QRS alternans in paroxysmal supraventricular tachycardia

Lee, H I; Lee, M Y; Kim, J K; Seo, Y M; Kang, I J; Mun, K W; Jin, S W; Rho, T H; Hong, S T; Choi, K B

Abstract

BACKGROUND: The pheonomenon of QRS alternans in paroxysmal supraventricular tachycardia (PSVT) has been of continuing interest to cardiologists. However, the underlying mechanism and related factors of QRS alternans are still controversial.
METHODS
The study subjects were 89 patients in those the PSVT was documented on 12 leads electrocardiography. The mechanism of PSVT was also proven by electrophysiologic study and radiofrequency catheter ablation. QRS alternans was defined as QRS beat to beat oscillation lasting over 10 seconds at least over 2 ECG leads. We analyzed the incidence of QRS alternans during PSVT and studied correlation with the mechanism of PSVT, cycle length, location of bypass tract, left ventricular mass and left ventricular ejection fraction measured by transthoracic echocardiography.
RESULTS
QRS alternans was present in 12 of 89 patients (l3.6%) and limited only to atrioventricular reentrant tachycardia. The tachycardia cycle length and age were significantly shorter and younger in the group showing QRS alternans (p<0.05, p<0.01 respectively). Accessory pathway site, left ventricular mass, and ejection fraction were not related with the presence of QRS alternans
CONCLUSION
Although there may be various factors related to QRS alternans, we proposed QRS alternans was eletrocardiographic finding related with shorter tachycardia cycle length of PSVT and patient's age.