Transient ischemic attack (TIA)

MRI
MRI is essential even in those with very low risk TIAs. In one prospective cohort of 1,028 patients with low risk TIA or minor stroke (focal, mild, nonmotor, nonspeech symptoms or less than five minutes of motor or speech symptoms), 13.5% of patients had an ischemic stroke confirmed on MRI. Features suggestive of a likely true ischemic stroke included advancing age, male sex, any motor or speech symptoms, ongoing symptoms, abnormal neurological exam findings, and absence of a prior identical event.

Dual antiplatelet therapy (DAPT)
In patients with minor stroke (NIHSS ≤3 or high-risk TIA (ABCD2 score ≥4), dual antiplatelet therapy for 21 days is likely of benefit. Although dosing regimens varied in the two trials, a reasonable approach is clopidogrel 300 mg PO load, then 75 mg daily, combined with aspirin 81 mg daily for 21 days. After 21 days, single antiplatelet therapy should be continued.  For those with NIHSS ≤5 or high-risk TIA (ABCD2 score ≥6, dual antiplatelet therapy with ticagreol 180 mg load and then 90 mg twice daily, combined with aspirin 81 mg daily for 30 days, is another option.

Clopidogrel in High-Risk Patients with Acute Nondisabling Cerebrovascular Events (CHANCE) trial (2013)
This trial randomized 5,170 patients with minor stroke or high-risk TIA to 21 days of DAPT (clopidogrel + aspirin) vs. aspirin alone. They showed a lower incidence of stroke in the DAPT group (HR 0.68, 95% CI 0.57-0.81), with similar rates of hemorrhage. However, this study was done in an Asian population, so its conclusions for all patients were limited.

Platelet-Oriented Inhibition in New TIA and Minor Ischemic Stroke (POINT) trial (2018)
This multicenter/multicontinent trial randomized 4,881 patients with minor stroke or high-risk TIA to 90 days of DAPT (clopidogrel + aspirin) vs. aspirin alone. They showed a lower incidence of ischemic stroke of 4.6% vs 6.3% (HR 0.72, 95% CI 0.56-0.92) with a higher incidence of major hemorrhage (0.9% vs 0.4%, HR 2.32, 95% CI 1.10-4.87) which was predominantly extracranial hemorrhage. The incidence of intracranial hemorrhage was not statistically different between the two groups.

Meta-analysis of CHANCE and POINT (2019)
In a combined meta-analysis of CHANCE and POINT, DAPT with clopidogrel and aspirin reduced the incidence of major ischemic events (ischemic stroke, MI, or death from ischemic causes) at 90 days in the 0-21 day period (5.2% vs 7.8%, aHR 0.66, 95% CI 0.56-0.77) but not in the 22-90 day period. There was no significant difference in major hemorrhage.

Acute Stroke or Transient Ischemic Attack Treated with Ticagrelor and ASA for Prevention of Stroke and Death (THALES, 2020)
This trial randomized 11,016 patients with noncardioembolic ischemic stroke of mild-moderate ischemic stroke (NIHSS 5 or less), or a high-risk TIA to either 30 days of ticagrelor 180 mg once and then 90 mg twice daily plus aspirin (300-325 mg the first day then then 75-100 mg thereafter), or matching placebo plus aspirin. The primary outcome of stroke or death occurred less frequently in the ticagrelor-aspirin group (5.5% vs 6.6%, HR 0.83, 95% CI 0.71-0.96, p-0.02). This was primarily driven by a reduction in ischemic stroke, as the death rate was similar in both groups. There was more intracranial hemorrhage or severe bleeding in the ticagrelor-aspirin group (0.4% vs 0.1%, HR 3.66, 95% CI 1.48-9.02, p=0.005).

Disparities
Black race is associated with a higher risk of ischemic stroke after TIA (HR 1.6, 95% CI 1.1-2.3).