What is the meaning of a hyperacute infarct?

Meaning of Hyperacute Infarct

A hyperacute infarct refers to a stroke in the earliest time window after symptom onset—specifically the first 24 hours for ischemic and hemorrhagic stroke, and up to 48 hours for transient ischemic attack (TIA)—when time-sensitive interventions like thrombolysis and endovascular therapy can salvage brain tissue and dramatically improve outcomes. 1

Temporal Definition

The term "hyperacute" has a precise clinical meaning that defines treatment windows and urgency:

• For ischemic and hemorrhagic stroke: The first 24 hours after symptom onset 1
• For TIA: The first 48 hours after symptom onset 1
• Clinical context: This encompasses all prehospital care, emergency department assessment, initial stabilization, diagnostic imaging, and acute reperfusion therapies 1

Clinical Significance: "Time is Brain"

The hyperacute period is defined by its extreme time sensitivity because neuronal death occurs rapidly:

• Every minute of untreated ischemic stroke: 1.9 million brain cells die, along with 13.8 billion synapses and 12 km of axonal fibers 1
• Every hour without treatment: The brain ages the equivalent of 3.6 years 1
• Every 30-minute delay in reperfusion: Decreases the chance of good functional outcome by 8-14% 2

This biological urgency is why the Canadian Stroke Best Practice Recommendations emphasize that hyperacute care is "time sensitive by nature, minutes for disabling stroke and hours for TIA" 1

What Happens During the Hyperacute Phase

The hyperacute period encompasses specific critical interventions:

Assessment and Diagnosis

• Rapid neurological evaluation using standardized scales (NIHSS) 2, 3
• Immediate brain imaging (CT or MRI) to differentiate ischemic from hemorrhagic stroke 2, 3
• Vascular imaging (CTA, MRA) to identify large vessel occlusions amenable to endovascular therapy 2
• Determination of "last known well time"—the single most important factor for treatment eligibility 1

Time-Sensitive Treatments

• Intravenous thrombolysis (tPA): Most effective within 3 hours, with benefit extending to 24 hours in selected patients using perfusion imaging 2, 4
• Endovascular thrombectomy: Beneficial up to 24 hours for large vessel occlusions 2, 4
• Emergency neurosurgical procedures: For hemorrhagic stroke complications 1
• Blood pressure management: Critical differences between ischemic (permissive hypertension unless >220/120 mmHg) and hemorrhagic stroke (target <140 mmHg systolic) 2, 3

Pathophysiological Context

During the hyperacute window, there exists a penumbra—ischemic but potentially salvageable tissue surrounding the infarct core:

• This penumbral tissue receives sufficient blood flow to survive temporarily but not enough to function 5
• Imaging evidence shows salvageable tissue may exist for 7-16 hours or even up to 24 hours in some patients 5
• The acute relative cerebral blood flow (rCBF) lesion most accurately identifies tissue at risk of infarction in the PWI>DWI mismatch region 6

Common Pitfalls in Hyperacute Management

Critical errors to avoid:

• Delaying imaging or treatment decisions while waiting for additional diagnostic tests—imaging should occur immediately, not "within 24 hours" but "as soon as possible" 2
• Aggressively lowering blood pressure in acute ischemic stroke, which reduces cerebral perfusion and expands infarction 2
• Using sublingual nifedipine or other agents causing precipitous blood pressure drops 2
• Failing to recognize early neurological deterioration, which is common in the first few hours, particularly in hemorrhagic stroke where 20% of patients experience a decrease in Glasgow Coma Scale of ≥2 points between prehospital and ED evaluation 3, 7
• Overlooking the door-to-needle time target: The updated recommendation is a median of 30 minutes (90th percentile 60 minutes) for tPA administration 1

System-Level Implications

The hyperacute designation requires coordinated workflows:

• Prehospital notification by EMS with detailed patient information to activate stroke teams before arrival 1
• Specialized stroke units or ICUs with neuroscience expertise for monitoring 2, 3
• Interdisciplinary teams including paramedics, ED physicians, stroke neurologists, and neurointerventionalists working in seamless coordination 1

The fundamental principle is that hyperacute stroke care represents a narrow window where aggressive, time-sensitive interventions can prevent permanent disability and death—making every minute count in a way that distinguishes it from all other phases of stroke care 1, 2.