSM) or integrated back scatter (IBS). Results: Nine out of 580 identified studies including 566 patients’ carotid artery data were meta-analyzed for a mean follow up of 7.2 months. A consistent increase in the echogenicity of carotid artery plaques, after statin therapy, was reported. Pooled weighted mean difference % (WMD) on plaque echogenicity after statin therapy was 29% (95% CI 22%–36%), p < 0.001, I2 = 92.1%. In a meta-regression analysis using % mean changes of LDL, HDL and hsCRP as moderators, it was shown that the effects of statins on plaque echogenicity were related to changes in hsCRP, but not to LDL and HDL changes from the baseline. The effect of statins on the plaque was progressive; it showed significance after the first month of treatment, and the echogenicity continued to increase in the following six and 12 months. Conclusions: Statin therapy is associated with a favorable increase of carotid plaque echogenicity. This effect seems to be dependent on the period of treatment and hsCRP change from the baseline, independent of changes in LDL and HDL.
    No preview · Article · May 2015 · International Journal of Molecular Sciences

  • No preview · Article · Apr 2015 · International Journal of Stroke
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    ABSTRACT: To determine calcium volume in extirpated carotid plaques, analyze correlations between calcium volume and degree of stenosis, and analyze whether calcium volume influences the possibility of detecting stenosis in panoramic radiographs. Ninety-seven consecutive patients with ultrasonography-verified carotid stenosis were examined with panoramic radiography before surgery. Extirpated carotid plaques (n = 103) were analyzed for calcium volume by cone beam computed tomography (CBCT). Panoramic radiographs were analyzed for carotid calcifications. The median calcium volume was 45 mm(3) (first quartile subtracted from the third quartile [IQR], 14-98 mm(3)). We observed no correlation between calcium volume and degree of stenosis. Seventy-eight stenoses were situated within the region included in the panoramic radiographs, and their volumes ranged from 0 to 509 mm(3). Of these, 99% revealed carotid calcifications on panoramic radiographs. We found no association between calcium volume and degree of carotid stenosis. Calcium volume did not influence the possibility of detecting carotid calcifications in panoramic radiographs. Copyright © 2015 Elsevier Inc. All rights reserved.
    No preview · Article · Apr 2015
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    ABSTRACT: In many countries, including Sweden, initiatives have been taken to reduce between-hospital differences in the quality of stroke services. We have explored to what extent hospital type (university, specialized nonuniversity, or community hospital) influences hospital performance. Riksstroke collects clinical data during hospital stay (national coverage 94%). Follow-up data at 3 months were collected using administrative registers and a questionnaire completed by surviving patients (response rate 88%). Structural data were collected from a questionnaire completed by hospital staff (response rate 100%). Multivariate analyses with adjustment for clustering were used to test differences between types of hospitals. The proportion of patients admitted directly to a stroke unit was highest in community hospitals and lowest in university hospitals. Magnetic resonance, carotid imaging, and thrombectomy were more frequently performed in university hospitals, and the door-to-needle time for thrombolysis was shorter. Secondary prevention with antihypertensive drugs was used less often, and outpatient follow-up was less frequent in university hospitals. Fewer patients in community hospitals were dissatisfied with their rehabilitation. After adjusting for possible confounders, poor outcome (dead or activities of daily living dependency 3 months after stroke) was not significantly different between the 3 types of hospital. In a setting with national stroke guidelines, stroke units in all hospitals, and measurement of hospital performance and benchmarking, outcome (after case-mix adjustment) is similar in university, specialized nonuniversity, and community hospitals. There seems to be fewer barriers to organizing well-functioning stroke services in community hospitals compared with university hospitals. © 2015 American Heart Association, Inc.
    No preview · Article · Feb 2015 · Stroke
  • Thomas Gu · Per Wester · Elias Johansson
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    ABSTRACT: Intravenous thrombolysis has been a break-through for treatment of acute ischemic stroke. However, total recanalization is only achieved in 18%. Sonothrombolysis aims at enhancing the recanalization effect by adding continuous transcranial ultrasound. Sonothrombolysis may facilitate the recanalization rate without increased risk of intracerebral hemorrhage. This further results in decreased risk of disability compared with only intravenous thrombolysis. Intravenously applied micro-bubbles is an additive treatment to sonothrombolysis which might further increase the recanalization rate but perhaps at the expense of increased risk of intracerebral hemorrhage. In a case-series at Umeå Stroke Center, we report the results of the first 20 ischemic stroke patients treated with sonothrombolysis in Sweden. Our initial results look promising with recanalization rates similar to earlier published data. No intracerebral hemorrhage occurred among our sonothrombolysed patients.
    No preview · Article · Feb 2015 · Lakartidningen
  • T. Gu · P. Wester · E. Johansson
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    ABSTRACT: Intravenous thrombolysis has been a break-through for treatment of acute ischemic stroke. However, total recanalization is only achieved in 18%. Sonothrombolysis aims at enhancing the recanalization effect by adding continuous transcranial ultrasound. Sonothrombolysis may facilitate the recanalization rate without increased risk of intracerebral hemorrhage. This further results in decreased risk of disability compared with only intravenous thrombolysis. Intravenously applied micro-bubbles is an additive treatment to sonothrombolysis which might further increase the recanalization rate but perhaps at the expense of increased risk of intracerebral hemorrhage. In a case- series at Umeå Stroke Center, we report the results of the first 20 ischemic stroke patients treated with sonothrombolysis in Sweden. Our initial results look promising with recanalization rates similar to earlier published data. No intracerebral hemorrhage occurred among our sonothrombolysed patients.
    No preview · Article · Jan 2015 · Lakartidningen
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    ABSTRACT: Introduction: Among patients with unexplained dyspnea, left ventricular (LV) filling pressures (LVFP) is commonly estimated non-invasively by the E/e' ratio using Doppler echocardiography. However the accuracy of E/e' is controversial. We evaluated the correlation of E/e' ratio with invasively measured LVFP and of change in E/e' (ΔE/e') with change in LVFP. Methods: Supine and upright transthoracic echocardiography was performed in patients with unexplained dyspnea undergoing right heart catheterization. Patients with significant valvular disease and reduced LV ejection fraction (LVEF < 50%) were excluded. Pulmonary artery wedge pressure (PAWP) was used as the invasive indicator of LVFP. The mean of septal and lateral e' velocities was used for the calculation of E/e' ratio. Results: We studied 98 subjects with a mean age of 52 ± 20 years (69% of female gender). The supine E/e' and PAWP were 9.2 ± 3.2 and 12.1 ± 4.9 mmHg (range: 4-27 mmHg) respectively and were modestly correlated (r=0.38; p<0.001). With position change (supine to upright), ΔPAWP was -5.1 ± 4.3 mmHg and ΔE/e' was 0.17 ± 2.6, with no significant association between these two measures (r=0.003; p=0.98). Both E-wave (80 ± 22 to 65 ± 22 cm/s) and mean average e' (10.2 ± 3.6 to 7.3 ± 2.0 cm/s) decreased with the upright position. The ΔPAWP was correlated with ΔE-wave velocity (r=0.33; p=0.01), but not with Δe' (r=0.14; p=0.26). Conclusions: In patients with unexplained dyspnea and a preserved LVEF, E/e' is modestly, though significantly, correlated with PAWP. ΔE/e' is not correlated with ΔPAWP, partially related to the preload sensitivity of e'.
    No preview · Conference Paper · Dec 2014
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    Elias Johansson · Jakob Bjellerup · Per Wester
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    ABSTRACT: Background Although it is preferable that all patients with a recent Transient Ischemic Attack (TIA) undergo acute carotid imaging, there are centers with limited access to such acute examinations. It is controversial whether ABCD2 or ABCD3 scores can be used to triage patients to acute or delayed carotid imaging. It would be acceptable that some patients with a symptomatic carotid stenosis are detected with a slight delay as long as those who will suffer an early recurrent stroke are detected within 24 hours. The aim of this study is to analyze the ability of ABCD2 and ABCD3 scores to predict ipsilateral ischemic stroke among patients with symptomatic 50-99% carotid stenosis.Methods In this secondary analysis of the ANSYSCAP-study, we included 230 consecutive patients with symptomatic 50-99% carotid stenosis. We analyzed the risk of recurrent ipsilateral ischemic stroke before carotid endarterectomy based on each parameter of the ABCD2 and ABCD3 scores separately, and for total ABCD2 and ABCD3 scores. We used Kaplan-Meier analysis.ResultsNone of the parameters in the ABCD2 or ABCD3 scores could alone predict all 12 of the ipsilateral ischemic strokes that occurred within 2 days of the presenting event, but clinical presentation tended to be a statistically significant risk factor for recurrent ipsilateral ischemic stroke (p¿=¿0.06, log rank test). An ABCD2 score ¿2 and an ABCD3 score ¿4 could predict all 12 of these strokes as well as all 25 ipsilateral ischemic strokes that occurred within 14 days. To use ABCD3 score seems preferable over the ABCD2 score because a higher proportion of low risk patients were identified (17% of the patients had an ABCD3 score <4 while only 6% had an ABCD2¿<¿2).Conclusions Although it is preferable that carotid imaging be performed within 24 hours, our data support that an ABCD3 score ¿4 might be used for triaging patients to acute carotid imaging in clinical settings with limited access to carotid imaging. However, our findings should be validated in a larger cohort study.
    Preview · Article · Nov 2014 · BMC Neurology
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    Dataset: 513.full

    Full-text · Dataset · Oct 2014
  • Elias Johansson · Kjell Öhman · Per Wester
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    ABSTRACT: Background The risk of early stroke recurrence among patients with symptomatic carotid near-occlusion with and without full collapse is unknown. Therefore the aim of this study was to analyse the 90-day risk of recurrent ipsilateral ischaemic stroke in patients with symptomatic carotid near-occlusion both with and without full collapse.Methods This study was a secondary analysis of the Additional Neurological SYmptoms before Surgery of the Carotid Arteries: a Prospective study (ANSYSCAP). We prospectively analysed 230 consecutive patients with symptomatic 50–99% carotid stenosis or near-occlusion. Based on the combination of several imaging modalities, 205 (89%) patients were classified as having 50–99% carotid stenosis, and 10 (4%) and 15 (7%) as having near-occlusion with and without full collapse, respectively. The 90-day risk of recurrent ipsilateral ischaemic stroke was compared between these three groups. Only events that occurred before carotid endarterectomy were analysed.ResultsThe 90-day risk of recurrent stroke was 18% [95% confidence interval (CI) 12–25%; n = 29] for patients with 50–99% carotid stenosis, 0% for patients with near-occlusion without full collapse and 43% (95% CI 25–89%; n = 4) for patients with near-occlusion with full collapse (P = 0.035, log rank test). The increased risk of recurrent ipsilateral ischaemic stroke for patients with symptomatic near-occlusion with full collapse remained significant after multivariable adjustment for age, sex and type of presenting event.Conclusions Patients with symptomatic carotid near-occlusion with full collapse might have a very high risk of stroke recurrence. Carotid endarterectomy could be considered for these patients.This article is protected by copyright. All rights reserved.
    No preview · Article · Oct 2014 · Journal of Internal Medicine
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    ABSTRACT: Background and Aim: Arterial calcification is often detected on ultrasound examination, the diagnostic accuracy of which is not well validated. The aim of this study was to determine the accuracy of carotid ultrasound B mode findings in detecting atherosclerotic calcification as compared with cone beam CT (CBCT). Methods: We analyzed 98 carotid arteries, from 92 patients who underwent pre-endarterectomy ultrasound examination. Plaques with high echogeneic nodules and posterior shadowing were considered calcified. After surgery, the removed plaques were examined using CBCT, from which the calcification volume (mm3) was calculated. Carotid artery calcification by the two imaging techniques was compared using conventional correlations. Results: Carotid ultrasound was highly accurate in detecting the presence of calcification, with a specificity of 100% and sensitivity of 91.7%, p=0.007, having an area under the ROC curve (AUC) of 85% (95% CI=0.75-0.95), p<0.001. Using ROC analysis, a cut-off value of 14mm3 was determined. Carotid ultrasound sensitivity in detecting a calcification volume of ≥14 mm3 was 96.1% and specificity was 100%. Of the 21 plaques with a 1-14mm3 calcification, only 13 were detected by ultrasound, resulting in a sensitivity of 61.9%, with p=0.219. Conclusion: Carotid ultrasound is highly accurate in detecting the presence of calcified atherosclerotic lesions of volume more than 14 mm3. However it was less accurate in detecting small volume calcified plaques, with a relatively high false negativity.
    No preview · Conference Paper · Sep 2014
  • Elias Johansson · Thomas Gu · Per Wester
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    ABSTRACT: In populations with a high (≥14) median National Institute of Health Stroke Score (NIHSS), a normal finding of Thrombolysis in Brain Ischemia grade 5 (TIBI 5) in the artery of interest has been reported to be an unusual finding when transcranial ultrasound is performed during thrombolysis. In such instances, a stroke mimic can be suspected, but there are alternative pathophysiological explanations. In this case series, the median NIHSS was relatively low (5), and 33% (6/18) of the patients treated with thrombolysis had TIBI 5 in the artery of interest at the time of treatment initiation. These 6 patients had normal findings on the computerized tomography angiography. Only 33% (2/6) of these patients were stroke mimics, the remaining had either lacunar (n = 2) or cortical strokes (n = 2). These cortical stroke patients probably had a pretreatment recanalization marked by partial symptom regression before treatment onset. Compared to patients with TIBI <5 at baseline, the patients with TIBI 5 at baseline tended to be younger (p = 0.19, Mann-Whitney test) and more often have lacunar syndrome (p = 0.18, χ(2) test). Thus, among patients treated with thrombolysis and with a low median NIHSS, a finding of TIBI 5 is not unusual. This does not mean that the patient has a stroke mimic per se, and it tends to be more common among patients with lacunar syndrome than among patients with cortical syndromes.
    No preview · Article · Aug 2014
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    ABSTRACT: Background and aim: Carotid plaques may represent a generalized atherosclerotic syndrome or a localized disease. The aim of this study was to assess the morphological and textural features of carotid plaques located contralateral to the symptomatic side and compare them with the symptomatic side and with plaques from asymptomatic patients. Methods: We studied 66 arteries in 39 patients (mean age 70 ± 7 year, 33% females). Arterial plaques were classified as either symptomatic (n = 30), contralateral to symptomatic (n = 25) or asymptomatic (n = 11). We compared several plaque features between these groups including the mean values of the grey scale median (GSM), entropy, juxtaluminal black area (JBA) without visible echogenic cap, GSM of the JBA and surface irregularity. Results: The plaques contralateral to symptomatic arteries had similar morphological and textural features to those in the symptomatic arteries. In contrast, they had more vulnerable morphological and textural features than those in asymptomatic arteries: less smooth plaques (12% vs. 55%) and instead more often mildly irregular (60% vs 36%) or markedly irregular (28% vs. 9%; p = 0.03), lower GSM (26.2 ± 8 vs. 49.4 ± 14, p < 0.001) and lower GSM of the JBA (5.0 ± 3.6 vs. 11.4 ± 2.1, p = 0.008). The frequency of entropy and plaque calcification was similar in all groups. Conclusion: Symptomatic patients with carotid artery disease seem to have similar morphological and textural features of vulnerability in the symptomatic and the contralateral carotid arteries, which are profound compared with asymptomatic carotid arteries. These findings support the concept of generalized carotid atherosclerotic pathology rather than incidental unilateral disease, and also emphasize a need for aggressive measures for plaque stabilization, particularly in symptomatic patients.
    No preview · Article · Jun 2014 · Atherosclerosis

Publication Stats

10k Citations
1,022.07 Total Impact Points

Institutions

  • 1978-2015
    • Umeå University
      • Department of Public Health and Clinical Medicine
      Umeå, Västerbotten, Sweden
  • 1973-2009
    • Stockholm University
      Tukholma, Stockholm, Sweden
  • 2008
    • Public Health Agency of Sweden
      Tukholma, Stockholm, Sweden
  • 2005
    • Landstinget i Uppsala Iän
      Uppsala, Uppsala, Sweden
  • 2004
    • Norrlands universitetssjukhus
      Umeå, Västerbotten, Sweden
  • 2003
    • National Public Health Institute
      Helsinki, Southern Finland Province, Finland
  • 1995
    • University of Miami
      • Department of Neurology
      كورال غيبلز، فلوريدا, Florida, United States
  • 1988-1993
    • University of Gothenburg
      Goeteborg, Västra Götaland, Sweden
  • 1992
    • George Washington University
      • Department of Medicine
      Washington, Washington, D.C., United States
  • 1980
    • Mid Sweden University
      Härnösand, Västernorrland, Sweden
  • 1965-1977
    • Karolinska Institutet
      • Department of Medicine, Huddinge
      Сольна, Stockholm, Sweden