A case of atrial tachycardia sensitive to increased caffeine intake

A 33-year-old Japanese man with atrial tachycardia visited our clinic. He regularly consumed daily alcohol with cola, one cup of regular coffee, and a candy containing 0.7 mg of caffeine per tablet. After stopping his caffeine intake, his arrhythmia ameliorated. Since caffeine might be associated with his arrhythmia, a caffeine load test (equivalent to his daily intake of caffeine) was performed for 4 days. Atrial tachycardia time from a Holter recording was 44.2 minute/day before the caffeine load, compared with 215.2 minute/day during the caffeine load. Plasma caffeine concentration before and during caffeine loading was 3.1 mg/dL and 5.4 mg/dL, respectively. Caffeine use seemed to be an important factor for his atrial tachycardia, since his arrhythmia became worse during caffeine load testing and was ameliorated after the cessation of caffeine.