Thrombectomy for Stroke in the Public Health Care System of Brazil

BACKGROUND

Randomized trials involving patients with stroke have established that outcomes are improved with the use of thrombectomy for large-vessel occlusion. These trials were performed in high-resource countries and have had limited effects on medical practice in low- and middle-income countries.

METHODS

We studied the safety and efficacy of thrombectomy in the public health system of Brazil. In 12 public hospitals, patients with a proximal intracranial occlusion in the anterior circulation that could be treated within 8 hours after the onset of stroke symptoms were randomly assigned in a 1:1 ratio to receive standard care plus mechanical thrombectomy (thrombectomy group) or standard care alone (control group). The primary outcome was the score on the modified Rankin scale (range, 0 [no symptoms] to 6 [death]) at 90 days.

RESULTS

A total of 300 patients were enrolled, including 79 who had undergone thrombectomy during an open-label roll-in period. Approximately 70% in the two groups received intravenous alteplase. The trial was stopped early because of efficacy when 221 of a planned 690 patients had undergone randomization (111 to the thrombectomy group and 110 to the control group). The common odds ratio for a better distribution of scores on the modified Rankin scale at 90 days was 2.28 (95% confidence interval [CI], 1.41 to 3.69; P = 0.001), favoring thrombectomy. The percentage of patients with a score on the modified Rankin scale of 0 to 2, signifying an absence of or minor neurologic deficit, was 35.1% in the thrombectomy group and 20.0% in the control group (difference, 15.1 percentage points; 95% CI, 2.6 to 27.6). Asymptomatic intracranial hemorrhage occurred in 51.4% of the patients in the thrombectomy group and 24.5% of those in the control group; symptomatic intracranial hemorrhage occurred in 4.5% of the patients in each group.

CONCLUSIONS

In this randomized trial conducted in the public health care system of Brazil, endovascular treatment within 8 hours after the onset of stroke symptoms in conjunction with standard care resulted in better functional outcomes at 90 days than standard care alone. (Funded by the Brazilian Ministry of Health; RESILIENT ClinicalTrials.gov number, NCT02216643.).

Abstract TP4: Age is an Important Effect Modifier of Mechanical Thrombectomy: A Subgroup Analysis of the Resilient Trial

Background: Randomized trials performed in high income countries have shown similar effects of mechanical thrombectomy (MT) in elderly and non-elderly patients with large vessel ischemic strokes (LVO). We aimed to assess the effect of age on the clinical outcome of MT in RESILIENT (a randomized, prospective, multicenter, controlled, phase III, clinical trial with blinded outcome assessment performed in Brazil designed to assess the safety, efficacy, and cost-effectiveness of mechanical thrombectomy as compared to medical treatment alone).

Methods: Patients were classified as elderly and non-elderly (≤ 70 vs. > 70 years). The end-points were the common odds ratio (cOR) of mRs (shift analysis) and the frequency of functional independence (mRS 0-2) at 90 days. Ordinal logistic regression analysis (unadjusted and adjusted for important potential confounders) with age group as an interaction term were performed. A p value < 0.05 was considered statistically significant.

Results: Among 221 randomized patients (117- 52.9% males), 89 (40.2%) were classified as elderly. Age had an important effect modification of MT on the mRS shift analysis (elderly - cOR 1.20 95% CI [0.57-2.51] vs. non-elderly cOR 3.9, 95% CI [1.65-5.80], p-interaction = 0.003) and on the frequency of functional independence at 90 days (elderly - OR 0.92 95% CI [0.33 - 2.59] vs. non-elderly OR 3.56, 95% CI [1.64 - 7.75], p-interaction = 0.04). A similar effect modification was observed after adjusting for IV rt-PA, occlusion site, baseline NIHSS and ASPECTS on the mRS shift analysis (elderly - cOR 1.34, 95% CI [0.63 - 2.86] vs. non-elderly cOR 3.26, 95% CI [1.73 - 6.13], p-interaction = 0.06) and on the frequency of functional independence at 90 days (elderly - OR 1.08 95% CI [0.36 - 3.21] vs. non-elderly OR 4.26, 95% CI [1.85 - 9.82], p-interaction = 0.04) .

Conclusion: The large effect size of MT on LVO outcomes is significantly diminished in the elderly population of patients treated under the less than ideal conditions typically found in the public healthcare system of a developing country.

Abstract TP17: The Smoking-Thrombolysis Paradox: a Matched Case-Control Study

Background and Purpose: Smoking is a well-established risk factor for stroke. However, several studies have shown that smokers with stroke have better outcomes after thrombolysis, a phenomenon commonly known as the smoking-thrombolysis paradox. We investigated whether clinical and procedural outcomes differ between smokers and non-smokers with large vessel occlusion stroke after endovascular therapy.

Methods: We reviewed our prospectively collected endovascular database at a tertiary care academic institution between Sep 2010-Dec 2016. All patients that underwent endovascular therapy for anterior circulation large vessel occlusion acute ischemic stroke were included and categorized into two groups: (1) current smokers and (2) non-smokers. The 2 groups were then matched for age, baseline NIHSS and glucose levels using a weighted Euclidian distance method. Baseline, procedural, and radiological characteristics, as well as outcome parameters were compared.

Results: A total of 326 (163 matched pairs) qualified for the study. Smokers had higher rates of dyslipidemia (48.5% vs 28.8%, p<0.001), lower body mass index (26.7[23.5-31.3] vs 28.4[24.9-32.6], p=0.03) and shorter procedures (63[45-82] vs 73.5[46-116], p=0.03). Other baseline characteristics including baseline NIHSS, ASPECT scores, CT Perfusion parameters (ischemic core and penumbra volumes) and median time to treatment were well balanced. When compared with non-smokers, smokers also had similar rates of good outcomes at 90 days (mRS 0-2) (58.2% vs 52.4%, p=0.33), successful reperfusion (mTICI 2b-3) (92% vs 89.6%, p=0.44), parenchymal hematomas (7.4% vs 6.7%, p=0.83) and mortality at 90 days (14.9% vs 15.6%, p=0.86). On multivariate analysis, age (OR 0.97 95%CI [0.94-0.99], p=0.006), pretreatment glucose (OR 0.99 95%CI [0.98-0.99], p=0.02), baseline NIHSS (OR 0.92 95%CI [0.87-0.97], p=0.002) and successful reperfusion (OR 6.98 95%CI [2.19-22.25] were associated with good outcome.

Conclusion: Our data shows that smoking is not associated with outcomes in patients with large vessel occlusion stroke treated with mechanical thrombectomy.

Abstract WP43: Body Mass Index and Clinical Outcomes in Large Vessel Occlusion Acute Ischemic Stroke After Endovascular Therapy: The Obesity Paradox

Background: Obesity has been associated with increased morbidity and mortality in the general population. However, several reports have described lower mortality rates in overweight or obese patients as compared to normal weight ones. Several studies have investigated the phenomenon, commonly known as the obesity paradox, with mixed results thus far. We sought to determine whether clinical outcomes differ between patients with acute ischemic stroke after endovascular therapy according to their body mass index (BMI).

Methods: We reviewed our prospectively collected endovascular database at a tertiary care academic institution. All patients that underwent endovascular therapy for acute large vessel occlusion acute ischemic stroke were categorized according to their BMI into four groups (1) underweight (BMI<18.5), (2) normal weight (BMI=18.5-25), (3) overweight (BMI=25-30) and (4) obese (BMI>30). Baseline characteristics, procedural radiological as well as outcome parameters were compared.

Results: A total of 926 patients qualified for the study of which 20 (2.2%) were underweight, 253 (27.3%) had a normal weight, 315 (34%) were overweight and 338 (36.5%) obese. When compared with normal weight (reference) overweight patients had higher rates of dyslipidemia as well as diabetes and higher glucose and HbA1c levels while obese patients were younger, less often smokers and had higher rates of hypertension as well as diabetes and higher glucose and HbA1c levels. Other baselines characteristics including NIHSS and ASPECT scores as procedural characteristics were comparable between groups. In terms of outcomes, rates of successful reperfusion (mTICI 2b-3), parenchymal hematomas, 90-Day good clinical outcomes (modified Rankin scale, mRS 0-2) and 90-day mortality were comparable between BMI groups. On multivariate analysis, BMI was not associated with good outcomes nor mortality whether as a continuous variables or a categorical variable comparing groups with normal weight patients (reference) two by two.

Conclusions: In stroke patients treated with mechanical thrombectomy, BMI does not seem to be associated with outcomes. However, patients who are overweight or obese have more co-morbities and should strive for a normal weight.

Selection Paradigms for Large Vessel Occlusion Acute Ischemic Stroke Endovascular Therapy

Background: Optimal patient selection methods for thrombectomy in large vessel occlusion stroke (LVOS) are yet to be established. We sought to evaluate the ability of different selection paradigms to predict favorable outcomes. Methods: Review of a prospectively collected database of endovascular patients with anterior circulation LVOS, adequate CT perfusion (CTP), National Institutes of Health Stroke Scale (NIHSS) ≥10 from September 2010 to March 2016. Patients were retrospectively assessed for thrombectomy eligibility by 4 mismatch criteria: Perfusion-Imaging Mismatch (PIM): between CTP-derived perfusion defect and ischemic core volumes; Clinical-Core Mismatch (CCM): between age-adjusted NIHSS and CTP core; Clinical-ASPECTS Mismatch (CAM-1): between age-adjusted NIHSS and ASPECTS; Clinical-ASPECTS Mismatch (CAM-2): between NIHSS and ASPECTS. Outcome measures were inclusion rates for each paradigm and their ability to predict good outcomes (90-day modified Rankin Scale 0-2). Results: Three hundred eighty-four patients qualified. CAM-2 and CCM had higher inclusion (89.3 and 82.3%) vs. CAM-1 (67.7%) and PIM (63.3%). Proportions of selected patients were statistically different except for PIM and CAM-1 (p = 0.19), with PIM having the highest disagreement. There were no differences in good outcome rates between PIM(+)/PIM(-) (52.2 vs. 48.5%; p = 0.51) and CAM-2(+)/CAM-2(-) (52.4 vs. 38.5%; p = 0.12). CCM(+) and CAM-1(+) had higher rates compared to nonselected counterparts (53.4 vs. 38.7%, p = 0.03; 56.6 vs. 38.6%; p = 0.002). The abilities of PIM, CCM, CAM-1, and CAM-2 to predict outcomes were similar according to the c-statistic, Akaike and Bayesian information criterion. Conclusions: For patients with NIHSS ≥10, PIM appears to disqualify more patients without improving outcomes. CCM may improve selection, combining a high inclusion rate with optimal outcome discrimination across (+) and (-) patients. Future studies are warranted.

Even Small Decreases in Blood Pressure during Conscious Sedation Affect Clinical Outcome after Stroke Thrombectomy: An Analysis of Hemodynamic Thresholds

BACKGROUND AND PURPOSE

The adverse effects of general anesthesia in stroke thrombectomy have been attributed to intraprocedural hypotension, yet optimal hemodynamic targets remain elusive. Identifying hemodynamic thresholds from patients without exposure to general anesthesia may help separate the effect of hypotension from the effect of anesthesia in thrombectomy outcomes. Therefore, we investigated which hemodynamic parameters and targets best correlate with outcome in patients treated under sedation with monitored anesthesia care.

MATERIALS AND METHODS

We performed a retrospective analysis of a prospectively collected data base of patients with anterior circulation stroke who were successfully reperfused (modified TICI ≥ 2b) under monitored anesthesia care sedation from 2010 to 2015. Receiver operating characteristic curves were generated for the lowest mean arterial pressure before reperfusion, both as absolute values and relative changes from baseline. Cutoffs were tested in binary logistic regression models of poor outcome (90-day mRS > 2).

RESULTS

Two-hundred fifty-six of 714 patients met the inclusion criteria. In a multivariable model, a ≥10% mean arterial pressure decrease from baseline had an OR for poor outcome of 4.38 (95% CI, 1.53-12.56; P < .01). Other models revealed that any mean pressure of <85 mm Hg before reperfusion had an OR for poor outcome of 2.22 (95% CI, 1.09-4.55; P = .03) and that every 10-mm Hg drop in mean arterial pressure below 100 mm Hg had an OR of 1.28 (95% CI, 1.01-1.62; P = .04).

CONCLUSIONS

A ≥10% mean arterial pressure drop from baseline is a strong risk factor for poor outcome in a homogeneous population of patients with stroke undergoing thrombectomy under sedation. This threshold could guide hemodynamic management of patients during sedation and general anesthesia.

Early Endovascular Treatment in Intravenous Tissue Plasminogen Activator–Ineligible Patients

Background and Purpose—

Intravenous tissue-type plasminogen activator (tPA) treatment in acute stroke has many exclusion criteria. We aimed to assess the safety and efficacy of endovascular therapy (ET) in intravenous (IV) tPA-ineligible patients.

Methods—

Retrospective analysis of a prospectively collected database of consecutive patients treated with ET within 6 hours of stroke onset between September 2010 and April 2015. Patients treated with IV-tPA followed by ET were compared with those treated with ET alone because of IV-tPA ineligibility. Efficacy and safety end points included the rates of good outcome (90-day modified Rankin scale score ≤2), successful reperfusion (modified Treatment in Cerebral Ischemia 2b-3), parenchymal hematoma (PH-1 and PH-2), and 90-day mortality. Univariate and logistic regression were performed to identify the predictors of outcomes.

Results—

A total of 422 patients were included. Two hundred and fifty-three (59%) patients received IV-tPA+ET, and 169 (41%), ET alone. Combined IV-tPA+ET patients were slightly younger (64.9±15.2 versus 67.9±14.9 years; P =0.05), more often males (56% versus 44%; P =0.01), and had less hypertension (70% versus 81%; P =0.02) and vertebrobasilar occlusions (3% versus 8%; P =0.02). The remaining baseline characteristics, including National Institutes of Health Stroke Scale score (20 [15–23] versus 19 [15–24]; P =0.85), Alberta Stroke Program Early CT Score (ASPECTS; 8 [7–9] versus 8 [7–9]; P =0.24), and stroke onset to puncture times (235±70 versus 240±81 minutes; P =0.27), were similar across both groups. There were no significant differences in the rates of modified Treatment in Cerebral Ischemia 2b-3 (83% versus 80%; P =0.52), 90-day modified Rankin scale score ≤2 (45% versus 38%; P =0.21), or any PH (3% versus 5%; P =0.21). Unadjusted 90-day mortality was higher with ET alone (21% versus 34%; P <0.01); however, IV-tPA ineligibility was not associated with modified Treatment in Cerebral Ischemia 2b-3, any PH, good outcome, or 90-day mortality on logistic regression.

Conclusions—

IV-tPA-eligible and -ineligible patients seem to have similar outcomes after early ET.

Endovascular Treatment for Acute Ischemic Stroke in the Setting of Anticoagulation

Background and Purpose—

Oral anticoagulation (OAC) plays a major role in atrial fibrillation stroke prevention but represents a contraindication to intravenous tissue-type plasminogen activator. Intra-arterial therapy remains a potential reperfusion strategy in these patients; however, supporting data are scarce.

Methods—

Retrospective analysis of prospectively collected consecutive intra-arterial therapies from October 2010 to March 2015 comparing OAC (vitamin-K antagonists and novel oral anticoagulants) versus normal hemostasis versus intravenous tissue-type plasminogen activator patients. Primary safety end point is parenchymal hematoma. Secondary safety end point is 90-day mortality. Efficacy end points are successful reperfusion (modified Thrombolysis in Cerebral Infarction, 2b-3) and good outcome (90-day modified Rankin Scale score of 0–2). Logistic regression for predictors of parenchymal hematoma was performed.

Results—

A total of 604 patients were qualified for the study. Baseline and outcomes variables were overall similar for vitamin-K antagonists (n=29) and novel oral anticoagulants (n=17) patients. When compared with normal hemostasis (n=265) and intravenous tissue-type plasminogen activator (n=297), OAC (n=46) patients were older and had more comorbidities. There were no statistically significant differences in the rates of parenchymal hematoma (8% versus 5%; P =0.42), 90-day modified Rankin Scale score of 0 to 2 (30% versus 40%; P =0.26), and 90-day mortality (32% versus 26%; P =0.46) among OAC and normal hemostasis patients. Similarly, there were no significant differences between OAC and intravenous tissue-type plasminogen activator patients in terms of parenchymal hematoma (8% versus 4%; P =0.16), 90-day modified Rankin Scale score of 0 to 2 (30% versus 43%; P =0.13), and 90-day mortality (32% versus 22%; P =0.18). The use of OAC was not associated with the occurrence of parenchymal hematoma on multivariate logistic regression analysis.

Conclusions—

Intra-arterial therapy seems to be safe in patients taking OACs; however, our study showed a nonsignificant increase in hemorrhage and mortality with a nonsignificant decrease in good outcomes in comparison with non-OAC patients. Although these nominal differences may have been related to older age and more comorbidities in the OAC group, larger studies are needed to confirm our findings given our limited sample size.