QT prolongation predicts all-cause mortality above and beyond a validated risk score

QT prolongation is a risk factor for life-threatening arrhythmias and sudden cardiac death. In large cohorts, QT interval was associated with all-cause mortality, but these analyses may contain residual confounding. Whether the QT interval provides prognostic information above and beyond a validated mortality risk score is unknown. We hypothesized that QT interval on ECG will independently predict mortality after adjustment for the Care Assessment Needs (CAN) score, which was validated to predict mortality nationwide at the Veterans Administration (VA) (c-index 0.86). Outpatients with an ECG at the Minneapolis VA from 2012 to 2016 were included in this retrospective cohort study. ECGs with ventricular rate 100 beats/min and those with QRS > 120 ms were excluded. QT intervals were corrected (QTc) using the Bazett's formula. CAN score, calculated within 1-week of the ECG, was obtained from the VA Corporate Data Warehouse. Of the 31,201 patients, 427 (1.4%) had QTc ≥ 500 ms, 1799 (5.8%) had QTc 470–500 ms and 28,975 (92.9%) had QTc