Choosing an antithrombotic after ischemic stroke or TIA is one of the highest-yield bedside decisions in vascular neurology, and it is mostly an exercise in classifying mechanism before reaching for a drug. The first fork is whether the event is cardioembolic. If it is — most commonly atrial fibrillation — the answer is anticoagulation. If it is not, the answer is antiplatelet therapy, with a narrow, evidence-defined role for a short course of two agents. This page summarizes how the landmark trials map onto that decision and where reasonable clinicians and institutions still diverge. It is educational and does not replace individualized assessment, current guidelines, or your own institution’s protocols.

Non-cardioembolic stroke: one antiplatelet, long term

For the typical non-cardioembolic ischemic stroke or TIA, long-term secondary prevention rests on a single antiplatelet agent — aspirin 81 mg daily or clopidogrel 75 mg daily are both reasonable first-line choices. There is no convincing evidence that indefinite dual antiplatelet therapy reduces recurrent stroke in the average patient, and continuing two agents long term steadily accrues bleeding risk. The practical question at the bedside is therefore not usually “one drug or two forever,” but rather “does this patient qualify for a short, defined course of two agents up front?”

Short-course DAPT: minor stroke and high-risk TIA

The clearest indication for time-limited dual antiplatelet therapy is the minor non-cardioembolic stroke (NIHSS ≤ 3) or high-risk TIA (ABCD² score ≥ 4). The CHANCE trial in China and the international POINT trial both showed that starting aspirin plus clopidogrel within 24 hours reduced early recurrent ischemic events compared with aspirin alone.12 The benefit is concentrated in the first weeks, which is exactly why the regimen is short: a common practice, supported by these data, is aspirin plus clopidogrel for about 21 days followed by a single agent. POINT used a longer 90-day combination and paid for it with more major hemorrhage, reinforcing that the ischemic benefit is front-loaded while the bleeding risk is not.2

Ticagrelor plus aspirin is an alternative short-course regimen. In THALES, patients with mild-to-moderate non-cardioembolic stroke (NIHSS ≤ 5) or high-risk TIA who received 30 days of ticagrelor plus aspirin had fewer strokes or deaths than those on aspirin alone, again at the cost of more severe bleeding.3 Note the wider NIHSS entry threshold (≤ 5) in THALES than the NIHSS ≤ 3 cut point most often cited for clopidogrel-based DAPT.

Bedside pearl

Write the stop date for the second antiplatelet in your note and in the discharge plan the same day you start it. DAPT that is started for 21 days and never stopped is a preventable source of bleeding; the benefit was earned in the first weeks, not the first year.

Symptomatic intracranial atherosclerotic stenosis

Symptomatic high-grade intracranial atherosclerotic stenosis is its own category. In SAMMPRIS, patients with a recent TIA or stroke attributed to 70–99% stenosis of a major intracranial artery did better with aggressive medical management than with angioplasty and stenting, because the periprocedural stroke risk was high and the medical arm fared better than expected.4 That aggressive medical arm combined 90 days of dual antiplatelet therapy with intensive risk-factor control — tight blood pressure and LDL targets plus lifestyle modification. The lesson for the ward is that the “treatment” here is a package, not a single pill: short-course DAPT plus genuinely aggressive secondary prevention, and a high bar before considering intracranial stenting.

Cardioembolic stroke: anticoagulate, and pick the right agent

When the mechanism is cardioembolic, the decision shifts from platelets to anticoagulation. For most patients with non-valvular atrial fibrillation, a direct oral anticoagulant (DOAC) is preferred over warfarin for comparable or better efficacy with a more favorable intracranial bleeding profile and no INR monitoring. The timing of when to start anticoagulation after an acute infarct is a separate decision driven by infarct size and hemorrhagic transformation risk, and is beyond the scope of this antithrombotic-selection page.

Several settings are exceptions where warfarin remains the agent of choice and DOACs should not be used:

  • Mechanical heart valve — warfarin; DOACs are inferior and contraindicated in this setting.
  • Left ventricular thrombus — warfarin is the better-established choice.
  • Antiphospholipid syndrome — warfarin, particularly in triple-positive patients, where DOACs have performed worse.
  • Moderate-to-severe (rheumatic) mitral stenosis — warfarin; this valvular AF population was excluded from the DOAC trials.

Pitfall

Do not reflexively reach for a DOAC just because the patient has atrial fibrillation. A mechanical valve, an LV thrombus, antiphospholipid syndrome, or rheumatic mitral stenosis all move the choice back to warfarin — substituting a DOAC in these patients can leave them under-protected. Confirm the valve type and the AF substrate before you write the order.

Putting it together

A workable bedside sequence: first decide cardioembolic versus non-cardioembolic. If non-cardioembolic, default to a single antiplatelet long term, and ask whether the patient qualifies for short-course DAPT (minor stroke or high-risk TIA, or symptomatic intracranial stenosis) with a pre-specified stop date. If cardioembolic, anticoagulate — DOAC for most non-valvular AF, warfarin for the mechanical-valve, LV-thrombus, antiphospholipid, and rheumatic mitral-stenosis exceptions. Throughout, remember that guideline wording, dose thresholds, and institutional protocols vary, and that individual bleeding risk, renal function, and adherence all modify the choice.