Idiopathic intramural LVOT VAs exhibited a maximum deflection index (0.49±0.05) that was midrange between aortomitral continuity (0.45±0.06) and LV summit VAs (0.52±0.07).
Observational (n=82)
What are the electrocardiographic and electrophysiological characteristics of idiopathic intramural LVOT VAs compared to endocardial and epicardial LVOT VAs?
Intramural LVOT VAs have distinct electrocardiographic and electrophysiological characteristics that are intermediate between endocardial and epicardial origins, which may aid in their localization prior to ablation.
BACKGROUNDS: Idiopathic ventricular arrhythmias (VAs) originating from the left ventricular outflow tract (LVOT) sometimes require catheter ablation from both the endocardial and epicardial sides for their elimination, suggesting the presence of intramural VA foci. This study investigated the prevalence and electrocardiographic and electrophysiological characteristics of these idiopathic intramural LVOT VAs when compared with the idiopathic endocardial and epicardial LVOT VAs. METHODS AND RESULTS: We studied 82 consecutive VAs with origins in the aortomitral continuity (n=30), LV summit (n=34), and intramural site (n=18). The maximum deflection index (the time to the maximum deflection in the precordial leads/QRS duration) was the largest in LV summit VAs (0.52±0.07), smallest in aortomitral continuity VAs (0.45±0.06), and midrange in intramural VAs (0.49±0.05). The electrocardiographic and electrophysiological characteristics of the intramural LVOT VAs were similar to those of the aortomitral continuity VAs. The intramural LVOT VAs exhibited a significantly smaller R-wave amplitude ratio in leads III to II, and ratio of the Q-wave amplitude in leads aVL to aVR, and a significantly earlier and later local ventricular activation time relative to the QRS onset at the His bundle and successful ablation sites than the LV summit VAs, respectively. CONCLUSIONS: Intramural sites account for a significant proportion of LVOT VAs. The electrocardiographic and electrophysiological characteristics of the idiopathic intramural LVOT VAs were midrange between those of the idiopathic endocardial and epicardial LVOT VAs, and more similar to those of the idiopathic endocardial LVOT VAs than those of the idiopathic epicardial LVOT VAs.
Yamada et al. (Thu,) conducted a observational in Idiopathic ventricular arrhythmias originating from the left ventricular outflow tract (n=82). Intramural LVOT VAs vs. Endocardial (aortomitral continuity) and epicardial (LV summit) LVOT VAs was evaluated on Maximum deflection index. Idiopathic intramural LVOT VAs exhibited a maximum deflection index (0.49±0.05) that was midrange between aortomitral continuity (0.45±0.06) and LV summit VAs (0.52±0.07).