New-onset atrial fibrillation predicting for complicating cardiac adverse outcome in scrub typhus infection

Background Scrub typhus is a well-known infectious disorder of the Asia-Pacific region. However, adverse cardiac outcomes are an under-recognized complication of scrub typhus infection, and new-onset AF has been reported to be a prognostic factor in other, more common infectious diseases. The present study investigated whether new-onset atrial fibrillation (AF) is significantly associated with 3-month mortality and adverse cardiac complications in scrub typhus infection. Methods We examined data from the National Health Information Database (NHID) which covers nearly the entire population of South Korea, from 2006 to 2016. In total, 233 473 patients diagnosed with scrub typhus infection were selected as study participants. New-onset AF, acute heart failure (AHF), ischemic heart disease (IHD), and 3-month mortality were analyzed using a generalized estimating equation model with a Poisson distribution. Results Of these, 2402 patients (1%) were diagnosed with new-onset AF (87.2% were over 60 years of age, 43.3% were male). Those with new-onset AF were more likely to have underlying cardiovascular disease compared to those without new-onset AF. After being adjusted for demographic factors and comorbidities, those with new-onset AF had a higher incidence risk of concurrent AHF (4.1-fold) and IHD (1.9-fold) compared with those without new-onset AF. In particular, the 3-month mortality was also significantly associated with new-onset AF (1.3-fold), concurrent AHF (2.4-fold), and IHD (13.7-fold). Conclusions New-onset AF was significantly associated with 3-month mortality and concurrent AHF and IHD. Therefore, new-onset AF could be a poor prognostic factor for 3-month mortality and cardiac complications in scrub typhus infection.