Rachael MacIsaac

Allopurinol and Cardiovascular Outcomes in Adults With Hypertension

Allopurinol lowers blood pressure in adolescents and has other vasoprotective effects. Whether similar benefits occur in older individuals remains unclear. We hypothesized that allopurinol is associated with improved cardiovascular outcomes in older adults with hypertension. Data from the United Kingdom Clinical Research Practice Datalink were used. Multivariate Cox-proportional hazard models were applied to estimate hazard ratios for stroke and cardiac events (defined as myocardial infarction or acute coronary syndrome) associated with allopurinol use over a 10-year period in adults aged >65 years with hypertension. A propensity-matched design was used to reduce potential for confounding. Allopurinol exposure was a time-dependent variable and was defined as any exposure and then as high (≥300 mg daily) or low-dose exposure. A total of 2032 allopurinol-exposed patients and 2032 matched nonexposed patients were studied. Allopurinol use was associated with a significantly lower risk of both stroke (hazard ratio, 0.50; 95% confidence interval, 0.32–0.80) and cardiac events (hazard ratio, 0.61; 95% confidence interval, 0.43–0.87) than nonexposed control patients. In exposed patients, high-dose treatment with allopurinol (n=1052) was associated with a significantly lower risk of both stroke (hazard ratio, 0.58; 95% confidence interval, 0.36–0.94) and cardiac events (hazard ratio, 0.65; 95% confidence interval, 0.46–0.93) than low-dose treatment (n=980). Allopurinol use is associated with lower rates of stroke and cardiac events in older adults with hypertension, particularly at higher doses. Prospective clinical trials are needed to evaluate whether allopurinol improves cardiovascular outcomes in adults with hypertension.

Clinical Selection Strategies to Identify Ischemic Stroke Patients With Large Anterior Vessel Occlusion: Results From SITS-ISTR (Safe Implementation of Thrombolysis in Stroke International Stroke Thrombolysis Registry).

Background and Purpose— The National Institutes of Health Stroke Scale (NIHSS) correlates with presence of large anterior vessel occlusion (LAVO). However, the application of the full NIHSS in the prehospital setting to select patients eligible for treatment with thrombectomy is limited. Therefore, we aimed to evaluate the prognostic value of simple clinical selection strategies. Methods— Data from the Safe Implementation of Thrombolysis in Stroke International Stroke Thrombolysis Registry (January 2012–May 2014) were analyzed retrospectively. Patients with complete breakdown of NIHSS scores and documented vessel status were included. We assessed the association of prehospital stroke scales and NIHSS symptom profiles with LAVO (internal carotid artery, carotid-terminus or M1-segment of the middle cerebral artery). Results— Among 3505 patients, 23.6% (n=827) had LAVO. Pathological finding on the NIHSS item best gaze was strongly associated with LAVO (adjusted odds ratio 4.5, 95% confidence interval 3.8–5.3). All 3 face–arm–speech–time test (FAST) items identified LAVO with high sensitivity. Addition of the item best gaze to the original FAST score (G-FAST) or high scores on other simplified stroke scales increased specificity. The NIHSS symptom profiles representing total anterior syndromes showed a 10-fold increased likelihood for LAVO compared with a nonspecific clinical profile. If compared with an NIHSS threshold of ≥6, the prehospital stroke scales performed similarly or even better without losing sensitivity. Conclusions— Simple modification of the face–arm–speech–time score or evaluating the NIHSS symptom profile may help to stratify patients’ risk of LAVO and to identify individuals who deserve rapid transfer to comprehensive stroke centers. Prospective validation in the prehospital setting is required.

Tenecteplase versus alteplase in stroke thrombolysis: An individual patient data meta-analysis of randomized controlled trials:

Background Tenecteplase, a modified plasminogen activator with higher fibrin specificity and longer half-life, may have advantages over alteplase in acute ischemic stroke thrombolysis. Aims We undertook an individual patient data meta-analysis of randomized controlled trials that compared alteplase with tenecteplase in acute stroke. Methods Eligible studies were identified by a MEDLINE search, and individual patient data were acquired. We compared clinical outcomes including modified Rankin Scale at three months, early neurological improvement at 24 h, intracerebral hemorrhage, symptomatic intracerebral hemorrhage, and mortality at three months between all dose tiers of tenecteplase and alteplase. Results Three relevant studies (Haley et al., Parsons et al., and ATTEST) included 291 patients and investigated three doses of tenecteplase (0.1, 0.25, 0.4 mg/kg). There were no differences between any dose of tenecteplase and alteplase for either efficacy or safety end points. Tenecteplase 0.25 mg/kg had the greatest odds to achieve early neurological improvement (OR [95%CI] 3.3 [1.5, 7.2], p = 0.093), excellent functional outcome (modified Rankin Scale 0–1) at three months (OR [95%CI] 1.9 [0.8, 4.4], p = 0.28), with reduced odds of intracerebral hemorrhage (OR [95%CI] 0.6 [0.2, 1.8], P = 0.43) compared with alteplase. Only 19 patients were treated with tenecteplase 0.4 mg/kg, which showed increased odds of symptomatic intracerebral hemorrhage compared with alteplase (OR [95% CI] 6.2 [0.7, 56.3]). Conclusions While no significant differences between tenecteplase and alteplase were found, point estimates suggest potentially greater efficacy of 0.25 and 0.1 mg/kg doses with no difference in symptomatic intracerebral hemorrhage, and potentially higher symptomatic intracerebral hemorrhage risk with the 0.4 mg/kg dose. Further investigation of 0.25 mg/kg tenecteplase is warranted.

Statins and risk of poststroke hemorrhagic complications

Objective: To assess whether statin treatment before or after acute ischemic stroke (AIS) affects the risk of acute intracerebral hemorrhage (ICH), postacute ICH, and mortality within 90 days. Methods: Data were sought from the Virtual International Stroke Trials Archive, an international repository of clinical trials data. Using propensity score matching, we retrospectively compared patients with prior statin treatment and newly initiated statin within 3 days after AIS to patients without statin exposure. Outcomes of interest were acute symptomatic ICH (sICH), any acute ICH, postacute ICH, and mortality during follow-up of 3 months. Results: A total of 8,535 patients (mean age 70 years, 54% male, median baseline NIH Stroke Scale score 13) were analyzed. After propensity score matching, prior statin use was not strongly associated with sICH (adjusted odds ratio [OR] 1.33, 95% confidence interval [CI] 0.83–2.14) or any ICH (adjusted OR 1.35, 95% CI 0.92–1.98). There was no evidence of an interaction between prior statin use and thrombolysis. New initiation of statins was not associated with postacute ICH (adjusted hazard ratio [HR] 1.60, 95% CI 0.70–3.65). There was a signal towards lower 90-day mortality in patients with prior statin use (adjusted HR 0.84, 95% CI 0.70–1.00) and especially early initiation of statins (adjusted HR 0.67, 95% CI 0.46–0.97). Conclusions: Statin use prior to AIS was not associated with early hemorrhagic complications, irrespective of treatment with thrombolysis. New initiation of statin treatment early after AIS did not affect risk of postacute ICH, but might be associated with reduced mortality.

Risk of stroke in chronic heart failure patients with preserved ejection fraction, but without atrial fibrillation: analysis of the CHARM-Preserved and I-Preserve trials

Aims The incidence and predictors of stroke in patients with heart failure and preserved ejection fraction (HF-PEF), but without atrial fibrillation (AF), are unknown. We described the incidence of stroke in HF-PEF patients with and without AF and predictors of stroke in those without AF. Methods and results We pooled data from the CHARM-Preserved and I-Preserve trials. Using Cox regression, we derived a model for stroke in patients without AF in this cohort and compared its performance with a published model in heart failure patients with reduced ejection fraction (HF-REF)—predictive variables: age, body mass index, New York Heart Association class, history of stroke, and insulin-treated diabetes. The two stroke models were compared and Kaplan–Meier curves for stroke estimated. The risk model was validated in a third HF-PEF trial. Of the 6701 patients, 4676 did not have AF. Stroke occurred in 124 (6.1%) with AF and in 171 (3.7%) without AF (rates 1.80 and 1.00 per 100 patient-years, respectively). There was no difference in performance of the stroke model derived in the HF-PEF cohort and the published HF-REF model (c-index 0.71, 95% confidence interval 0.57–0.84 vs. 0.73, 0.59–0.85, respectively) as the predictive variables overlapped. The model performed well in the validation cohort (0.86, 0.62–0.99). The rate of stroke in patients in the upper third of risk approximated to that in patients with AF (1.60 and 1.80 per 100 patient-years, respectively). Conclusions A small number of clinical variables identify a subset of patients with HF-PEF, but without AF, at elevated risk of stroke.

Interaction of Recanalization, Intracerebral Hemorrhage, and Cerebral Edema After Intravenous Thrombolysis

Background and Purpose— Both intracerebral hemorrhage (ICH) and brain edema have been attributed to reperfusion after intravenous thrombolysis. We explored the interaction of recanalization and core size for imaging outcomes (ICH and vasogenic brain edema). Methods— In patients with anterior circulation occlusion given intravenous thrombolysis <4.5 hours and imaged with computed tomographic (CT) perfusion and CT angiography, we defined volumes of core (relative delay time >2 s and relative cerebral blood flow <40%) and penumbra (relative delay time >2 s). CT and CT angiography at 24 hours were reviewed for ICH (European Cooperative Acute Stroke Study [ECASS]-2 definition), early vasogenic edema (third International Stroke Trial [IST-3] criteria), and recanalization (thrombolysis in myocardial infarction 2–3). Independent effects of recanalization, core volume and potential interactions on edema, ICH and day 90 outcomes were estimated by logistic regression. Results— In 123 patients, there was a trend for recanalization to be associated with H1/2 ICH (odds ratio [OR], 2.3 [0.97–5.5]; P=0.06) but not with PH1/2 ICH (OR, 1.7 [0.33–8.8]; P=0.5), any edema, or significant brain edema (OR, 1.45 [0.4–4.9]; P=0.55). Ischemic core (>50 mL) was associated with any ICH (OR, 4.0 [1.6–9.5]; P=0.003), edema (OR, 5.4 [2–14]; P<0.01), and significant brain edema (OR, 17.4 [5.3–57]; P<0.01) but not with PH1/2 ICH (OR, 1.2 [0.23–6.5]; P=0.8), after controlling for recanalization. There was no significant interaction of recanalization and large core for any adverse outcomes. Conclusions— Large ischemic core was associated with poorer outcomes and both early vasogenic brain edema and ICH, but recanalization on 24-hour CT angiography was associated with clinically favorable outcome. There was no significant interaction of recanalization and large core volume for any outcomes. The association of hemorrhage or brain edema with post-thrombolysis reperfusion is unclear.

A collaborative sequential meta-analysis of individual patient data from randomized trials of endovascular therapy and tPA vs. tPA alone for acute ischemic stroke: ThRombEctomy And tPA (TREAT) analysis: statistical analysis plan for a sequential meta-analysis performed within the VISTA-Endovascular collaboration.

Rationale Endovascular treatment has been shown to restore blood flow effectively. Second-generation medical devices such as stent retrievers are now showing overwhelming efficacy in clinical trials, particularly in conjunction with intravenous recombinant tissue plasminogen activator. Aims and Design This statistical analysis plan utilizing a novel, sequential approach describes a prospective, individual patient data analysis of endovascular therapy in conjunction with intravenous recombinant tissue plasminogen activator agreed upon by the Thrombectomy and Tissue Plasminogen Activator Collaborative Group. Study outcomes This protocol will specify the primary outcome for efficacy, as ‘favorable’ outcome defined by the ordinal distribution of the modified Rankin Scale measured at three-months poststroke, but with modified Rankin Scales 5 and 6 collapsed into a single category. The primary analysis will aim to answer the questions: ‘what is the treatment effect of endovascular therapy with intravenous recombinant tissue plasminogen activator compared to intravenous tissue plasmi-nogen activator alone on full scale modified Rankin Scale at 3 months?’ and ‘to what extent do key patient characteristics influence the treatment effect of endovascular therapy?’. Key secondary outcomes include effect of endovascular therapy on death within 90 days; analyses of modified Rankin Scale using dichotomized methods; and effects of endovascular therapy on symptomatic intracranial hemorrhage. Several secondary analyses will be considered as well as expanding patient cohorts to intravenous recombinant tissue plasminogen activator-ineligible patients, should data allow. Discussion This collaborative meta-analysis of individual participant data from randomized trials of endovascular therapy vs. control in conjunction with intravenous thrombolysis will demonstrate the efficacy and generalizability of endovascular therapy with intravenous thrombolysis as a concomitant medication.

Risk factors and outcome of Stroke in renal transplant recipients

Stroke incidence is high in end‐stage renal disease, and risk factors differ between the dialysis and general populations. However, risk factors and outcomes following renal transplantation remain unclear. We analyzed all adult patients with a functioning renal transplant from 01/01/2007 to 12/31/2012. Data were extracted from the electronic patient record. Variables associated with stroke were identified by survival analyses; demographic, clinical, and imaging and laboratory variables were assessed and case fatality determined. Follow‐up was until 05/12/2013. A total of 956 patients were identified (median age 40.1 years, 59.9% male). Atrial fibrillation (AF) prevalence was 9.2%, and 38.2% received a transplant during follow‐up. A total of 26 (2.7%) experienced a stroke during 4409 patient‐years of follow‐up (84.6% ischemic). Stroke incidence was 5.96/1000 patient‐years. Factors associated with stroke on regression analysis were prior stroke, diabetes, age, systolic hypertension, and hemoglobin. Atrial fibrillation was associated with time to stroke (P<0.001). Warfarin did not associate with ischemic stroke risk in those with AF. Fatality was 19.2% at 7, 23.1% at 28, and 42.3% at 365 days after stroke. Patients with a functioning renal transplant have a high stroke incidence and case fatality. Unlike those on hemodialysis, risk factors are similar to the general population. We did not demonstrate benefit from warfarin use in those with AF.

Sex and Stroke in Thrombolyzed Patients and Controls

Background and Purpose— We hypothesized that any sex-related difference in outcome poststroke is explained by other prognostic factors and that the response to intravenous recombinant tissue-type plasminogen activator (r-tPA) is equal in males and females after adjustment for such factors. Methods— We accessed an independent collection of randomized clinical trials—the VISTA (Virtual International Stroke Trials Archive). Data were preprocessed by selecting complete cases (n=8028) and matching females to males (coarsened exact matching, n=4575, 24.3% r-tPA). Outcome was assessed by the 7-point modified Rankin Scale (mRS) measured at 90 days after ischemic stroke. Relationship among variables was estimated by adjusted regression analysis. Results— In nonthrombolyzed patients, ordinal analysis of mRS adjusting for stroke- and sex-related prognostic factors suggested comparable outcomes for females and males (odds ratio, 0.96; 95% confidence interval, 0.85–1.06). Females responded comparably to r-tPA as did males, irrespective of the outcome definition of mRS (ordinal: PInteraction=0.46, relative excess risk because of interaction=0). The number needed to treat was 6.8 and 11.2 for 1 female to achieve mRS score of 0 to 2 and 0 to 1, which was highly congruent with males. Analysis for a nonlinear variation of age-by-sex revealed a good outcome for females <45 years with significant disadvantage thereafter (mRS score of 0–2: PInteraction=0.004). No relationship between sex, r-tPA, and bleeding complications was evident. Conclusions— Functional outcome (mRS) without r-tPA was overall similar between the sexes, as was the response to r-tPA. Nonlinear sex-by-age interaction improved estimates of functional independence; this should be considered in sex-related studies in stroke.

Coagulation and Fibrinolytic Activity of Tenecteplase and Alteplase in Acute Ischemic Stroke

Background and Purpose— We compared the fibrinolytic activity of tenecteplase and alteplase in patients with acute ischemic stroke, and explored the association between hypofibrinogenaemia and intracerebral hemorrhage. Methods— Venous blood samples from a subgroup of participants in the Alteplase–Tenecteplase Trial Evaluation for Stroke Thrombolysis (ATTEST) study were obtained at pretreatment, 3 to 12 hours, and 24±3 hours post-intravenous thrombolysis for analyses of plasminogen, plasminogen activator inhibitor-1, D-dimer, factor V, fibrinogen, and fibrin(ogen) degradation products, in addition to routine coagulation assays. Related sample Wilcoxon signed-rank tests were used to test the within-group changes, and independent Mann–Whitney tests for between-group differences. Results— Thirty patients were included (alteplase=14 and tenecteplase=16) with similar baseline demographics. Compared with baseline, alteplase caused significant hypofibrinogenaemia (P=0.002), prolonged prothrombin time (P=0.011), hypoplasminogenaemia (P=0.001), and lower factor V (P=0.002) at 3 to 12 hours after administration with persistent hypofibrinogenaemia at 24 hours (P=0.011), whereas only minor hypoplasminogenaemia (P=0.029) was seen in the tenecteplase group. Tenecteplase consumed less plasminogen (P<0.001) and fibrinogen (P=0.002) compared with alteplase. Conclusions— In patients with acute ischemic stroke, alteplase 0.9 mg/kg caused significant disruption of the fibrinolytic system, whereas tenecteplase 0.25 mg/kg did not, consistent with the trend toward lower intracerebral hemorrhage incidence with tenecteplase in the ATTEST study. Clinical Trial Registration— URL: http://www.clinicaltrials.gov. Unique identifier: NCT01472926.