The presence of atrial fibrillation (AF) may reduce the likelihood of mechanical thrombectomy being successful at the first attempt in patients with acute ischaemic strokes caused by medium-vessel occlusions (MeVOs). That is according to a registry study published recently in Interventional Neuroradiology by senior author Manisha Koneru (Cooper University Health Care, Camden, USA), lead author Omnea Elgendy (Cooper Medical School of Rowan University, Camden, USA), and colleagues.
“FPE [first-pass effect] is strongly associated with improved clinical outcomes following acute ischaemic stroke for patients treated with EVT [endovascular therapy], correlated with better functional outcomes, less vascular injury, lower risk of clot fragments, and decreased time to reperfusion,” Koneru, Elgendy et al write in their report. “Previous studies have shown an association between AF and achieving FPE during EVT for LVO [large vessel occlusion]—however, this association has yet to be widely investigated for MeVOs. In our study, AF was significantly associated with lower odds of FPE and mFPE [modified FPE] in MeVOs treated with EVT. Clinically, this may suggest a need to prepare for additional passes and intraprocedural rescue strategies to achieve reperfusion in EVT of MeVO patients with AF.”
In an effort to evaluate the relationship between AF and achieving FPE in patients with MeVO stroke, the researchers retrospectively screened a prospectively maintained registry of adult ischaemic stroke patients treated at a comprehensive stroke centre between October 2019 and October 2023. Patients undergoing a thrombectomy for a MeVO were included in the study, with univariable and multivariable logistic regression analyses being performed. The researchers’ primary endpoint was FPE—defined as achieving modified treatment in cerebral infarction (mTICI) 2c–3 after the first thrombectomy pass—and a key secondary outcome of interest was mFPE, defined as achieving mTICI 2b–3 after the first thrombectomy pass. Clinical outcome information collected by the researchers included data on discharge and 90-day modified Rankin scores (mRS).
Koneru, Elgendy et al note that decisions over giving thrombolytic drugs and thrombectomy treatments were made as per multidisciplinary stroke team consensus, while the first-line thrombectomy approach of choice—aspiration only, or aspiration combined with stent-retriever deployment—as well as decisions over devices used intraprocedurally were left to the discretion of each neurointerventionist.
Across 67 patients meeting the study’s inclusion criteria (median age, 70 years; 49.3% female), 23 (34.3%) were found to have AF, and the majority of patients (n=59 [88.1%]) have proximal MeVOs. The researchers also detail that thrombolytics were administered in 23 patients (34.3%) and 41 patients (61.2%) were treated via aspiration-only thrombectomy.
In the study, roughly one third of MeVO patients (34.3%) ultimately achieved FPE. Subsequent multivariable logistic regression analyses revealed that AF was the only assessed factor that impacted FPE rates in a statistically significant way, as per an adjusted odds ratio (aOR) of 0.08 (95% confidence interval [CI], 0.01–0.63]; p=0.02). Age and sex as well as several other variables including hypertension, prior stroke, premorbid mRS, thrombolysis administration and chosen thrombectomy approach were not found to have significantly impacted FPE rates.
More than half of the study population (58.2%) achieved mFPE, Koneru, Elgendy et al report, also noting that multivariable logistic regression analyses showed both AF (aOR, 0.04; 95% CI, 0.01–0.49; p=0.01) and prior antiplatelet/anticoagulant use (aOR, 0.05; 95% CI, 0.01–0.71; p=0.03) to be associated with a statistically significant reduction in mFPE rates.
“Our results contrast with previous studies showing a positive association between AF and achieving FPE during EVT for LVOs,” the authors state. “This suggests that the intraprocedural course in MeVOs may differ from that in LVOs in patients with AF, including aspects such as clot composition, location, and size. Erythrocyte-rich clots are associated with higher rates of successful recanalisation than fibrin-rich clots; however, studies investigating the composition of cardioembolic clots have yielded heterogeneous results.”
Koneru, Elgendy et al go on to note that a recent substudy of the DIRECT-SAFE trial hypothesised that the higher rate of FPE achieved in LVO patients with AF—versus those without AF—could be driven by mature, fibrin-rich cardioembolic clots that are less likely to disintegrate or embolise.
“In contrast, we postulate that these physical properties of cardioembolic thrombi associated with AF may predispose to more difficult thrombectomy courses when targeting MeVOs in comparatively narrower, more distal cerebrovasculature,” they add.
