Background and Purpose— The risk of stroke in patients with short-run atrial tachyarrhythmia (AT) remains unclear. This study aimed to investigate the relationship between short-run AT and the stroke and the use of the CHA ₂ DS ₂ -VASc score for the risk stratification. Methods— From the registry of 24-hour Holter monitoring, 5342 subjects without known atrial fibrillation or stroke were enrolled. Short-run AT was defined as episodes of supraventricular ectopic beats <5 seconds. Results— There were 1595 subjects (29.8%) with short-run AT. During the median follow-up period of 9.0 years, 494 subjects developed new-onset stroke. Patients with short-run AT had significantly higher stroke rates compared with patients without short-run AT (11.4% versus 8.3%; P <0.001). In patients with short-run AT, the number of strokes per 100 person-years for patients with CHA ₂ DS ₂ -VASc score of 0 and 1 were 0.23 and 0.67, respectively. However, the number of them for patients with CHA ₂ DS ₂ -VASc score of 2, 3, 4, and ≥5 were 1.62, 1.89, 1.30, and 2.91, respectively. In patients with CHA ₂ DS ₂ -VASc score of 0 or 1, age (>61 years old) and burden of premature atrial contractions (>25 beats/d) independently predicted the risk of stroke. In subgroup analyses, short-run AT patients were divided into 3 groups based on their CHA ₂ DS ₂ -VASc scores: low score (score of 0 [men] or 1 [women]; n=324), intermediate score (score of 1 [men] or 2 [women]; n=275), and high score (score of ≥2 [men] or ≥3 [women]; n=996). When compared with low score, intermediate and high scores were independent predictors for stroke (hazard ratio, 6.165; P <0.001 and hazard ratio, 8.577; P <0.001, respectively). Conclusions— Short-run AT increases the risk of stroke. Therefore, the CHA ₂ DS ₂ -VASc score could be used for the risk stratification. Age and burden of premature atrial contractions were independent predictors for stroke in patients with CHA ₂ DS ₂ -VASc score of 0 or 1.