Relationship between anemia and the risk of Sudden cardiac arrest ― A nationwide cohort study in South Korea ―

Background: The relationship between anemia and sudden cardiac arrest (SCA) is unclear in the general population, so we assessed it in a nationwide cohort. Methods and Results: We studied 494,948 subjects (mean age, 47.8 years; 245,333 men [49.6%]) with national health check-up data from the Korean National Health Insurance Database Cohort. During a mean follow-up period of 5.4 years, SCA occurred in 616 participants (396 men, 220 women). The incidence rates of SCA increased across the 4 anemia groups in both men (0.3, 1.5, 5.3, and 4.5 per 1,000 person-years) and women (0.2, 0.5, 0.5, and 1.2 per 1,000 person-years). The SCA risk per 1-unit decrease in hemoglobin (Hb) increased by 21% and 24%, respectively, in multivariable models adjusted for cardiovascular factors, in men (95% confidence interval [CI], 13–29%; P<0.001) and women (95% CI, 13–37%; P<0.001). A negative correlation between QTc interval and Hb level was observed in men, and a trend was observed in women. Conclusions: Anemia was associated with an increased risk of SCA even after accounting for concomitant conditions in a South Korean nationwide cohort. The correlation between anemia and SCA might be explained by an increase in arrhythmic risks, such as QTc prolongation.