What are the guidelines for using antihypertensives (blood pressure lowering medications) in acute ischemic stroke?

Antihypertensive Management in Acute Ischemic Stroke

In acute ischemic stroke, do NOT lower blood pressure unless it exceeds 220/120 mmHg (or 185/110 mmHg if giving thrombolysis), as aggressive BP reduction can worsen cerebral perfusion and expand infarct size. 1

For Patients NOT Receiving Reperfusion Therapy

BP <220/120 mmHg

• Withhold all antihypertensive medications during the first 48-72 hours 1
• This approach is a Class III recommendation (no benefit) from the ACC/AHA—actively lowering BP in this range does not prevent death or dependency 1
• Cerebral autoregulation is impaired after stroke, making the ischemic penumbra directly dependent on systemic BP for perfusion 1, 2

BP ≥220/120 mmHg

• Lower BP cautiously by approximately 15% over the first 24 hours 1
• This is a Class IIb recommendation (uncertain benefit), but extreme hypertension risks encephalopathy, cardiac complications, and renal damage 1
• Use easily titratable IV agents: labetalol (10-20 mg IV bolus, may repeat) or nicardipine (start 5 mg/hr, titrate by 2.5 mg/hr every 5-15 minutes to max 15 mg/hr) 1, 3
• Avoid precipitous drops >70 mmHg, which can cause acute renal injury and early neurological deterioration 1

For Patients Receiving IV Thrombolysis (tPA)

Pre-Treatment Requirements

• BP must be <185/110 mmHg before administering tPA 1
• If BP is elevated, use labetalol 10-20 mg IV over 1-2 minutes (may repeat once) or nicardipine infusion 5 mg/hr titrated up 1, 3
• Do not give tPA if BP cannot be controlled below 185/110 mmHg 1

Post-Thrombolysis Management

• Maintain BP <180/105 mmHg for at least 24 hours after tPA administration 1
• Monitor BP every 15 minutes for 2 hours, then every 30 minutes for 6 hours, then hourly for 16 hours 1
• High BP during the first 24 hours after tPA significantly increases risk of symptomatic intracranial hemorrhage 1

If systolic BP 180-230 mmHg or diastolic 105-120 mmHg:

• Labetalol 10 mg IV over 1-2 minutes, may repeat every 10-20 minutes (max 300 mg), OR
• Labetalol 10 mg IV bolus followed by continuous infusion 2-8 mg/min, OR
• Nicardipine 5 mg/hr IV, titrate by 2.5 mg/hr every 5 minutes to max 15 mg/hr 1, 3

If diastolic BP >140 mmHg:

• Consider sodium nitroprusside 0.5 mcg/kg/min IV infusion, titrated to effect 1

For Patients Receiving Mechanical Thrombectomy

• Apply the same BP targets as for IV thrombolysis: <180/105 mmHg before and for 24 hours after the procedure 1
• Evidence is limited, but the increased risk of reperfusion injury and hemorrhage justifies proactive BP management 1

Timing of Antihypertensive Initiation/Reinitiation

First 72 Hours

• For patients with BP <180/105 mmHg who did not receive reperfusion therapy, do NOT introduce or reintroduce BP medications 1, 2
• Premorbid antihypertensives should be temporarily discontinued or reduced to prevent unpredictable responses during acute stress 1

After 3 Days (≥72 Hours)

• For neurologically stable patients with BP ≥140/90 mmHg, restart or initiate antihypertensive therapy 1, 4
• This is a Class IIa recommendation (reasonable to do) for improving long-term BP control 1
• After 3 days, the risk of cerebral hypoperfusion decreases while benefits of BP control for secondary prevention become relevant 4

Before Hospital Discharge

• All patients with ischemic stroke/TIA and an indication for BP lowering should have antihypertensive therapy commenced before discharge 1
• Preferred agents: thiazide diuretic, ACE inhibitor, ARB, or combination of thiazide plus ACE inhibitor 1

Preferred Medications for Acute BP Lowering

First-line agents: 1, 2, 5

• Labetalol: Easily titratable, minimal cerebral vasodilatory effects, preferred unless contraindicated (asthma, bradycardia, heart failure)
• Nicardipine: Alternative to labetalol, especially useful in patients with bradycardia or reactive airway disease

Avoid:

• Sublingual nifedipine: Causes precipitous, uncontrolled BP drops 1
• Sodium nitroprusside (except as last resort): Adverse effects on cerebral autoregulation and may increase intracranial pressure 5

Critical Pitfalls to Avoid

1. Treating BP <220/120 mmHg in non-thrombolysis patients during first 48-72 hours—this is ineffective and potentially harmful 1, 2

2. Rapid or excessive BP reduction—can extend infarct size by compromising collateral flow to the penumbra 1, 5

3. Forgetting to restart antihypertensives after day 3—delays secondary prevention and increases recurrent stroke risk 1, 4

4. Using long-acting or unpredictable agents—makes it difficult to reverse if neurological worsening occurs 1

5. Ignoring the 185/110 mmHg threshold before thrombolysis—this is an absolute contraindication to tPA administration 1