CE-542-01 PRECORDIAL ‘REVERSE PATTERN BREAK’: A NOVEL PREDICTOR FOR EPICARDIAL POSTEROSEPTAL ACCESSORY PATHWAYS

Abstract

Posteroseptal (PS,also known as inferior paraseptal) accessory pathways(AP) may occasionally lie within the coronary sinus (CS), its tributaries, in a CS diverticulum (CSD) or along the epicardial surface. We encountered precordial reverse pattern break (RPB) of QRS morphology in some patients with epicardial APs and analysed all ECGs of posteroseptal accessory pathway(PSAP) cases. Inclusion criteria:Consecutive patients aged> 18 years, who underwent successful RF ablation in the PS region. Exclusion criteria- Failed ablation,Ablation at the left sided endocardium,Ablation deep inside the main CS, beyond 3 cm of the CS ostium (left free wall epicardial pathways). The cases were divided into two groups: Group En: Endocardial ablation; Group Ep: Ablation within the CS/CSD/epicardial surface. Definition:RPB is defined as monophasic tall R in V2 larger than V1 and V3 along with either (i) R/S < 1 in V3, or (ii) S wave in V3 > 4 mV. Among 66 cases [Age: 32±12 year, 40 males], 53 were ablated endocardially and 13 cases epicardially (12 inside a CS diverticulum, one in epicardium after gaining pericardial access).The baseline characteristics were comparable.RPB was present in 10/13 of Group Ep, but only in 6/53 cases of Group En.The sensitivity and specificity of RPB for epicardial location were 63% and 94% respectively, while the positive predictive value(PPV) was 77 %. The negative predictive value (NPV) was 89% and the accuracy was 87%. Among the patients who underwent ablation for PS accessory pathways,RPB was more often observed on the preexcited ECGs in patients having epicardial APs. This pattern may indicate the need for mapping within the CS/CSD or or epicardium.