Relative Bradycardia in Scrub Typhus.

To investigate the relationship between heart rate and temperature, we examined 493 febrile patients with documented disease. These patients were diagnosed serologically and analyzed retrospectively: 337 (68.4%) responded to fever with increased heart rate < 10 beats/minute/°C (relative bradycardia [RB]), and 156 patients had a heart rate response ≥ 10 beats/minute/°C (general heart rate increase [GHRI]). The RB group had a higher median resting heart rate and lower heart rate at maximum temperature than the GHRI group. Despite differences in heart rate response, no significant differences were seen in clinical outcomes (acute kidney injury, systemic inflammatory response syndrome (SIRS), and death). We concluded that most patients with scrub typhus presented with RB. In scrub typhus infection, RB can be included as one of the clinical features for differential diagnosis from other infectious diseases.