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Vascular
12 notes available
1 Last Minute Review 2 Cerebrovascular Anatomy 3 Stroke Syndromes 4 Acute Stroke Management 5 Stroke Workup 6 Secondary Prevention 7 Intracerebral Hemorrhage 8 SAH & Aneurysms 9 SDH & EDH 10 Venous Thrombosis 11 Vascular Malformations 12 Special Vascular Topics
Clinical › Vascular

Secondary Prevention

Secondary Stroke Prevention

What You'll Learn

  • Antiplatelet selection: aspirin monotherapy vs. clopidogrel vs. short-term DAPT (CHANCE/POINT) vs. aspirin-dipyridamole
  • Anticoagulation for AF-related stroke: CHA2DS2-VASc scoring, DOAC selection (RE-LY, ROCKET AF, ARISTOTLE, ENGAGE AF), and timing of initiation after acute stroke (1-3-6-12 rule)
  • Carotid stenosis: NASCET grading, symptomatic vs. asymptomatic thresholds, CEA vs. CAS (CREST), and timing of intervention
  • Intracranial atherosclerosis: SAMMPRIS and WASID — aggressive medical therapy is superior to stenting
  • PFO closure indications: RoPE score, CLOSE/RESPECT/REDUCE trials, and patient selection criteria
  • Blood pressure targets: SPS3, SPRINT, and PROGRESS trial results for secondary prevention
  • Statin therapy: SPARCL trial, high-intensity statin indications, and LDL targets
  • Special scenarios: cervical artery dissection (CADISS), dual pathology management, and stroke on anticoagulation
HighYield Pearls
  • Symptomatic ICA stenosis 70–99%: CEA within 2 weeks of TIA/minor stroke (NASCET Level I) — do NOT delay; CAS reserved for high surgical risk or anatomically inaccessible lesions.
  • SAMMPRIS: For symptomatic severe intracranial stenosis 70–99%, aggressive medical therapy (DAPT × 90 d + high-intensity statin + BP <140/90) is SUPERIOR to Wingspan stenting (early stenting worse). WASID addressed 50–99% and showed warfarin was not superior to aspirin.
  • Minor stroke (NIHSS ≤3) or high-risk TIA (ABCD2 ≥4): DAPT (aspirin + clopidogrel 300 mg load → 75 mg) × 21 days then monotherapy (CHANCE/POINT); ticagrelor + ASA × 30 d alternative (THALES).
  • Non-valvular AF: DOAC preferred over warfarin (lower ICH risk); apixaban renal dose 2.5 mg BID if ≥2 of age ≥80, weight ≤60 kg, Cr ≥1.5.
  • Mechanical heart valves and moderate-to-severe rheumatic mitral stenosis: warfarin is required — DOACs are contraindicated (RE-ALIGN halted for harm with dabigatran). INR target varies by valve type/position and risk factors (commonly 2.0–3.0 for aortic, 2.5–3.5 for mitral mechanical). Avoid the “valvular AF” label.
  • 1-3-6-12 day rule: Timing of anticoagulation after cardioembolic stroke — TIA day 1, small stroke day 3, moderate day 6, large day 12; individualize for hemorrhagic transformation risk.
  • Cryptogenic stroke + PFO, age <60, high RoPE: PFO closure + antiplatelet (CLOSE, REDUCE, RESPECT); ESUS without PFO → antiplatelet only (NAVIGATE-ESUS and RE-SPECT ESUS showed NO benefit of anticoagulation).
  • CADASIL and CAA with lobar microbleeds: avoid anticoagulation when possible due to microbleed/ICH risk; individualize if a compelling indication exists (CADASIL alone is not a clean absolute contraindication to IV thrombolysis). Antiplatelet + BP control; consider LAA occlusion (Watchman) if AF.
  • BP target <130/80 (SPS3, SPRINT-MIND); ACEi/ARB + thiazide first-line; AVOID aggressive BP lowering in the acute period.
  • SPARCL / 2021 secondary-prevention guideline: high-intensity statin (atorvastatin 80) recommended in most stroke patients with LDL goal <70 mg/dL; PCSK9 inhibitor if statin-intolerant and high-risk. Reassess risk-benefit in hemorrhagic stroke / probable CAA.
🔍 Quick ReferenceBy mechanism · Medication choice · Procedural / lifestyle
By stroke mechanism
  • Large-artery atherosclerosis, symptomatic ICA 70–99% → CEA within 2 weeks (NASCET)
  • Symptomatic severe intracranial stenosis 70–99% → Aggressive medical therapy — DAPT × 90 d + statin + BP (SAMMPRIS); WASID addressed 50–99% (warfarin not superior to aspirin)
  • Non-valvular AF → DOAC (apixaban / rivaroxaban / dabigatran / edoxaban)
  • Mechanical valves or moderate-to-severe rheumatic mitral stenosis → Warfarin (INR target varies by valve type/position — commonly 2.0–3.0 aortic, 2.5–3.5 mitral mechanical); DOACs contraindicated
  • Small-vessel lacunar disease → Antiplatelet + aggressive BP and glycemic control (SPS3)
  • ESUS (embolic stroke of undetermined source) → Antiplatelet (NAVIGATE-ESUS, RE-SPECT ESUS — anticoag NO benefit)
  • Cryptogenic + PFO + high RoPE + age <60 → PFO closure + antiplatelet (CLOSE / REDUCE / RESPECT)
  • CADASIL → Antiplatelet + BP; avoid anticoagulation when possible due to microbleed/ICH risk (individualize for compelling indications)
  • Moyamoya → Antiplatelet + revascularization (EDAS or STA-MCA bypass)
  • CNS vasculitis → Immunosuppression (steroids ± cyclophosphamide)
Medication choice
  • Aspirin 81 mg daily → Standard non-cardioembolic monotherapy
  • Clopidogrel 75 mg → Aspirin allergy or aspirin failure (CAPRIE)
  • Aspirin + clopidogrel (CHANCE/POINT) → Minor stroke NIHSS ≤3 / high-risk TIA × 21 days
  • Aspirin + ticagrelor (THALES) → Minor stroke / TIA × 30 days alternative
  • Aspirin + dipyridamole (Aggrenox) → Historical option, declining use (ESPRIT, PRoFESS)
  • Apixaban 5 mg BID → Non-valvular AF (2.5 BID if 2+: age ≥80, ≤60 kg, Cr ≥1.5)
  • Dabigatran 150 mg BID → Non-valvular AF, renal dose adjustment (RE-LY)
  • Rivaroxaban 20 mg with dinner → Non-valvular AF, once-daily option (ROCKET AF)
  • Warfarin → Required for mechanical valves and moderate-to-severe rheumatic mitral stenosis (INR target varies by valve type/position)
  • Atorvastatin 80 mg → High-intensity statin recommended in most stroke patients (SPARCL / 2021 guideline; reassess in hemorrhagic stroke / CAA)
Procedural / lifestyle
  • CEA within 2 weeks → Symptomatic 70–99% ICA stenosis (Level I); 50–69% if male/older/recent event
  • CAS (carotid artery stenting) → High surgical risk, anatomically inaccessible lesion, or age <70 (CREST)
  • PFO closure → Cryptogenic stroke, age <60, high RoPE score
  • Watchman / LAA occlusion → Non-valvular AF with high bleeding risk or anticoag contraindication
  • BP target <130/80 → ACEi/ARB + thiazide first-line (SPS3, PROGRESS)
  • LDL <70 mg/dL → High-intensity statin ± ezetimibe ± PCSK9
  • A1c <7% → Diabetes target for secondary prevention
  • Smoking cessation, Mediterranean diet, 150 min/wk exercise, ETOH moderation → Lifestyle bundle
  • CPAP → OSA screening + treatment in stroke survivors
Antiplatelet Therapy

Aspirin Monotherapy

  • Dose: 50–325 mg daily; most guidelines recommend 81–325 mg for secondary prevention
  • Mechanism: Irreversible COX-1 inhibition → decreased thromboxane A2 → reduced platelet aggregation
  • Evidence: Meta-analysis by the Antithrombotic Trialists’ Collaboration showed ~22% RRR in recurrent vascular events with antiplatelet therapy (mostly aspirin-based)
  • No clear dose-response relationship — higher doses (>150 mg) increase GI bleeding risk without additional ischemic benefit
  • AHA/ASA 2021 guideline: Aspirin 50–325 mg/day is recommended for non-cardioembolic ischemic stroke/TIA (Class I, Level A)

Clopidogrel

  • Dose: 75 mg daily (loading dose 300–600 mg when rapid onset needed)
  • Mechanism: Irreversible P2Y12 ADP receptor antagonist on platelets
  • CAPRIE trial (1996): Clopidogrel vs. aspirin 325 mg in patients with recent stroke, MI, or PAD
    • Primary outcome: Composite of ischemic stroke, MI, or vascular death
    • Result: 8.7% RRR favoring clopidogrel (p = 0.043) — marginal but statistically significant
    • Benefit most pronounced in PAD subgroup; stroke subgroup alone did NOT reach significance
  • Reasonable alternative to aspirin for non-cardioembolic stroke; preferred in patients with aspirin allergy or aspirin failure
  • CYP2C19 polymorphisms: Poor metabolizers (~2–14% of population, higher in Asian patients) have reduced clopidogrel activation → consider genotyping or alternative agents (ticagrelor, prasugrel — though prasugrel is not used for stroke prevention)

Dual Antiplatelet Therapy (DAPT) — Short-Term

  • Indication: Minor ischemic stroke (NIHSS ≤3) or high-risk TIA (ABCD2 ≥4) within 24 hours of symptom onset
  • Regimen: Aspirin + clopidogrel for 21 days, then transition to single antiplatelet (clopidogrel monotherapy preferred)

CHANCE Trial (2013)

  • Population: Chinese patients with minor stroke (NIHSS ≤3) or high-risk TIA within 24 hours
  • Intervention: Aspirin + clopidogrel × 21 days then clopidogrel alone vs. aspirin alone × 90 days
  • Result: DAPT reduced stroke recurrence from 11.7% to 8.2% (HR 0.68, p < 0.001) — ARR 3.5%, NNT ~29
  • No significant increase in moderate or severe hemorrhage
  • Limitation: Conducted entirely in China; higher rate of CYP2C19 poor metabolizers in study population

POINT Trial (2018)

  • Population: International (multinational); minor stroke (NIHSS ≤3) or high-risk TIA within 12 hours
  • Intervention: Aspirin + clopidogrel vs. aspirin alone × 90 days
  • Result: DAPT reduced ischemic events at 90 days (5.0% vs. 6.5%, HR 0.75, p = 0.02)
  • But: Increased major hemorrhage (0.9% vs. 0.4%, HR 2.32, p = 0.02) — particularly after day 21
  • Key takeaway: Benefit concentrated in first 21 days; risk increases after → supports 21-day DAPT window (consistent with CHANCE)

THALES Trial (2020)

  • Intervention: Aspirin + ticagrelor vs. aspirin alone × 30 days in minor stroke/high-risk TIA
  • Result: Reduced composite of stroke or death (5.5% vs. 6.6%, HR 0.83, p = 0.02)
  • Increased severe bleeding and higher discontinuation rates
  • Ticagrelor is not first-line for DAPT in stroke but is an option if clopidogrel resistance is suspected
💎 Board Pearl

DAPT (aspirin + clopidogrel) for exactly 21 days after minor stroke (NIHSS ≤3) or high-risk TIA, started within 24 hours. Then switch to clopidogrel monotherapy. Beyond 21 days, bleeding risk outweighs benefit (POINT). CHANCE showed a 3.5% ARR (NNT ~29).

Aspirin-Dipyridamole (Aggrenox)

  • Formulation: Aspirin 25 mg + extended-release dipyridamole 200 mg, taken BID
  • Mechanism: Dipyridamole inhibits phosphodiesterase → increases cAMP → inhibits platelet aggregation; also inhibits adenosine reuptake
  • ESPS-2 (1996): Combination superior to aspirin alone and placebo for secondary stroke prevention (37% RRR vs. placebo)
  • ESPRIT trial (2006): Aspirin-dipyridamole superior to aspirin alone (HR 0.80 for composite vascular events)
  • PRoFESS trial (2008): Aspirin-dipyridamole vs. clopidogrel — non-inferior; no significant difference in stroke recurrence (9.0% vs. 8.8%)
    • Dipyridamole arm had more headaches and GI side effects, leading to higher discontinuation
  • Main side effect: Headache (up to 40%) — often limits tolerability; resolves with continued use in many patients
  • Current status: Largely replaced by clopidogrel due to tolerability; still listed as an acceptable option in AHA/ASA guidelines

When NOT to Use Antiplatelets Alone

  • Cardioembolic stroke (atrial fibrillation) → anticoagulation is superior; antiplatelets are inferior to OAC for AF
  • Mechanical heart valves → warfarin required (DOACs contraindicated — RE-ALIGN trial showed harm with dabigatran)
  • LV thrombus → anticoagulation (warfarin or DOAC) for at least 3 months
  • High-grade intracranial stenosis → DAPT (not single antiplatelet) + aggressive risk factor management (SAMMPRIS protocol)
Clinical Pearl

Aspirin “failure” (recurrent stroke on aspirin) does not necessarily mean aspirin resistance. Reassess the stroke mechanism: was it truly non-cardioembolic? Consider occult AF (prolonged cardiac monitoring), PFO, or previously undetected stenosis before simply switching antiplatelets.

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