Abstract 17010: Predicting Risk of Sudden Death With QT Interval-Prolonging Medications

Abstract

Background: The ongoing pandemic has re-emphasized how QT-prolonging drugs can increase risk of sudden cardiac death (SCD), but azithromycin and hydroxychloroquine are only 2 of many such medications. There remains a critical need to identify individuals who are at high risk of SCD based on their demographic and clinical profile. Hypothesis: A modified Tisdale Score (TS), originally designed to assess risk of QTc (corrected QT interval) prolongation with QT-prolonging drugs, could also predict risk of SCD. Methods: From the ongoing Oregon Sudden Unexpected Death Study (ORESUDS), we identified a subgroup of SCD patients with coronary artery disease (CAD) and controls (individuals with and without CAD but no history of SCD) on at least one QT-prolonging medication enrolled between 2002 and 2020. Analysis was restricted to subjects with available pre-arrest medical history, including ECGs with QT interval available and details of prescribed medications. We identified QT prolonging drugs from the comprehensive list at crediblemeds.com. Our TS included age, sex, use of loop diuretics, serum potassium levels, history of acute myocardial infarction, history of heart failure, and number of QT prolonging drugs. We used a univariate logistic regression to determine the predictive power of the modified TS for SCD. We performed a backwards stepwise logistic regression considering race/ethnicity, diabetes, and hypertension in addition to TS to improve SCD prediction. Results: A total of 964 cases (60% male, mean age 68 years) and 668 controls (62% male, mean age 67 years) met inclusion criteria. TS ranged from 0 to 12 and mean TS was 5.86 ± 2.93 in cases and 4.29 ± 2.74 in controls (p < 0.001). A 1-unit increase in the modified TS was a significant predictor of SCD (odds ratio (OR) 1.21, 95% confidence interval, 1.17 to 1.26). In the multivariable model predicting SCD, both the modified TS (OR 1.20, 95% CI, 1.15 to 1.25) and diabetes (OR 1.42, 95% CI, 1.14 to 1.78) were significant independent predictors of SCD. Conclusion: A modified Tisdale Score predicts SCD, and history of diabetes could potentially enhance the utility of this user-friendly clinical tool. These findings have implications for prescription of QT-prolonging drugs, especially during the ongoing pandemic.