Tapan Mehta, MBBS, MPH
Clots retrieved from mechanical thrombectomy have been analyzed/studied in the past decade by multiple investigators, and the interest is growing with improved clot retrieval devices. Choi et al. investigate response of intravenous thrombolytics on mechanically retrieved clots in a single-center retrospective study that was conducted over 2 years.
Patients with large vessel anterior circulation strokes receiving tPA within 4.5 hours with baseline mRS <= 2, NIHSS >=4, and ASPECT>=6 were included in the study. Patients also receive baseline MRI before the procedure specifically to evaluate clot burden and nature using the Gradient Echo sequence. The response to intravenous thrombolytic was determined using the Clot Burden Score comparing baseline CTA to conventional angiogram pre thrombectomy images. Additional assessment of intravenous thrombolytic effectiveness was also assessed using the Qureshi scale. Mechanical thrombectomies were performed using Solitaire and Trevo stent retriever device or Penumbra suction catheter. The thrombectomy approaches were not universal; the authors mention use of angioplasty and tirofiban infusion in cases with initial failed attempts. The clots (including all pieces) retrieved from thrombectomy were fixed in 10% neutral buffered formalin. Subsequently, paraffin wax embedded tissues were cut into 4-micro meter sections and stained with hematoxylin-eosin and Martius scarlet blue staining. The sections were digitally scanned and analyzed by blinded examiners. Subgroups based on RBC content with the lowest, middle and highest tertiles and Intravenous thrombolytic responsiveness were further examined.