#3282 ASSOCIATION OF PROLONGED QT INTERVALS WITH MORTALITY IN HEMODIALYSIS PATIENTS: A NATIONWIDE RETROSPECTIVE COHORT STUDY
Authors: Sasaki Sho , Fujisaki Kiichiro , Nishimura Masato , Nakano Toshiaki , Joki Nobuhiko 
Published: June 2023

Abstract

Background and Aims
The prevalence of prolonged QT intervals is known to be prevalent among hemodialysis patients. In the general population, prolonged QT intervals are linked to increased mortality, however, the correlation between prolonged QT intervals and prognosis in hemodialysis patients remains uncertain. The objective of this study was to investigate the association between prolonged QT intervals and mortality and cardiac death among hemodialysis patients.

Method
We conducted a retrospective cohort study using the JSDR2019-2020, a nationwide registry of hemodialysis patients in Japan. We excluded from these subjects those younger than 18 years, with QT interval deficit, dialysis less than 3 times a week, atrial fibrillation, peritoneal dialysis, and home dialysis. In 2019, we collected data on various factors and basic patient information, and subsequently monitored outcomes in 2020. QT intervals were corrected using Bazett's formula. Our primary and secondary outcomes were death and cardiac death which we defined as a composite of heart failure, pulmonary edema, arrhythmia, ischemic heart disease, and acute myocardial infarction, respectively. We performed univariate and multivariate analyses of the relationship between QT interval categories and outcomes using logistic regression models, adjusting for age, gender, cause of end-stage renal failure, serum concentrations of iron, potassium, magnesium, calcium, and phosphorus, history of dialysis, and history of cardiovascular disease. We also created a restricted cubic spline to visualize the relationship between QT intervals and outcomes. We employed multivariate imputation by chained equations to complement missing values. We set the significance level at 5%.

Results
Of the 332,599 patients in the database, 198,624 were included in the analysis of this study. The mean (standard deviation: SD), median (quartiles), and actual number (%) of subjects were: age 69.8 (12.4), 130,735 (65.8) male, 101,988 (51.3) with diabetes, and 66.0 (29.0, 128.0) months of dialysis history. The mean QT interval (SD) was 450.7 msec (30.5). During the 1-year observation period, there were 29,705 deaths, 7,247 cardiac deaths, and 12,166 new cases of ischemic heart disease. The odds ratios (95% confidence intervals: 95%CI, p value) for death within 1 year in the three QT interval categories (&lt;460 [reference], 460&lt; = &&lt;500, 500&lt;) were 1(−), 1.58 (1.52-1.64, p&lt;0.001), and 2.49 (2.35-2.62, p&lt;0.001), respectively. In multivariate analysis, the adjusted odds ratios for death within 1 year in each QT interval category were 1(−), 1.44 (1.37-2.12, p&lt;0.001), and 1.98 (1.87-2.09, P&lt;0.001), respectively. Our analysis of cardiac death as an outcome also revealed a statistically significant increase in cardiac death with increasing QT intervals.

Conclusion
QT intervals were prolonged in hemodialysis patients, and prolonged QT intervals were significantly associated with increased mortality and cardiac death.