A Case of Severe QTc Prolongation During Targeted Temperature Management - What Can We Learn?

Abstract

BACKGROUND QTc prolongation during targeted temperature management (TTM) post cardiac arrest is a known effect of hypothermia, but its significance is unclear. Several studies suggest that temporary prolongation during TTM is not prognostic and does not potentiate fatal arrhythmias; however, there are limited cases of patients presenting with QTc intervals >700 milliseconds. CASE REPORT We describe a case in which a 57-year-old woman with diabetes, hypertension, and atrial fibrillation presented with concern for stroke. The hospital course was complicated by cardiac arrest requiring TTM, which was stopped early due to significant QTc prolongation of 746 milliseconds. CONCLUSIONS TTM is beneficial post resuscitation for good neurological outcomes, but it also has known adverse cardiac effects such as QTc prolongation. The significance of QTc prolongation during TTM is unclear as several studies have shown no increased incidence of malignant arrhythmias. One case report in the literature describes the incidence of torsades de pointes due to QTc prolongation during TTM. Further study and guidelines regarding electrocardiogram monitoring are needed to determine the importance of QTc prolongation during TTM.

Figure 1.

Electrocardiogram at time of admission showing normal sinus rhythm with left ventricular hypertrophy and prolonged QTc interval of 486 milliseconds.

Figure 2.

Electrocardiogram after return of spontaneous circulation from pulseless electrical activity/ventricular tachycardia arrest showing atrial fibrillation with rapid ventricular response.

Figure 3.

Telemetry strip showing QTc prolongation of 746 milliseconds, noted at 32.9°C, resulting in termination after 8 hours of therapeutic targeted temperature management.

Figure 4.

Electrocardiogram done 30 minutes after targeted temperature management termination showing QTc prolongation of 612 milliseconds.

Figure 5.

Electrocardiogram done after 16 hours of targeted temperature management cessation and at 36.3°C showing improved QTc prolongation to 503 milliseconds.