Should Right-to-Left Shunts Be Detected Before Thrombolysis in Acute Ischemic Stroke Patients?

To the Editor: We read with great interest the recent study by Kimura et al regarding the dramatic improvement with intravenously administered tissue plasminogen activator (IV-tPA) in patients with right-to-left shunts (RLS) detection by contrast-enhanced transcranial Doppler (TCD).1 The authors compared the rates of dramatic improvement (defined as a ≥10-point reduction in the total National Institutes of Health Stroke Scale (NIHSS) score or a total NIHSS score of 0 or 1 at 7 days after tPA infusion) between patients with and without RLS and found that patients with RLS more frequently had dramatic improvement (64.7% versus 32.3%; P =0.030). Importantly, in a multivariate model presence of RLS (odds ratio, 5.9; 95% CI, 1.3 to 27.3; P =0.022) was found to be the only independent factor associated with dramatic improvement. The results of this article are thought-provoking. tPA has a short half-life and is rapidly metabolized by …