Life-threatening cardiac arrhythmias due to drug-induced QT prolongation : A retrospective study over 6 years from a medical intensive care unit.
BACKGROUND
Long QT syndrome (LQTS) can lead to ventricular arrhythmia, especially torsade de pointes (TdP) tachycardia and/or ventricular tachycardia (VT). The aim of this study is to characterize patients with life-threatening cardiac arrhythmias associated with drug-induced LQTS and to identify risk factors of distinct presenting arrhythmias.


METHODS
In this retrospective study, we present 33 consecutive cases of life-threatening cardiac arrhythmias associated with drug-induced long QT, which were direct admitted as emergency to a medical intensive care unit (MICU) during an observational time of 6 years.


RESULTS
Of 33 identified cases, 55 % presented with TdP with the need of resuscitation and 45 % showed nonsustained VT, respectively. In the total cohort the mean corrected QT interval (QTc) was 532 ± 29 ms, with 530 ± 31 ms (n = 14) in men and 533 ± 28 ms (n = 19) in women (p = 0.80), respectively. Cardiac drugs with QTc interval prolonging effect were reported in 24 % of cases, and the other 76 % involved noncardiac medications. Although hypokalemia is the most common risk factor for drug-induced malignant arrhythmias, a QTc interval of at least 500 ms seems to be the major determinant of the risk of drug-induced proarrhythmias. Interestingly, patients with TdP exhibit more bradycardia as such with VT.


CONCLUSIONS
This is the first study of patients with drug-induced life-threatening cardiac arrhythmias who were admitted as a case of emergency to a MICU. Physicians should be aware of drug-induced LQTS and be able to identify patients at risk and avoid specific drugs in such patients.
Department III of Internal Medicine, University of Cologne, Kerpener-Str. 62, 50937, Cologne, Germany. guido.michels@uk-koeln.de.
G
G
Michels
Department I of Internal Medicine, University of Cologne, Cologne, Germany.
M
M
Kochanek
Department III of Internal Medicine, University of Cologne, Kerpener-Str. 62, 50937, Cologne, Germany.
R
R
Pfister
D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D005260:Female; D006801:Humans; D007362:Intensive Care Units; D008133:Long QT Syndrome / Q000139:chemically induced* / Q000628:therapy*; D008297:Male; D008875:Middle Aged; D012151:Resuscitation; D012189:Retrospective Studies; D012307:Risk Factors
Drug-induced LQTS; Drug-induced ventricular arrhythmias; Life-threatening cardiac arrhythmias; QT prolongation