The need to quantify right-to-left shunt in acute ischemic stroke: a case-control study

Area of Science:

• Neurology
• Cardiology
• Diagnostic Imaging

Background:

• Right-to-left shunt (RLSh) is linked to stroke, but its significance in unselected acute ischemic stroke populations is unclear.
• Previous studies suggest a higher prevalence in young patients with cryptogenic stroke.

Purpose of the Study:

• To assess the importance of RLSh magnitude as a stroke risk factor in a general population of acute ischemic stroke patients.
• To determine if quantifying RLSh can identify individuals at increased risk.

Main Methods:

• 208 patients with transient ischemic attack/cerebral infarction and 100 controls underwent transcranial Doppler (TCD) with agitated saline.
• RLSh magnitude was quantified via Valsalva maneuver, categorized as no shunt, small (<10 signals), or large (>10 signals, including shower/curtain patterns).
• Logistic regression analysis evaluated RLSh as a stroke risk factor, with extensive investigations for cryptogenic stroke etiology.

Main Results:

• Large RLSh was detected in 19.7% of patients and 21% of controls.
• A large RLSh was significantly more frequent in cryptogenic strokes (45.3%) compared to atherothrombotic (4.7%), cardioembolic (10.5%), and lacunar (15.4%) strokes.
• Shower or curtain patterns of RLSh were associated with a 3.5-fold increased stroke risk (OR 3.5), and a 12.4-fold increased risk for cryptogenic stroke (OR 12.4) after adjusting for risk factors.

Conclusions:

• Quantifying RLSh using contrast TCD during a Valsalva maneuver is essential.
• Only significant RLSh patterns (shower and curtain) are associated with an elevated risk of ischemic stroke in unselected patients.
• These findings highlight the clinical importance of detailed RLSh assessment in stroke evaluation.