Changes in QTc interval in long-term hemodialysis patients

BACKGROUND: Cardiovascular diseases, including sudden cardiac death (SCD), are the leading cause of death in hemodialysis (HD) patients. A prolonged QT interval on the electrocardiogram (ECG) is a risk factor for SCD in HD patients. This study investigated whether the heart rate-corrected QT (QTc) interval becomes prolonged along with dialysis vintage. METHODS: A total of 102 HD patients were retrospectively studied. Their ECG data were analyzed at 1, 4, and 7 years after HD initiation. The control group comprised 68 age-matched individuals who had normal renal function and two available ECG reports at an interval of more than 4 years. QTc was measured according to the Bazett formula. The association between QTc interval and dialysis vintage was studied. Additionally, clinically relevant variables related to QTc duration at 1 year after HD initiation were assessed. RESULTS: Average QTc interval at 4 and 7 years after HD initiation was significantly longer than that at 1 year after HD initiation (443, 445, and 437 ms) (p<0.05). On the other hand, QTc interval in the control group was 425 ms in the first year and 426 ms after an average of 6 years. They had no significant differences, although they were much shorter than that in HD patients. Multivariate regression analysis of baseline variables revealed that the corrected calcium levels (p = 0.041) and diabetes (p = 0.043) were independently associated with longer QTc interval. CONCLUSIONS: The QTc interval at 1 year after HD initiation was longer than in the control subjects and was prolonged over several years of HD treatment. Providing clinical management with a focus on QTc interval may be helpful for reducing the incidence of SCD in HD patients.