Stroke Prevention: Carotid Stenosis Management and Dual Antiplatelet Therapy Evidence

Ticagrelor in Stroke Prevention: THALES Trial

The THALES trial compared aspirin plus ticagrelor (180 mg load, then 90 mg BID for 30 days) versus aspirin alone in minor stroke/TIA. The combination reduced 30-day stroke or death from 6.6% to 5.5% (HR 0.83, 95% CI 0.71-0.96)[6], with an increase in severe bleeding (0.5% vs 0.1%). Ticagrelor-based DAPT may be considered when clopidogrel resistance is suspected (CYP2C19 loss-of-function alleles present in 25-30% of populations) or when rapid onset of antiplatelet effect is needed, given ticagrelor's faster pharmacodynamic profile compared to clopidogrel.

Long-Term Secondary Prevention

After the initial 21-30 day DAPT window, long-term secondary prevention consists of single antiplatelet therapy (aspirin 81 mg or clopidogrel 75 mg), high-intensity statin (targeting LDL <70 mg/dL, with the TST trial showing benefit from targeting LDL <70 vs 90-110 mg/dL[10]), and blood pressure control (<130/80 mmHg per SPRINT data extrapolation, with the SPS3 trial supporting <130 systolic in lacunar stroke[11]). For patients with embolic stroke of undetermined source (ESUS), the NAVIGATE ESUS and RE-SPECT ESUS trials showed no benefit of rivaroxaban or dabigatran over aspirin[8][9], maintaining aspirin as the default antiplatelet for non-cardioembolic stroke. For patients with concurrent peripheral artery disease, antiplatelet selection may differ. AF screening with prolonged cardiac monitoring (30-day event recorder or implantable loop recorder) is recommended in cryptogenic stroke, with the CRYSTAL-AF trial showing AF detection in 30% with implantable monitoring at 3 years[7].

Putting It Together: Time-Sensitive Decisions

Stroke prevention is fundamentally time-sensitive at every stage. In the acute phase after minor stroke or TIA, initiating DAPT within 12-24 hours captures the period of highest recurrence risk. For symptomatic carotid stenosis, revascularization within 14 days of the index event provides the greatest benefit — the protective effect of CEA diminishes substantially when performed weeks or months later. And in long-term secondary prevention, achieving LDL and blood pressure targets rapidly rather than titrating slowly over months reduces the cumulative risk of recurrence. The common thread across all these decisions is urgency: the clinician who acts quickly and decisively in the post-stroke period provides measurably better protection than one who defers decisions to subsequent outpatient visits.

Limitations and Evolving Evidence

The CHANCE trial enrolled exclusively Chinese patients, and whether the magnitude of DAPT benefit generalizes fully to other populations is an open question, though the POINT trial (international cohort) produced directionally consistent results. The optimal management of asymptomatic carotid stenosis awaits the full CREST-2 results — until then, the decision between modern medical therapy alone and revascularization remains a shared decision informed by the patient's stenosis progression, imaging characteristics, and operative risk. And the ESUS trials definitively closed the door on empiric anticoagulation for cryptogenic stroke without documented AF, reinforcing the importance of thorough cardiac monitoring before concluding that anticoagulation is indicated.

References

1. Clinical alert: benefit of carotid endarterectomy for patients with high-grade stenosis of the internal carotid artery (NASCET)
2. Stenting versus endarterectomy for treatment of carotid-artery stenosis (CREST)
3. Stenting versus endarterectomy for treatment of carotid-artery stenosis (CREST)
4. Clopidogrel with aspirin in acute minor stroke or transient ischemic attack (CHANCE)
5. Clopidogrel and Aspirin in Acute Ischemic Stroke and High-Risk TIA (POINT)
6. Ticagrelor and Aspirin or Aspirin Alone in Acute Ischemic Stroke or TIA (THALES)
7. Cryptogenic stroke and underlying atrial fibrillation (CRYSTAL-AF)
8. Rivaroxaban for Stroke Prevention after Embolic Stroke of Undetermined Source (NAVIGATE ESUS)
9. Dabigatran for Prevention of Stroke after Embolic Stroke of Undetermined Source (RE-SPECT ESUS)
10. Benefit of Targeting a LDL Cholesterol <70 mg/dL During 5 Years After Ischemic Stroke (TST)
11. Blood-pressure targets in patients with recent lacunar stroke: the SPS3 randomised trial