Epinephrine test in a patient with aquired long QT syndrome after ceftazidime administration

Introduction: Long QT syndrome (LQTS) is characterized by congenital or acquired prolongation of the QT interval on ECG. The definition of the LQTS by the European Society of Cardiology (ESC) is: 1) Corrected QT interval (QTc) >480 ms on repeated ECG’s or LQTS risk score above 3 OR 2) Confirmed pathogenic LQTS mutation, irrespective of the QT duration OR 3) QTc >460 ms in the presence of unexplained syncope. Many of those with acquired LQTS were shown to also have an underlying genetic abnormality of the repolarization, making them more vulnerable to sudden cardiac death (SCD). Acquired LQTS may be caused by drugs, electrolyte abnormalities, starvation and neurological injury. This case report intends to briefly discuss and review drug-induced LQTS, especially the one induced by antibiotics.
Case presentation: We report a case of a 62-year-old woman, admitted in a small city cardiology ward for an unexplained syncope. She was on treatment with Ceftazidime for respiratory pathology. After one week of hospitalization the patient presented 10 Vfib episo-des with cardiac arrest necessitating intubation and mechanical ventilation, being transferred to a hospital with intensive care unit. At admission, QTc was 660 ms. During the next week the patient presented 20 torsades des pointes episodes with R/T debut, 7 of them degenerating into Vfib necessitating electrical cardioversion. After stopping Ceftazidime, QTc lowered to 520-530 ms and there were no more malignant ventricular tachycardia episodes. In this context, she was transferred to our cardiology department for ICD therapy. We per-formed EPS and epinephrine test using Mayo protocol, resulting in a decrease of the QTc with low dose and further decrease with high dose epinephrine, excluding LQTS type 1. Taking into account the persistence of prolonged QTc after Ceftazidime cessation and the multiple malignant ventricular arrhythmias episodes that necessitated intubation and mechanical ventilati-on, we opted for the implantable cardiac defibrillator (ICD) therapy.
Conclusions: To summarize all the above mentioned, we can assert that: 1. Ceftazidime is related to QTc interval prolongation on ECG and may be associated with increased rates of ventricular arrhythmias and sudden cardiac death, even though present literature suggests it is a safe option. 2. Epinephrine test is an useful test for excluding type 1 LQTS in the absence of genetic tests. 3.ICD therapy may be the best treatment option in patients with LQTS of unclear etiology which presented multiple resuscitated sudden cardiac death episodes.

ISSN – online: 2734 – 6382
ISSN-L 1220-658X
ISSN – print: 1220-658X
The Romanian Journal of Cardiology is indexed by:
ESC search engine
CODE: 379
CME Credits: 10 (Romanian College of Physicians)