Elizabeth M. Aradine, DO
Parenchymal hematoma (PH) is a potential complication of IV thrombolytics or mechanical thrombectomy; however, risk factors for hematoma after thrombectomy are still uncertain. PH after acute stroke intervention can increase morbidity and mortality. In this study, the authors retrospectively reviewed data from a registry of thrombectomy patients to identify variables to predict post thrombectomy PH. Patients presenting with an anterior circulation large vessel or intracranial carotid occlusion who had a thrombectomy from 2011-2016 were included. MRI or CT based brain and vessel imaging were used to select patients for thrombectomy and to calculate the ASPECT score. Post thrombectomy, a 24-hour brain image was routinely performed on all patients to evaluate for PH. PH was classified using the European Cooperative Acute Stroke Study (ECASS) criteria. 90-day post stroke outcome was assessed using the mRS. This data was compared to baseline patient characteristics including age, smoking status, hypertension, diabetes, admission NIHSS, and antiplatelet or anticoagulation use. Data on the presence of collateralization on angiogram and general anesthesia use was also recorded.
1316 patients fit inclusion criteria, and 66.1% received IV thrombolytics before thrombectomy. A TICI score of 2b-3 was achieved in 76.7%. 3.4% of patients had PH type 1 on 24-hour imaging while 8.2% had PH type 2. The presence of PH increased mortality compared to those without PH (37.5% vs 16.7%, P<0.0001) and mRS ≥3 at 90 days was higher in the PH group (28.3% vs 51.0%, P<0.0001). Those with a PH on 24-hour imaging had a higher NIHSS, lower ASPECT score, unfavorable collaterals, required general anesthesia, had intraprocedural embolization of a new vascular territory, were older and smoked at the time of ischemic stroke. Based on the presence of these factors, the authors suggest they may be independent predictors of hematoma post thrombectomy.
The independent factors of high NIHSS, low ASPECT score and unfavorable collaterals are likely interrelated. A low ASPECT score reflects a large infarction which can result in a high NIHSS. A large infarction within 6 hours of symptom onset may indicate poor collateralization. Those presenting with a larger stroke are more likely to be intubated prior to thrombectomy, which was reflected in this study (Table II supplement). General anesthesia is reported as an independent predictor of PH; however, the above factors were not adjusted for, thus risk may not be as high as reported. Furthermore, other factors that can increase bleeding risk, such as liver and renal disease, coagulopathy, malignancy, and atrial fibrillation, were not accounted for. In this study, anticoagulation did not increase PH rates; however, it is unclear if anticoagulation was therapeutic on admission. Although presence of PH showed increased morbidity and mortality, it cannot be determined that PH itself increases morbidity and mortality, as this is influenced by many other factors.
Knowledge of prestroke mRS and cause of death should be considered when evaluating the effect of PH after thrombectomy. Combining interrelated factors such as NIHSS, ASPECT score, and collateralization should be considered when evaluating the incidence of PH post thrombectomy. Adjusting for these factors may show PH independently increases morbidity and mortality, therefore predicting PH would be more influential. Further studies adjusting for variables that increase bleeding risk would expand understanding of post thrombectomy PH risk. If predictive factors are identified, a PH tool can be created to rapidly identify these patients.