Abstract 11500: J-Point Syndromes From the Vectorcardiogram Point of View

Abstract

Introduction: The potentially fatal outcome related to J-point syndromes raises heated debate about the pathophysiology of Brugada syndrome (BrS) and early repolarization (ER). It has not been established yet if they carry a depolarization, a repolarization or both electrical problems. Hypothesis: The objective of this study was to define BrS and ER characteristic and distinctive electrical patterns, using aspects of the QRS complex loops, ST-segments and T-waves obtained from the classical vectorcardiogram (VCG). Methods: VCG loops of 29 BrS patients and 30 individuals with ER were analyzed qualitatively and quantitatively. Non-paired t-test and ROC curve statistics were used (p≤ 0.05 significance level). Results: Mean age: 47±15 vs 38±14y.o. (p=0.02), 66% vs 90% male (p=0.03); QRS duration: 102±10 vs 95±13ms (p=0.03), BrS vs ER, respectively. All QRS loops showed an end-conduction delay located in right posterior-anterior quadrant (BrS) or left posterior-anterior quadrant (ER). A “break” in the QRS loop end, very much resembling a “nose”, is seen in BrS (100%), while in ER the QRS loop “break” was smoother with a “fish-hook” shape (100%). Normal T-wave loops with counterclockwise rotation were present in 86.2% of BrS and 73.3% of ER. End-conduction delay of 34±6ms vs 22±5ms (p<0.0001); J-point amplitude of 0.14±0.07mV vs 0.22±0.08mV (p<0.0001); SÂJ-point of 103±19° vs 55±16° (p<0.0001), BrS vs ER, respectively. A 75o cutoff value (ROC analysis) could diagnose BrS (96.6% sensitivity, 93.3% specificity). Conclusions: The vectorcardiogram could clearly differentiate BrS from ER qualitatively as well as quantitatively: the transverse plane of VCG shows in BrS cases a longer end-conduction delay (>30ms), with a right-sided and posterior-anteriorly oriented loop, with the aspect of a “nose”; in ER cases the end-conduction delay is shorter, located at the left posterior-anterior quadrant, with the aspect of a “fish-hook”. With a J-point angle above 75o we could diagnose BrS with 96.6% sensitivity and 93.3% specificity.