Background: Distinguishing the origin of ventricular tachycardia (VT) by electrocardiogram (ECG) which is performed in all patients, helps to diagnose the cause of VT before trying invasive procedures. The aim of this study was to compare the ECG findings in patients with VT originating from Right or Left Ventricular Outflow Tracts (RVOT or LVOT).
Methods : Fifty nine patients with VT originating from LVOT or RVOT were selected for this cross-sectional study. The patients were recruited while they were attending Shahid Rajaei Hospital in Tehran, Iran in 2009-2010 for catheter ablation. The participants were evaluated for the prevalence of LVOT and RVOT and were compared for the success rate of radiofrequency catheter ablation.
Results : Out of 59 patients, 44.1% were male and 55.9% were female. The mean age of the participants was 41.67 (SD=13.76) years. QRS transition and notch in ECGs were significantly different (respectively, P=0.027 and P=0.007) between patients with LVOT and RVOT. R-to-QRS duration in precordial leads was significantly longer in patients with LVOT than those with RVOT [0.81 (SD=0.06) ms vs. 0.69 (SD=0.16), P=0.015]. Successful ablation was performed in 73.2% of patients with RVOT versus 93.3% of those with LVOT, but despite a higher rate the differences were not statistically significant (P=0.215).
Conclusion: In this study, RF catheter ablation was successful like other studies on patients with ventricular tachycardia and RVOT VT and LVOT VT had significant differences in notch, QRS transition and R-to-QRS duration in precordial leads which are important in differentiating between the two conditions.