Mechanical thrombectomy outcome
Clinical trials have shown that mechanical thrombectomy (MT) is associated with improved functional outcomes for patients with acute ischemic stroke presenting with proximal anterior circulation, large vessel occlusion, and salvageable brain tissue 1) 2) 3) 4) 5).
Stroke patients who underwent successful thrombectomy with general anesthesia achieved higher rates of functional independence when procedural ETCO2 exceeded 35 mmHg. Further studies to confirm this effect and investigate optimal ETCO2 parameters should be considered 6)
In a cohort study, more than 1 in 5 patients presenting with an ASPECTS of 2 to 5 achieved 90-day functional independence after MT. A favorable outcome was nearly 5 times more likely for patients with low ASPECTS who had successful recanalization. The association of a low ASPECTS with 90-day outcomes did not differ for patients presenting in the early vs extended MT window 7).
For Gariel et al. the primary outcome was favorable 90-day functional outcome defined as a modified Rankin Scale of ≤2. Secondary outcomes were successful reperfusion following all procedures and after the first-line procedure, number of device passes, and change in National Institutes of Health Stroke Scale score at 24 hours 8).
Todo et al. investigated the time-outcome relationships in different age subgroups. Of 2420 patients enrolled in the RESCUE-Japan Registry 2 study, a study based on a prospective registry of stroke patients with acute cerebral large-vessel occlusion at 46 centers, they analyzed the data of 1010 patients with successful reperfusion after endovascular therapy (mTICI of 2b or 3). In 3 age subgroups (< 70, 70 to < 80, and ≥ 80 years), the mRS scores at 90 days were analyzed according to 4 categories of onset-to-reperfusion time (< 180, 180 to < 240, 240 to < 300, and ≥ 300 min). In each age subgroup, the distributions of mRS scores were better with shorter onset-to-reperfusion times. The adjusted common odds ratios for better outcomes per 1-category delay in onset-to-reperfusion time were 0.66 (95% CI 0.55-0.80) in ages < 70 years, 0.66 (95% CI 0.56-0.79) in ages 70 to < 80 years, and 0.83 (95% CI 0.70-0.98) in ages ≥ 80 years. Early reperfusion was associated with better outcomes across all age subgroups. Achieving early successful reperfusion is important even in elderly patients 9).
Mechanical neurothrombectomy achieves a higher likelihood of revascularization than intravenous thrombolysis (IVT), but there remains significant discrepancy between rates of recanalization and rates of favorable outcome. The poor neurological recovery among some stroke patients despite successful recanalization confirms the need for adjuvant therapy, such as pharmacological neuroprotection. Prior clinical trials of neuroprotectant drugs failed perhaps due to inability of the agent to reach the ischemic tissue beyond the occluded artery. A protocol that couples mechanical neurothrombectomy with concurrent delivery of a neuroprotectant overcomes this pitfall. Activated protein C (APC) exerts pleiotropic anti-inflammatory, anti-apoptotic, antithrombotic, cytoprotective, and neuroregenerative effects in stroke and appears a compelling candidate for this novel approach 10).
Embolectomy is the emergency surgical removal of emboli which are blocking blood circulation. It usually involves removal of thrombi (blood clots), and is then referred to as thrombectomy. Embolectomy is an emergency procedure often as the last resort because permanent occlusion of a significant blood flow to an organ leads to necrosis. Other involved therapeutic options are anticoagulation and thrombolysis.
Cervical surgical embolectomy for acute extracranial ICA occlusion resulted in a high complete recanalization rate with an acceptable safety profile. A possible association between severe cardiac illness and huge embolus occluding proximal large artery was suggested 11).
Javed et al. included all eligible adult acute ischemic stroke (AIS) patients treated with endovascular thrombectomy (EVT) at the Montefiore Medical Center from June 2016 to January 2020. Data was systematically collected via chart review including pre-, intra- and post-procedural variables. The outcome was the Modified Rankin Scale (mRS) at 90 days post-EVT where a poor outcome was defined as mRS 3-6: 3-5 for functional dependency and 6 for death. Model selection methods including stepwise and Lasso were evaluated via cross-validation where the final multivariable logistic regression model was chosen by optimizing the Area Under the Receiver Operating Characteristic Curve (ROC AUC).
They included 224 patients (mean age: 65 years old, male: 55%, 90-day poor outcome: 60%). The final model achieved a median AUC of 0.84, IQR: (0.80, 0.87). A 7-point score, called Bronx Endovascular Thrombectomy (BET) score, was developed with more points indicating higher likelihood of 90-day poor outcome (0 point: ≤21% risk; 1-2: 24%; 3: 61%; 4: 86%; 5: 96%; 6-7: ≥99%). One point was awarded for the following variables: current smoker, diabetic, general anesthesia received, puncture to perfusion time ≥45 minutes, and Thrombolysis in Cerebral Infarction (TICI) score <3. Two points were awarded for a post-EVT National Institute of Health Stroke scale (NIHSS) of ≥10.
Incorporating peri-procedural data they developed the competitive BET score predicting 90-day functional dependency and death, which may help providers, patients and caregivers manage expectations and organize early rehabilitative services 12).