Nearly all left atrial thrombi may be extended from pulmonary vein thrombi

Ischemic stroke is a serious clinical problem [1,2]. To prevent ischemic stroke, it is crucial to identify clinical targets. Left atrial thrombus is a known cause of ischemic stroke [2,3]; however, the cause of left atrial thrombus remains unknown. Pulmonary vein thrombosis (PVT) is thought to be rare; however, I have published several cases of PVT in elderly patients with chest pain using a 64-slice multidetector CT (64-MDCT) since 2012 [4–10]. In 2014, I reported that 61% (35 patients) of 57 elderly patients with chest pain had PVT, as assessed using 64-MDCT, which suggests that PVT is common in elderly patients with chest pain [9]. Although I have reported that a thrombus in the pulmonary vein extends into the left atrium [5,6,8,9], the relationship between PVT and a left atrial thrombus remains unknown. I reviewed the images of 64-MDCT scans obtained from 35 patients with PVT. Seventeen patients (49%) had a thrombus in the left atrium, which was extended from pulmonary vein thrombi, indicating that approximately half of patients with PVT had a left atrial thrombus. In addition, among the 22 patients without PVT, only three patients (14%) had a left atrial thrombus. These three patients may have a fine pulmonary vein thrombus, which could not be clearly visualized using 64-MDCT. Thus, there is a possibility that nearly all left atrial thrombi are extended from pulmonary vein thrombi. Nearly all left atrial thrombi may use pulmonary vein thrombi as a root, which may provide a strong structure in the thrombi. In addition, I reported that some of the thrombi were partially dissolved within three months following warfarin [4] and dabigatran [7–9] treatment, indicating that warfarin and dabigatran could prevent ischemic stroke by dissolving the pulmonary vein thrombus and the connected left atrial thrombus. However, not all thrombi were dissolved upon warfarin [5] and dabigatran [10]