Vol 71, No 7 (2013)
Original articles
Published online: 2013-07-17

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Differentiation of arrhythmia originating from the right or left ventricular outflow tract based on the QRS morphology of premature ventricular beats and duration of repolarisation

Krzysztof Szydło, Anna Maria Wnuk-Wojnar, Maria Trusz-Gluza, Andrzej Hoffmann, Seweryn Nowak, Iwona Woźniak-Skowerska, Jarosław Kolasa, Jarosław Chmurawa, Beata Nowak-Jeż, Anika Doruchowska
Kardiol Pol 2013;71(7):723-729.

Abstract

Background: Premature ventricular beats (PVBs) and monomorphic ventricular tachycardia originating from the right ventricular
outflow tract (RVOT) are the most frequent forms of idiopathic ventricular arrhythmias, but arrhythmia originating from the
left ventricular outflow tract (LVOT) may be found in about 10% of these patients.

Aim: To compare electrocardiographic (ECG) patterns and duration of repolarisation after PVBs originating from the left and
right superior part of the interventricular septum which were successfully treated with radiofrequency catheter ablation.

Methods: We studied 62 patients who did not receive antiarrhythmic drug treatment before ablation, including 50 patients
with RVOT arrhythmia (21 males, mean age 42 ± 14 years, left ventricular ejection fraction [LVEF] 61 ± 6%) and 12 patients
with LVOT arrhythmia (3 males, mean age 41 ± 17 years, LVEF 59 ± 9%). Pre-ablation 24-h Holter ECG recordings were
analysed for the total number of PVBs. In addition, we evaluated ectopic beat QRS duration, prematurity index and duration
of repolarisation (QT interval, JT interval and TpeakTend values uncorrected for the heart rate) based on ten random daytime
PVBs during a period of stable sinus rhythm at a rate of 60–70 bpm.

Results: The study groups did not differ by age, LVEF, heart rate and the number of PVBs. RVOT arrhythmia was characterised
by a lower prematurity index (0.59 ± 0.11 vs. 0.72 ± 0.09, p = 0.001) and a lower R/S ratio in leads V1–V3 (p < 0.01 for
each lead). QRS duration of right-sided PVBs was shorter compared to that of left-sided PVBs (147 ± 13 vs. 166 ± 13 ms,
p = 0.002), QT and JT intervals were similar (QT: 422 ± 32 vs. 429 ± 27 ms, p = 0.35; JT: 272 ± 27 vs. 266 ± 27 ms,
p = 0.31), and TpeakTend was shorter in RVOT arrhythmia (100 ± 10 vs. 110 ± 6 ms, p = 0.01). Combination of R > S in
lead V3 and TpeakTend-PVB > 110 ms identified LVOT arrhythmia with a sensitivity of 75% and specificity of 96%.

Conclusions: Ventricular arrhythmias originating from the left or right superior part of the interventricular septum are not
only characterised by different ECG patterns of ventricular ectopic beats but also show significant differences in the repolarisation
phase.

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Polish Heart Journal (Kardiologia Polska)