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Background Localization of atrioventricular accessory pathways (AP) from Electrocardiogram (ECG) is crucial for successful ablation. We analyzed the value of limb lead 2 versus 3 QRS vector discordance on surface ECG among right‐sided pathways. Methods Data from consecutive patients undergoing successful ablation of manifest AP were analyzed. They were categorized into two groups—Gr I: Endocardial ablation from anterior and anterolateral tricuspid annulus (TA, 10−1 o'clock, right anterolateral [RAL]); Gr II: Ablation outside this region (1−10 o'clock of TA). Inferior lead discordance (ILD) was defined as positive QRS complex (monophasic R, Rs) in lead 2 with negative/equiphasic QRS vector in lead 3 (rS, S, RS). Maximally pre‐excited ECGs during electrophysiology study were compared for presence of ILD. Result Among total 22 cases (Age 36 ± 18 years, 12 males), ILD was noted in 4/4 cases of Gr I. It was absent among 17/18 cases of right‐sided AP in Gr II. The only case in Gr II having ILD was ablated near 8 o'clock (posterolateral). In contrast to the other four cases, aVF was negative, along with lead 3. A close differential was mid‐septal AP (MSAP). However, the MSAP had absence of r in V1 and lead 2 having rS/RS complex in contrast to strongly positive QRS in RAL pathways. The sensitivity and specificity of ILD for RAL are 100% and 95%, respectively. The positive, negative predictive value, and accuracy are 80%, 100%, and 95%, respectively. Conclusion Positive QRS complex in lead 2 with negative QRS in lead 3 in maximally pre‐excited ECG is often predictive of anterior and anterolateral location among right‐sided pathways.

A 65‐year‐old gentleman underwent dual chamber pacemaker implantation (DDDR, St Jude Medical) 7 years back for infra‐hisian complete heart block. He was completely asymptomatic and came for his annual routine check‐up. After undergoing ECG with and without magnet, he was prepared for device evaluation. After placing the programmer wand over the chest as soon as the “;interrogate” button on the programmer screen was pressed, the patient immediately experienced pre‐syncope but recovered instantly as the wand was promptly withdrawn. After taking him to the casualty room with all resuscitation measures in hand, a repeat attempt of interrogation was made after connecting ECG, which revealed reproducible loss of capture (LOC), exclusively during wand placement. A differential diagnosis of lead failure, battery depletion, or wand related issues were considered. However, serial ECGs recorded without wand raised the possibility of AutoCapture malfunction. With all precautions, the device was programmed to fixed ventricular output mode after which interrogation could be performed safely. There was a remaining battery longevity of 2 years with acceptable lead parameters and stable threshold. He continues to be asymptomatic at 10 months of follow up.

In selective patients with low-intermediate SYNTAX score and without diabetes and LV dysfunction, ULMCA PCI with DES is feasible.

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