Abstract 12178: Association Between QT Prolongation and Cardiovascular Mortality in Cancer Patients

Abstract

Introduction: The QT interval (QT) is a safeguard criterion to avoid detrimental arrhythmias. Cancer patients are vulnerable to QT prolongation. However, its prognostic impact on cardiovascular (CV) mortality in cancer patients is not clear. Research questions: Which is the best QTc formula to predict CV mortality in cancer patients? Whether a QT interval would be a suitable predictor for CV mortality in cancer patients? Methods: This retrospective observational cohort included adult cancer patients who had an electrocardiogram (ECG) performed in a tertiary hospital in Taiwan. The first performed ECGs after cancer diagnosis (n=59,568) were analyzed. The corrected QT intervals by Bazett (QTcB), Fridericia (QTcFri), and Framingham (QTcFra) formulae were used to predict the 90-day and one-year CV mortality according to the Taiwan death registry. Results: The AUC of QTcB (0.70) for predicting CV mortality at 90 days was better than QTcFri and QTcFra (0.63 and 0.50). The AUC of QTcB (0.68) for predicting CV mortality at one year was also better than QTcFri and QTcFra (0.65 and 0.56).Using the restricted cubic spline regression model adjusted by age and comorbidities, QTcB increased a significant but trivial risk of CV mortality at 90 days (hazard ratio, 1.007, P= 0.02) and one year (1.006, P <0.01). Compared to those with QTcB <500ms, the patients with QTcB ≥500ms were older, had more comorbidities, and higher CV (1.74%), cancer (24.5%), and all-cause mortalities (32.5%) within one year. The incidence of sudden death and ventricular arrhythmias was only 0.2%. After adjusting for comorbidities, QTcB was neither associated with 90-day nor one-year CV mortality. Conclusions: Rather than a long QT interval per se, comorbidities contributed to CV mortality and irreversible outcome in cancer patients.