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

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.

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).

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).

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.