Vnitr Lek 2006, 52(3):271-273

Extension of QT interval as a consequence of risk factor accumulation - case study

M. Šišáková^1,*, O. Toman¹, A. Floriánová¹, J. Kadlecová², K. Chroust³, I. Papoušek³, J. Špinar¹

¹ Interní kardiologická klinika Lékařské fakulty MU a FN Brno, pracoviště Bohunice, přednosta prof. MUDr. Jindřich Špinar, CSc., FESC

² Oddělení lékařské genetiky FN Brno, pracoviště FDN J. G. Mendela, přednostka prim. MUDr. Renata Gaillyová

³ Katedra genetiky a molekulární biologie Přírodovědecké fakulty MU Brno, přednosta prof. RNDr. Jiří Doškař, CSc.

Background:
Many non-cardiovascular drugs have a potential for QT interval prolongation. This phenomenon can be related to occurence of ventricular tachycardia torsades de pointes, syncopi and even sudden death. Description of the case: A female patient treated with antracycline cytostatics developed a depression of left ventricle ejection fraction. At the same time she was administered 2 common drugs with proarrhythmic potential - terfenadine and itraconazole. In this patient hypokalemia also occured. Combination of the above mentioned risk factors led to QT interval prolongation and frequent ventricular tachycardias torsades de pointes degenerating in ventricular fibrillations with need of repeated defibrillations. Both drugs were withdrawn and dysiontaemia corrected. Then arrhythmias disappeared and QT interval completely normalized. In this patient the congenital long QT syndrome was not proved.


Discussion and conclusions:
In proarrhythmic effect of non-cardiovascular drugs the following factors play role: predisposition of a particular individual, "repolarization reserve", interindividual differences in drug metabolism. The risk factors are age, sex, dysiontaemia, heart disease and drug interactions. By different choice of medication and attention to risk factors teh life threat to the described patient could have been avoided.

Keywords: proarrhythmia; QT interval prolongation; sudden death

Received: October 5, 2005; Accepted: December 14, 2005; Published: March 1, 2006  Show citation