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Several previous studies have revealed differences in the electrocardiographic characteristics of VAs originating from RCC and LCC. However, the electrocardiographic criterion for distinguishing these arrhythmias is still to be elucidated and the utility of aVL/aVR ratio is unknown.
We studied 23 consecutive patients (mean age 57 ±15 years, 7 male) who underwent successful catheter ablation for idiopathic VAs originated from LCC (n=17) and RCC (n=6). QRS waveform, duration and amplitude from standard 12-lead ECG were measured.
All patients with RCC VAs presented with R morphology in lead I, whereas for patients with LCC VAs, 4 presented with QS morphology, 11 with RS or rs morphology and 2 with R morphology (x2=15.22, P<0.01). The QRS duration in lead I was significant shorter in patients with LCC VAs than in patients with RCC VAs (82±32 ms vs. 121±12 ms, P<0.05). The R wave amplitude in lead III, aVF and the Q wave amplitude in aVL were significantly higher in patients with LCC VAs compared to patients with RCC VAs (2.10± 0.54 mv vs. 1.35± 0.36 mv, P<0.01; 2.06±0.44 mv vs. 1.52±0.36 mv, P<0.05; 1.23±0.31 mv vs. 0.61±0.21 mv, P<0.01). Compared to patients with RCC VAs, III/II ratio and aVL/aVR ratio were significant higher in patients with LCC VAs (1.09±0.12 vs. 0.80±0.11; 1.29±0.38 vs. 0.61±0.22, all P<0.001). The ability of aVL/aVR ratio to distigush LCC VAs was assessed by using an ROC curve. The area under the curve for the ROC curve of aVL/aVR ratio was 0.951 [95% confidential interval 0.862-1.000]. An aVL/aVR ratio of more than 1.00 had 77% sensitivity and 100% specificity for detecting patients with LCC VAs.
A relatively large R wave in lead I is seen in RCC VAs. Patients with LCC VAs showed higher R wave in lead III, aVF and deeper Q wave in aVL than patients with RCC VAs. The ratio of aVL/aVR >1.00 is a simple and reliable index in distinguishing VAs from LCC and RCC.