Detection of Microvascular Failure After Thrombectomy Directly in the Angio-Suite Using Parametric Color Coding.

Purpose: The "no-reflow phenomenon" refers to persisting microvascular failure despite complete macrovascular reperfusion. We investigated whether parametric color coding (PCC) analysis of the DSA-series after successful mechanical thrombectomy could predict microvascular dysfunction.

Methods: We retrospectively analyzed the STAMINA database for patients admitted to a single tertiary care center over a 5-year period with MCA-Occlusion (M1 or M2 branch), large penumbra, TICI 3 and infarct volume exceeding 15 ml on follow-up CT-presumed to reflect microvascular failure. These 55 patients were compared to 55 controls with infarcts < 15 ml on follow-up CT. As proof of concept, we included 42 non-stroke patients undergoing elective treatment of unruptured intracranial aneurysms. Using iFlow-PCC software, we calculated critical flow parameters, including cerebral circulation time (CirT), relative cortical time to peak (rTTP), and microvascular transit time (mTT).

Results: Microvascular transit time (mTT) was significantly prolonged in the suspected microvascular failure group (3.22 ± 0.85 s) compared to the recanalization control group (2.79 ± 0.64 s; p = 0.003) and the non-stroke interventional control group (2.54 ± 0.90 s, p = 0.0003). The group with suspected microvascular failure exhibited a median modified Rankin Score at 3 months (mRS 3M: 4, IQR: 3-5) and a higher number of poor outcomes (mRS 5-6; n = 16) compared to the control group with similar strokes (median mRS 3M: 2, IQR: 1-4; mRS 5-6: n = 4).

Conclusion: Prolonged microvascular transit time (mTT) can predict microvascular failure after thrombectomy. Angiographic flow analysis, performed directly in the angio-suite allows early identification of patients who may benefit from additional therapy like intra-arterial thrombolysis.