U-shaped association between variability of remnant cholesterol and risk of cardiac conduction block

Abstract Objective To investigates the association between the variability of remnant cholesterol (RC) during long-term follow-up and cardiac conduction block (CCB) based on the Kailuan cohort. Methods A retrospective study was conducted on the research cohort in the Kailuan study population who consecutively participated in the physical examinations of 2006, 2008, and 2010. Based on the inclusion and exclusion criteria, 39 299 subjects were ultimately enrolled in the study. The variability of RC during the follow-up period was calculated, with the variability assessed through standard deviation (SD), average real variability (ARV), coefficient of variation (CV), and variability independent of the mean (VIM). The participants were divided into 4 groups based on the interquartile range of RC variability, and followed up every 2 years. The endpoints were defined as the occurrence of CCB, death, or the termination of follow-up (December 31, 2019). Kaplan-Meier test and Log-Rank test were carried out respectively calculate and compare the cumulative incidence rate of endpoint events across groups. Cox proportional hazards model and restricted cubic spline (RCS) analysis were performed to analyze the association between the variability of RC and CCB and its subtypes. Results After an average follow-up of 7.43 years in 39 299 participants, 916 patients developed CCB. After adjusting for confounding factors, using CCB as the outcome event, and were dividing the participants into groups based on the RC-SD quartiles, the hazard ratios (HR) for CCB occurrence were 1.344 in the Q1 group (95% CI: 1.110~1.626, P=0.002), 1.068 (95% CI: 0.878 to 1.299, P=0.509) in the Q3 group and 1.311 (95% CI: 1.089~1.579, P=0.004) in the Q4 group, when compared to the group of lowest incidence density (the Q2 group). Similar results were obtained for the quartiles of RC-ARV, RC-CV, and RC-VIN grouping. RCS analysis revealed a U-shaped association between RC-SD and CCB (Poverall