10.2 Transient Ischemic Attack, Secondary Prevention & Hemorrhagic Stroke
Key Takeaways
- Transient ischemic attack requires urgent evaluation because early stroke risk is concentrated in the first 48 hours.
- Short-term dual antiplatelet therapy after minor stroke or high-risk transient ischemic attack reduces recurrence and is then narrowed to a single agent.
- Four-factor prothrombin complex concentrate with vitamin K is the fastest reversal for warfarin-associated intracerebral hemorrhage.
- A negative non-contrast computed tomography does not exclude subarachnoid hemorrhage beyond the first hours, so lumbar puncture or vascular imaging is required.
- Nimodipine reduces poor outcome from delayed cerebral ischemia after aneurysmal subarachnoid hemorrhage and is given to all such patients.
1. Post-Stroke Secondary Prevention & Antithrombotic Selection
| Clinical Stroke Subtype | First-Line Antithrombotic Strategy | Clinical Trial Evidence & Rules | Ancillary Pharmacotherapy & Targets |
|---|---|---|---|
| Minor Non-Cardioembolic Ischemic Stroke (NIHSS <=3) OR High-Risk TIA (ABCD2 >=4) | Dual Antiplatelet Therapy (DAPT): Aspirin (162-325 mg load, then 81 mg daily) + Clopidogrel (300-600 mg load, then 75 mg daily) initiated within 24 hours | CHANCE and POINT Trials: Continue DAPT for exactly 21 days, then transition to single antiplatelet therapy (Aspirin or Clopidogrel) indefinitely. (Do not continue DAPT beyond 21-90 days due to excess major hemorrhage without added ischemic benefit) | High-intensity statin (Atorvastatin 80 mg daily per SPARCL trial; target LDL-C <70 mg/dL); Blood pressure goal <130/80 mmHg long-term |
| Moderate-to-Severe Non-Cardioembolic Stroke (NIHSS >=4) | Single Antiplatelet Therapy: Aspirin 81-325 mg daily monotherapy (or Clopidogrel 75 mg daily monotherapy) initiated within 24-48 hours | Standard monotherapy. If patient was treated with IV thrombolysis, delay antiplatelet therapy for 24 hours post-infusion until follow-up CT rules out hemorrhagic transformation | High-intensity statin; Glycemic control (HbA1c <7.0%); Smoking cessation |
| Cardioembolic Stroke (Atrial Fibrillation / Flutter) | Direct Oral Anticoagulants (DOACs): Apixaban 5 mg BID, Rivaroxaban 20 mg daily, or Dabigatran 150 mg BID (preferred over Warfarin) | "1-3-6-12 Day Rule" for DOAC Initiation:<br/>- Day 1: Transient Ischemic Attack (TIA)<br/>- Day 3: Minor stroke (small non-disabling infarct)<br/>- Day 6: Moderate stroke (non-disabling, small-to-medium core)<br/>- Day 12 to 14: Large territorial cortical infarction (repeat CT/MRI at day 12-14 to exclude hemorrhagic conversion prior to starting DOAC) | DOAC dose adjustments for age >=80, weight <=60 kg, or serum Cr >=1.5 mg/dL (Apixaban: 2.5 mg BID if >=2 criteria met) |
| Symptomatic Severe Extracranial Carotid Stenosis (70-99%) | Carotid Endarterectomy (CEA) (or Carotid Artery Stenting [CAS] in high surgical risk anatomy) | NASCET Trial: CEA provides maximal stroke risk reduction when performed within <=14 days of minor stroke or TIA in patients with non-disabling deficits | Single antiplatelet + high-intensity statin prior to and following revascularization |
2. Transient Ischemic Attack (TIA) & The ABCD2 Risk Score
Modern Tissue-Based Definition of TIA
A Transient Ischemic Attack (TIA) is defined as a transient episode of neurological dysfunction caused by focal brain, spinal cord, or retinal ischemia without acute infarction on diffusion-weighted imaging (DWI) MRI. The traditional arbitrary time limit of <24 hours has been superseded by this tissue-based definition: any persistent DWI hyperintensity confirms acute ischemic stroke regardless of symptom duration.
The ABCD2 Risk Stratification Score
The ABCD2 score predicts the 48-hour and 7-day risk of subsequent completed ischemic stroke following a TIA:
- A — Age: >=60 years = 1 point
- B — Blood Pressure: Systolic BP >=140 mmHg OR Diastolic BP >=90 mmHg on initial evaluation = 1 point
- C — Clinical Features:
- Unilateral motor weakness (with or without speech impairment) = 2 points
- Speech disturbance without motor weakness = 1 point
- Other symptoms (isolated sensory loss, dizziness) = 0 points
- D — Duration of Symptoms:
-
=60 minutes = 2 points
- 10 to 59 minutes = 1 point
- <10 minutes = 0 points
-
- D — Diabetes Mellitus: History of diabetes = 1 point
Clinical Interpretation & Inpatient Triage
- Low Risk (Score 0-3): 48-hour stroke risk ~1.0%. May undergo outpatient workup within 24-48 hours if reliable and urgent imaging is available.
- Moderate Risk (Score 4-5): 48-hour stroke risk ~4.1%.
- High Risk (Score 6-7): 48-hour stroke risk ~8.1% (7-day risk ~12%).
ABIM Board Action Rule for TIA: Any patient with an ABCD2 score >= 4, crescendo TIAs, focal weakness, symptom duration >10 minutes, or known high-grade ipsilateral carotid stenosis mandates immediate inpatient hospital admission for continuous telemetry, emergent brain MRI with DWI, vascular imaging (CTA or MRA from aortic arch through vertex), transthoracic/transesophageal echocardiography, and immediate initiation of DAPT (Aspirin + Clopidogrel) for 21 days.
3. Spontaneous Intracerebral Hemorrhage (ICH)
Spontaneous non-traumatic intracerebral hemorrhage accounts for 10-15% of all strokes and carries a 30-day mortality approaching 40-50%.
Etiologies and Anatomical Distribution
- Hypertensive Arteriopathy (Lipohyalinosis & Charcot-Bouchard Microaneurysms):
- Accounts for >65% of primary ICH.
- Predilection Sites: Deep subcortical penetrating arterioles supplying the putamen / basal ganglia (50%), thalamus (15%), pons (10%), and cerebellum (10%).
- Clinical Presentation: Sudden focal deficit progressing over minutes to hours, severe headache, vomiting, elevated blood pressure, and depressed level of consciousness.
- Cerebral Amyloid Angiopathy (CAA):
- Deposition of beta-amyloid in media and adventitia of small-to-medium cortical and leptomeningeal arteries.
- Predilection Sites: Lobar hemorrhages (parietal, occipital, frontal) in elderly patients (>65 years) without preceding hypertension.
- Neuroimaging: Gradient-echo (GRE) or Susceptibility-Weighted Imaging (SWI) MRI reveals multiple cortical-subcortical microbleeds and cortical superficial siderosis.
- Board Rule: Anticoagulation is strictly contraindicated in CAA due to high rates of recurrent fatal lobar ICH.
Emergency Management of Acute ICH
-
Intensive Blood Pressure Lowering (INTERACT-2 & ATACH-2 Trials):
- For patients presenting with SBP between 150 and 220 mmHg, acutely lowering SBP to a target of 130 to 140 mmHg within 1 to 2 hours reduces hematoma expansion and improves functional recovery.
- Caution: Avoid dropping SBP <120 mmHg, which increases acute kidney injury and cerebral hypoperfusion.
- Use continuous IV titratable infusions: Nicardipine (5-15 mg/h) or Labetalol (10-20 mg IV boluses).
-
Immediate Anticoagulant Reversal Protocols:
| Anticoagulant Agent | Immediate Reversal Regimen | Mechanism & Administration Rules |
|---|---|---|
| Warfarin (VKA) | 4-Factor Prothrombin Complex Concentrate (4F-PCC - Kcentra) (25-50 units/kg IV based on baseline INR) PLUS IV Vitamin K (Phytonadione 10 mg) slow IV push | 4F-PCC contains non-activated factors II, VII, IX, X and proteins C/S; normalizes INR within 15-30 minutes. Vitamin K sustains hepatic synthesis. Do NOT rely on FFP (too slow, volume overload) |
| Dabigatran (Direct Thrombin Inhibitor) | Idarucizumab (Praxbind) 5 g IV | Humanized Fab fragment that binds dabigatran with 350x higher affinity than thrombin; administered as two consecutive 2.5 g IV boluses |
| Factor Xa Inhibitors (Apixaban, Rivaroxaban, Edoxaban) | Andexanet alfa (Andexxa) OR 4-Factor PCC (50 units/kg IV) | Andexanet alfa is a recombinant modified human factor Xa decoy protein; 4F-PCC is widely used as a proven alternative if Andexanet is unavailable |
| Unfractionated Heparin (UFH) | Protamine Sulfate | 1 mg per 100 units of heparin administered in past 2-3 hours (max 50 mg IV slow push over 10 min) |
- Neurosurgical Indications for Decompression:
- Cerebellar Hemorrhage >=3 cm in Diameter: Mandates emergent neurosurgical posterior fossa decompression and hematoma evacuation if accompanied by neurological deterioration, brainstem compression, or 4th ventricle obstruction causing acute hydrocephalus. Medical therapy alone in this subset carries prohibitive mortality.
- Supratentorial Hemorrhage: Routine surgical evacuation of deep basal ganglia ICH is NOT recommended; minimally invasive catheter evacuation or decompressive hemicraniectomy is reserved for life-threatening refractory mass effect.
4. Aneurysmal Subarachnoid Hemorrhage (SAH)
Aneurysmal SAH accounts for ~5% of strokes and results from the rupture of intracranial saccular (berry) aneurysms. The most common anatomical locations are the Anterior Communicating Artery (ACom - 30-35%), Posterior Communicating Artery (PCom - 25% - often causing ipsilateral CN III palsy with pupil dilation), and the MCA bifurcation (20%).
Clinical Presentation & Diagnostic Algorithm
- Clinical Hallmark: Sudden, instantaneous onset of excruciating headache peaking within seconds ("thunderclap headache", "worst headache of my life"), accompanied by photophobia, neck stiffness (meningismus), nausea/vomiting, syncope, and Terson syndrome (preretinal subhyaloid retinal hemorrhages on funduscopy).
- Diagnostic Protocol:
- Non-Contrast Head CT: Sensitivity is >98-100% within the first 6 hours of headache onset. Blood appears hyperdense in basal cisterns, sylvian fissures, and sulci.
- Lumbar Puncture (LP): Mandatory if non-contrast CT is negative or non-diagnostic and clinical suspicion remains high. Classic findings:
- Elevated opening pressure (>200 mm H2O).
- Persistent, elevated RBC count in tubes 1 through 4 without clearing (distinguishing SAH from a traumatic tap where RBC counts decline significantly from tube 1 to tube 4).
- Xanthochromia: Pinkish-yellow discoloration of CSF supernatant resulting from enzymatic breakdown of oxyhemoglobin into bilirubin; detected reliably by spectrophotometry >=6 to 12 hours after hemorrhage and persisting for 2 to 4 weeks.
- Vascular Imaging: CTA of the head or Digital Subtraction Angiography (DSA - gold standard) to identify the culprit aneurysm neck morphology and plan endovascular coiling vs surgical clipping.
Major Complications and Inpatient Management
- Aneurysmal Rebleeding: Greatest risk is within the first 24 hours (4-10% rate, associated with >50% mortality). Prevented by urgent aneurysm securement via endovascular coiling or surgical clipping within 24 to 48 hours. Pre-operative SBP should be tightly controlled (<140-160 mmHg).
- Cerebral Vasospasm & Delayed Cerebral Ischemia (DCI):
- Occurs in 30-70% of patients, characteristically developing between days 3 and 14 (peaking at days 7-8) post-hemorrhage due to spasmogenic degradation products (oxyhemoglobin) in the subarachnoid space.
- Mandatory Prophylaxis: Oral Nimodipine 60 mg PO every 4 hours for 21 consecutive days (dihydropyridine CCB that crosses the blood-brain barrier; reduces cerebral infarction and improves neurological outcomes; Class I recommendation).
- Hemodynamic Management: Maintain strict euvolemia with isotonic crystalloids (0.9% Normal Saline). Prophylactic "Triple-H" hypervolemic hemodilution is no longer recommended. If clinical DCI develops (new focal deficit or drop in Glasgow Coma Scale), initiate induced hypertension with IV vasopressors (e.g., Norepinephrine to target MAP 100-110 mmHg). Perform rescue endovascular intra-arterial vasodilators (Nicardipine/Verapamil) or transluminal balloon angioplasty for refractory vasospasm.
- Acute Obstructive / Communicating Hydrocephalus: Managed with emergency placement of an External Ventricular Drain (EVD).
- Hyponatremia in SAH — Cerebral Salt Wasting (CSW) vs SIADH:
- Cerebral Salt Wasting (CSW): Driven by excessive central brain natriuretic peptide (BNP) release causing renal sodium wasting and true intravascular volume depletion (low CVP, orthostasis, high urine Na >40 mEq/L). Treatment is volume expansion with isotonic saline (0.9% NS) or hypertonic saline (3% NaCl) plus oral Fludrocortisone.
- SIADH: Euvolemic hyponatremia.
- CRITICAL BOARD CONTRAINDICATION: Never fluid restrict an SAH patient with hyponatremia. Fluid restriction worsens hypovolemia and drastically precipitates severe cerebral vasospasm, secondary infarction, and death.
A 48-year-old previously healthy man presents to the emergency department reporting the sudden onset of the 'worst headache of his life' that began 8 hours ago while lifting heavy furniture. The headache reached maximum, excruciating intensity within 30 seconds and is accompanied by neck stiffness, photophobia, and repeated vomiting. On physical examination, temperature is 37.4°C (99.3°F), blood pressure is 154/92 mmHg, and heart rate is 82 bpm. He is alert and oriented with marked nuchal rigidity on neck flexion but has no focal motor or sensory deficits. A non-contrast head CT performed immediately on arrival is reviewed by an experienced neuroradiologist and reported as completely normal with no intracranial hemorrhage. What is the most appropriate next diagnostic step?
A 72-year-old woman with a history of persistent non-valvular atrial fibrillation managed with Warfarin presents with sudden-onset headache, nausea, and right-sided hemiparesis. Her vital signs show a blood pressure of 172/98 mmHg and heart rate of 84 bpm. Emergent non-contrast head CT demonstrates an acute 35-mL left basal ganglia intracerebral hemorrhage with 4 mm of midline shift. Her admission laboratory results reveal a prothrombin time (PT) of 36 seconds and an International Normalized Ratio (INR) of 3.4. In addition to titrating IV nicardipine to target a systolic blood pressure between 130 and 140 mmHg, which of the following is the most effective and rapid medical intervention to reverse her coagulopathy?