Piers Klein

Mr. Piers Klein

orcid

Research Focus & Metrics

Academic Career Length

6Years (2021-Present)

(Calculated once Scilit publication data is synced: current year − year of first publication + 1)

Representative Publications

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1 March 2022 in Stroke
Verified
Journal Article
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PDF file
SYShadi Yaghi
Shadi Yaghi
LSLiqi Shu
Liqi Shu
EBEkaterina Bakradze
Ekaterina Bakradze
SOSetareh Salehi Omran
Setareh Salehi Omran
JGJames Anthony Giles
James Anthony Giles
KFKaren Furie
Karen Furie
Background: A small randomized controlled trial suggested that dabigatran may be as effective as warfarin in the treatment of cerebral venous thrombosis (CVT). We aimed to compare direct oral anticoagulants (DOACs) to warfarin in a real-world CVT cohort. Methods: This multicenter international retrospective study (United States, Europe, New Zealand) included consecutive patients with CVT treated with oral anticoagulation from January 2015 to December 2020. We abstracted demographics and CVT risk factors, hypercoagulable labs, baseline imaging data, and clinical and radiological outcomes from medical records. We used adjusted inverse probability of treatment weighted Cox-regression models to compare recurrent cerebral or systemic venous thrombosis, death, and major hemorrhage in patients treated with warfarin versus DOACs. We performed adjusted inverse probability of treatment weighted logistic regression to compare recanalization rates on follow-up imaging across the 2 treatments groups. Results: Among 1025 CVT patients across 27 centers, 845 patients met our inclusion criteria. Mean age was 44.8 years, 64.7% were women; 33.0% received DOAC only, 51.8% received warfarin only, and 15.1% received both treatments at different times. During a median follow-up of 345 (interquartile range, 140–720) days, there were 5.68 recurrent venous thrombosis, 3.77 major hemorrhages, and 1.84 deaths per 100 patient-years. Among 525 patients who met recanalization analysis inclusion criteria, 36.6% had complete, 48.2% had partial, and 15.2% had no recanalization. When compared with warfarin, DOAC treatment was associated with similar risk of recurrent venous thrombosis (aHR, 0.94 [95% CI, 0.51–1.73]; P =0.84), death (aHR, 0.78 [95% CI, 0.22–2.76]; P =0.70), and rate of partial/complete recanalization (aOR, 0.92 [95% CI, 0.48–1.73]; P =0.79), but a lower risk of major hemorrhage (aHR, 0.35 [95% CI, 0.15–0.82]; P =0.02). Conclusions: In patients with CVT, treatment with DOACs was associated with similar clinical and radiographic outcomes and favorable safety profile when compared with warfarin treatment. Our findings need confirmation by large prospective or randomized studies.

1 July 2023 in Stroke
Verified
Journal Article
Closed access
TNThanh N. Nguyen
Thanh N. Nguyen
MQMuhammad M. Qureshi
Muhammad M. Qureshi
DSDavide Strambo
Davide Strambo
DSDaniel Strbian
Daniel Strbian
SRSilja Räty
Silja Räty
SNSimon Nagel
Simon Nagel
BACKGROUND: The optimal management of patients with isolated posterior cerebral artery occlusion is uncertain. We compared clinical outcomes for endovascular therapy (EVT) versus medical management (MM) in patients with isolated posterior cerebral artery occlusion. METHODS: This multinational case-control study conducted at 27 sites in Europe and North America included consecutive patients with isolated posterior cerebral artery occlusion presenting within 24 hours of time last well from January 2015 to August 2022. Patients treated with EVT or MM were compared with multivariable logistic regression and inverse probability of treatment weighting. The coprimary outcomes were the 90-day modified Rankin Scale ordinal shift and ≥2-point decrease in the National Institutes of Health Stroke Scale. RESULTS: Of 1023 patients, 589 (57.6%) were male with median (interquartile range) age of 74 (64–82) years. The median (interquartile range) National Institutes of Health Stroke Scale was 6 (3–10). The occlusion segments were P1 (41.2%), P2 (49.2%), and P3 (7.1%). Overall, intravenous thrombolysis was administered in 43% and EVT in 37%. There was no difference between the EVT and MM groups in the 90-day modified Rankin Scale shift (aOR, 1.13 [95% CI, 0.85–1.50]; P =0.41). There were higher odds of a decrease in the National Institutes of Health Stroke Scale by ≥2 points with EVT (aOR, 1.84 [95% CI, 1.35–2.52]; P =0.0001). Compared with MM, EVT was associated with a higher likelihood of excellent outcome (aOR, 1.50 [95% CI, 1.07–2.09]; P =0.018), complete vision recovery, and similar rates of functional independence (modified Rankin Scale score, 0–2), despite a higher rate of SICH and mortality (symptomatic intracranial hemorrhage, 6.2% versus 1.7%; P =0.0001; mortality, 10.1% versus 5.0%; P =0.002). CONCLUSIONS: In patients with isolated posterior cerebral artery occlusion, EVT was associated with similar odds of disability by ordinal modified Rankin Scale, higher odds of early National Institutes of Health stroke scale improvement, and complete vision recovery compared with MM. There was a higher likelihood of excellent outcome in the EVT group despite a higher rate of symptomatic intracranial hemorrhage and mortality. Continued enrollment into ongoing distal vessel occlusion randomized trials is warranted.

1 December 2022 in Stroke
Verified
Journal Article
Closed access
PDF file
FSFatih Seker
Fatih Seker
MQMuhammad M. Qureshi
Muhammad M. Qureshi
MMMarkus A. Möhlenbruch
Markus A. Möhlenbruch
RNRaul G. Nogueira
Raul G. Nogueira
MAMohamad Abdalkader
Mohamad Abdalkader
SNSimon Nagel
Simon Nagel
Background: Reperfusion without functional independence (RFI) is an undesired outcome following thrombectomy in acute ischemic stroke. The primary objective was to evaluate, in patients presenting with proximal anterior circulation occlusion stroke in the extended time window, whether selection with computed tomography (CT) perfusion or magnetic resonance imaging is associated with RFI, mortality, or symptomatic intracranial hemorrhage (sICH) compared with noncontrast CT selected patients. Methods: The CLEAR study (CT for Late Endovascular Reperfusion) was a multicenter, retrospective cohort study of stroke patients undergoing thrombectomy in the extended time window. Inclusion criteria for this analysis were baseline National Institutes of Health Stroke Scale score ≥6, internal carotid artery, M1 or M2 segment occlusion, prestroke modified Rankin Scale score of 0 to 2, time-last-seen-well to treatment 6 to 24 hours, and successful reperfusion (modified Thrombolysis in Cerebral Infarction 2c–3). Results: Of 2304 patients in the CLEAR study, 715 patients met inclusion criteria. Of these, 364 patients (50.9%) showed RFI (ie, mRS score of 3–6 at 90 days despite successful reperfusion), 37 patients (5.2%) suffered sICH, and 127 patients (17.8%) died within 90 days. Neither imaging selection modality for thrombectomy candidacy (noncontrast CT versus CT perfusion versus magnetic resonance imaging) was associated with RFI, sICH, or mortality. Older age, higher baseline National Institutes of Health Stroke Scale, higher prestroke disability, transfer to a comprehensive stroke center, and a longer interval to puncture were associated with RFI. The presence of M2 occlusion and higher baseline Alberta Stroke Program Early CT Score were inversely associated with RFI. Hypertension was associated with sICH. Conclusions: RFI is a frequent phenomenon in the extended time window. Neither magnetic resonance imaging nor CT perfusion selection for mechanical thrombectomy was associated with RFI, sICH, and mortality compared to noncontrast CT selection alone. Registration: URL: https://www.clinicaltrials.gov ; Unique identifier: NCT04096248.

1 September 2022 in Stroke
Verified
Journal Article
Closed access
PDF file
MMMahmoud H. Mohammaden
Mahmoud H. Mohammaden
DHDiogo C. Haussen
Diogo C. Haussen
AAAlhamza R. Al-Bayati
Alhamza R. Al-Bayati
AHAmeer E. Hassan
Ameer E. Hassan
WTWondwossen Tekle
Wondwossen Tekle
RNRaul G. Nogueira
Raul G. Nogueira
Background: Successful reperfusion is one of the strongest predictors of functional outcomes after mechanical thrombectomy (MT). Despite continuous advancements in MT technology and techniques, reperfusion failure still occurs in ≈15% to 30% of patients with large vessel occlusion strokes undergoing MT. We aim to evaluate the safety and efficacy of rescue intracranial stenting for large vessel occlusion stroke after failed MT. Methods: The SAINT (Stenting and Angioplasty in Neurothrombectomy) Study is a retrospective analysis of prospectively collected data from 14 comprehensive stroke centers through January 2015 to December 2020. Patients were included if they had anterior circulation large vessel occlusion stroke due to intracranial internal carotid artery and middle cerebral artery-M1/M2 segments and failed MT. The cohort was divided into 2 groups: rescue intracranial stenting and failed recanalization (modified Thrombolysis in Cerebral Ischemia score 0–1). Propensity score matching was used to balance the 2 groups. The primary outcome was the shift in the degree of disability as measured by the modified Rankin Scale at 90 days. Secondary outcomes included functional independence (90-day modified Rankin Scale score 0–2). Safety measures included symptomatic intracranial hemorrhage and 90-day mortality. Results: A total of 499 patients were included in the analysis. Compared with the failed reperfusion group, rescue intracranial stenting had a favorable shift in the overall modified Rankin Scale score distribution (acOR, 2.31 [95% CI, 1.61–3.32]; P <0.001), higher rates of functional independence (35.1% versus 7%; adjusted odds ratio [aOR], 6.33 [95% CI, 3.14–12.76]; P <0.001), and lower mortality (28% versus 46.5%; aOR, 0.55 [95% CI, 0.31–0.96]; P =0.04) at 90 days. Rates of symptomatic intracerebral hemorrhage were comparable across both groups (7.1% versus 10.2%; aOR, 0.99 [95% CI, 0.42–2.34]; P =0.98). The matched cohort analysis demonstrated similar results. Specifically, rescue intracranial stenting (n=107) had a favorable shift in the overall modified Rankin Scale score distribution (acOR, 3.74 [95% CI, 2.16–6.57]; P <0.001), higher rates of functional independence (34.6% versus 6.5%; aOR, 10.91 [95% CI, 4.11–28.92]; P <0.001), and lower mortality (29.9% versus 43%; aOR, 0.49 [95% CI, 0.25–0.94]; P =0.03) at 90 days with similar rates of symptomatic intracerebral hemorrhage (7.5% versus 11.2%; aOR, 0.87 [95% CI, 0.31–2.42]; P =0.79) compared with patients who failed to reperfuse (n=107). There was no heterogeneity of treatment effect across the prespecified subgroups for improvement in functional outcomes. Conclusions: Acute intracranial stenting appears to be a safe and effective rescue strategy in patients with large vessel occlusion stroke who failed MT. Randomized multicenter trials are warranted.

1 June 2024 in European Stroke Journal
Verified
Journal Article
Closed access
Adam DmytriwAdam Dmytriw
Adam Dmytriw
BMBasel Musmar
Basel Musmar
Hamza A SalimHamza A Salim
Hamza A Salim
SGSherief Ghozy
Sherief Ghozy
JSJames E Siegler
James E Siegler
AGAdrien Guenego
Adrien Guenego
Background: Mechanical thrombectomy (MT) has revolutionized the treatment of acute ischemic stroke (AIS) due to large vessel occlusion (LVO), but its efficacy and safety in medium vessel occlusion (MeVO) remain less explored. This multicenter, retrospective study aims to investigate the incidence and clinical outcomes of vessel perforations (confirmed by extravasation during an angiographic series) during MT for AIS caused by MeVO. Methods: Data were collected from 37 academic centers across North America, Asia, and Europe between September 2017 and July 2021. A total of 1373 AIS patients with MeVO underwent MT. Baseline characteristics, procedural details, and clinical outcomes were analyzed. Results: The incidence of vessel perforation was 4.8% (66/1373). Notably, our analysis indicates variations in perforation rates across different arterial segments: 8.9% in M3 segments, 4.3% in M2 segments, and 8.3% in A2 segments (p = 0.612). Patients with perforation had significantly worse outcomes, with lower rates of favorable angiographic outcomes (TICI 2c-3: 23% vs 58.9%, p < 0.001; TICI 2b-3: 56.5% vs 88.3%, p < 0.001). Functional outcomes were also worse in the perforation group (mRS 0–1 at 3 months: 22.7% vs 36.6%, p = 0.031; mRS 0–2 at 3 months: 28.8% vs 53.9%, p < 0.001). Mortality was higher in the perforation group (30.3% vs 16.8%, p = 0.008). Conclusion: This study reveals that while the occurrence of vessel perforation in MT for AIS due to MeVO is relatively rare, it is associated with poor functional outcomes and higher mortality. The findings highlight the need for increased caution and specialized training in performing MT for MeVO. Further prospective research is required for risk mitigation strategies.

1 June 2024 in Stroke
Verified
Journal Article
Closed access
MMMahmoud H. Mohammaden
Mahmoud H. Mohammaden
LVLorena Souza Viana
Lorena Souza Viana
HAHend Abdelhamid
Hend Abdelhamid
MOMarta Olive-Gadea
Marta Olive-Gadea
MRMarc Rodrigo-Gisbert
Marc Rodrigo-Gisbert
RNRaul G. Nogueira
Raul G. Nogueira
BACKGROUND: Endovascular treatment (EVT) is part of the usual care for proximal vessel occlusion strokes. However, the safety and effectiveness of EVT for distal medium vessel occlusions remain unclear. We sought to compare the clinical outcomes of EVT to medical management (MM) for isolated distal medium vessel occlusions. METHODS: This is a retrospective analysis of prospectively collected data from seven comprehensive stroke centers. Patients were included if they had isolated distal medium vessel occlusion strokes due to middle cerebral artery M3/M4, anterior cerebral artery A2/A3, or posterior cerebral artery P1/P2 segments. Patients treated with EVT or MM were compared with multivariable logistic regression and inverse probability of treatment weighting. The primary outcome was the shift in the degree of disability as measured by the modified Rankin Scale (mRS) at 90 days. Secondary outcomes included 90-day good (mRS score, 0–2) and excellent (mRS score, 0–1) outcomes. Safety measures included symptomatic intracranial hemorrhage and 90-day mortality. RESULTS: A total of 321 patients were included in the analysis (EVT, 179; MM, 142; 40.8% treated with intravenous thrombolysis). In the inverse probability of treatment weighting model, there were no significant differences between EVT and MM in terms of the overall degree of disability (mRS ordinal shift; adjusted odds ratio [aOR], 1.25 [95% CI, 0.95–1.64]; P =0.110), rates of good (mRS score, 0–2; aOR, 1.32 [95% CI, 0.97–1.80]; P =0.075) and excellent (aOR, 1.32 [95% CI, 0.94–1.85]; P =0.098) outcomes, or mortality (aOR, 1.20 [95% CI, 0.78–1.85]; P =0.395) at 90 days. The multivariable regression model showed similar findings. Moreover, there was no difference between EVT and MM in rates of symptomatic intracranial hemorrhage in the multivariable regression model (aOR, 0.57 [95% CI, 0.21–1.58]; P =0.277), but the inverse probability of treatment weighting model showed a lower likelihood of symptomatic intracranial hemorrhage (aOR, 0.46 [95% CI, 0.24–0.85]; P =0.013) in the EVT group. CONCLUSIONS: This multicenter study failed to demonstrate any significant outcome differences among patients with isolated distal medium vessel occlusions treated with EVT versus MM. These findings reinforce clinical equipoise. Randomized clinical trials are ongoing and will provide more definite evidence.