Empirical Antimicrobial Therapy and QTc Interval Prolongation in Emergency Medicine

QTc prolongation is common in dangerous clinical conditions, associated with an increased risk of life-threatening arrhythmia torsades de pointes. The goal of this short communication is to evaluate the principal causes of risk of QTc prolongation that are observed in an emergency department and discuss the differences between drug- and non-drug-associated factors.

The retrospective analysis was carried out on 130 patients that presented a QTc prolongation (>480 ms for man and >470 for female, respectively), admitted to the emergency department of a single Italian hospital. Patients with pace-maker (22) were excluded from this study. For each patient, a minimum of 3 ECGs (12 leads) were recorded. Attention was paid on electrolytes disturbances and to the pharmacotherapy, with a particular emphasis to the use of antibiotics.

Mean age of the patients was 79.6 years (SD=11.3) and females and males were almost equally present (46.6% F, 53.7% M). The average QTc value was 492.2 ms (493.3 ms F, 492.8 M). The patients were divided in those with electrolytes disturbances (24.0%), antimicrobial therapy (35.2%), both antimicrobial therapy and electrolytes disturbances (24.1%), and other causes of QTc prolongation (16.7%).

This analysis shows the relevance of the empirical therapy established at the admission, in particular for infective diseases, as an important risk factor for the prolongation of QTc. Other factors that can increase the risk are electrolytes alterations, advanced age, cardiovascular diseases, and drug-drug interaction.