Thrombectomy for Tandem Occlusions: The Case for Emergent Carotid Stenting

Tandem lesions—defined as extracranial internal carotid artery (ICA) stenosis or occlusion combined with an intracranial large vessel occlusion—represent approximately 15–20% of anterior circulation strokes undergoing thrombectomy. These cases pose unique challenges: two lesions requiring treatment, decisions about timing and sequence of intervention, and concerns about antiplatelet management in the setting of thrombolysis. Unlike the neutral results seen in distal occlusion trials, the evidence for tandem lesions consistently supports acute intervention on the cervical carotid during thrombectomy.

The Challenge of Tandem Lesions

Tandem occlusions present several management dilemmas that distinguish them from isolated intracranial LVO:

• Access: The cervical ICA lesion may impede catheter navigation to the intracranial occlusion
• Two targets: Both the extracranial stenosis and intracranial clot require treatment consideration
• Antiplatelet timing: Carotid stenting typically requires dual antiplatelet therapy, raising bleeding concerns in patients who received IV thrombolysis
• Sequence: Should operators treat the intracranial occlusion first (to restore brain perfusion quickly) or the extracranial lesion first (to secure access)?

Historically, there was significant equipoise regarding whether to stent the carotid acutely versus defer treatment. Concerns centered on hemorrhagic complications when combining stenting, antiplatelet agents, and thrombolysis. The accumulating registry data has now largely resolved this uncertainty.

The Evidence for Emergent Carotid Stenting

STRATIS Tandem Lesion (2019)

STRATIS was a prospective, multicenter registry of patients undergoing thrombectomy with the Solitaire device. Among 147 patients with tandem lesions, management of the cervical ICA was at physician discretion.

• mRS 0–2 at 90 days: 68.5% (stenting) vs. 42.2% (no stenting); P=0.003
• Symptomatic ICH: 2.9% vs. 0% (not significant)
• Mortality: 12.3% vs. 10.9% (no difference)
• Adjusted OR for good outcome with stenting: 2.41 (95% CI 1.09–5.32; P=0.029)

Clinical Pearl: STRATIS was the first major registry to demonstrate that acute carotid stenting during thrombectomy was associated with better outcomes without increased hemorrhagic risk, even in patients who received IV tPA.

GSR Tandem Lesions (2021)

The German Stroke Registry (GSR) analyzed 874 patients with tandem lesions from 25 centers, comparing acute ICA treatment versus no treatment, and intracranial-first versus extracranial-first approaches.

• mRS 0–2 at 90 days: 39.5% (ICA treatment) vs. 29.3% (no treatment); P<0.001
• Mortality: 17.1% vs. 27.1%; P<0.001
• Successful reperfusion (TICI 2b–3): 88.3% vs. 62.8%; P<0.001
• Time to reperfusion: Intracranial-first was faster (53.5 vs. 72.0 min; P<0.001)
• IV thrombolysis improved odds of reperfusion (OR 10.6; P=0.033)

Clinical Pearl: GSR provided key insights on procedural strategy—the intracranial-first approach achieved faster reperfusion, and IV thrombolysis enhanced rather than hindered recanalization success.

IRIS (2025)

IRIS was an individual patient data meta-analysis of 329 patients with tandem lesions pooled from 6 randomized controlled trials comparing IVT+EVT versus EVT alone.

• 90-day mRS shift: Favored acute stenting (adjusted cOR 1.60; 95% CI 1.03–2.47; P=0.04)
• mRS 0–1 at 90 days: 38% (stenting) vs. 22% (no stenting); adjusted OR 1.91; P=0.03
• No significant difference in sICH or mortality
• Treatment effect not modified by prior IVT (P interaction=0.81)

Clinical Pearl: IRIS provided the highest quality evidence to date by pooling RCT data. The analysis confirmed that prior IV thrombolysis does not increase bleeding risk with emergent stenting and should not deter acute carotid intervention.

SECURIS (2025)

SECURIS was a population-based registry of 578 patients with tandem lesions (≥50% cervical ICA stenosis + intracranial LVO), evaluating both 90-day and 1-year outcomes.

• 90-day mRS shift: Favored eCAS (cOR 1.47; P<0.001)
• 1-year mRS shift: Sustained benefit (cOR 1.47; P=0.001)
• Successful recanalization: 91.7% (eCAS) vs. 73.0% (no eCAS); P<0.001
• Hemorrhagic transformation: 16.9% vs. 12.5% (not significant)
• Benefit consistent in moderate (50–69%) and severe (≥70%) stenosis

Clinical Pearl: SECURIS demonstrated that the benefit of emergent stenting persists at 1-year follow-up, and that even moderate ICA stenosis (50–69%) warrants acute treatment.

CERES-TANDEM (2026)

CERES-TANDEM is the largest study to date, analyzing 4,053 patients with anterior circulation tandem lesions undergoing EVT.

• 90-day mRS shift: Favored eCAS (cOR 1.31; 95% CI 1.17–1.47; P<0.001)
• mRS 0–1 at 90 days: 29.1% (eCAS) vs. 20.2% (no eCAS)
• Successful recanalization: 3-fold higher with eCAS (OR 3.09; P<0.001)
• No significant increase in symptomatic ICH
• Effect consistent across access route, IVT use, sedation type, and occlusion site

Clinical Pearl: CERES-TANDEM confirmed the benefit of eCAS in a massive cohort, with consistent results across multiple subgroups. The 3-fold improvement in recanalization rates underscores why acute carotid treatment improves outcomes—it facilitates successful intracranial reperfusion.

Procedural Considerations

Approach Sequence

Two strategies exist for tandem lesions:

• Intracranial-first: Cross the cervical lesion, perform intracranial thrombectomy, then return to stent the carotid. GSR data suggests this achieves faster reperfusion.
• Extracranial-first: Stent the carotid first to secure access, then proceed with intracranial thrombectomy. May be preferred when the cervical lesion prevents catheter passage.

Antiplatelet Management

Carotid stenting typically requires antiplatelet therapy. Common approaches include:

• IV aspirin and/or cangrelor during the procedure
• Deferred oral loading until post-procedure imaging confirms no hemorrhage
• The IRIS meta-analysis found no interaction between IVT and stenting outcomes, suggesting antiplatelet concerns may be overstated

Technical Factors

Successful tandem intervention requires attention to:

• Adequate guide catheter support
• Embolic protection device use (when feasible)
• Stent sizing appropriate for the cervical ICA
• Post-stent angioplasty if needed for residual stenosis

Remaining Questions

Despite the consistent registry data, important questions remain:

• No dedicated RCT: While IRIS pooled RCT data, no trial has randomized patients specifically based on tandem lesion management
• Optimal antiplatelet regimen: Timing, agent selection, and duration remain variable across centers
• Posterior circulation: Data on vertebral artery tandem lesions is limited
• Long-term outcomes: Stent patency, restenosis rates, and need for reintervention require further study

Conclusion

The evidence for emergent carotid stenting in tandem occlusions stands in striking contrast to the neutral MeVO trials. Across five major studies—STRATIS, GSR, IRIS, SECURIS, and CERES-TANDEM—acute carotid intervention consistently improves both recanalization rates and functional outcomes without significantly increasing hemorrhagic complications. Current evidence supports eCAS as the preferred approach for most patients with tandem lesions undergoing thrombectomy.