Introduction: A lot of medications regularly used in everyday practice can prolong repolarization period. Unawareness of this deleterious side effect is especially pronounced with combination of such medications. (1-3) The aim of our study was to analyze mortality in patients with QT ≥ 500ms in correlation with QT prolonging medications used.

Methods: 28320 ECGs were recorded and analyzed in a 22-month period. Atrial fibrillation and bundle branch blocks were excluded from the analysis. 680 (2.4%) of ECGs with QT≥ 500ms were analyzed manually. Data on patients and medications used was retrieved from the central hospital data registry and submitted for statistical analysis.

Results: In a period of 301±163 days, all-cause mortality in the cohort of 680 patients was 21% (143/680). QT prolonging medications were grouped as follows: antiarrhythmics 31%, antidepressants 27%, antibiotics 21%, and other. Amiodarone and sotalol were the most common antiarrhythmics used, escitalopram and chlorpromazine the most common antidepressants, while azithromycin and erythromycin were the most frequently used antibiotics. Number of QT prolonging medications was shown to be a predictor of mortality, independent of age and gender (HR 1.23, 95%, CI 1.04, p<0.01). Patients on ≥2 QT prolonging medications had statistically significant increase in mortality (36% vs. 16%).

Conclusion: Increasing awareness of QT prolonging medications and their effect on patient mortality is warranted, especially if more than two QT prolonging drugs are combined.