Abstract 1038: Role of Electroanatomical Mapping in the Evaluation of Tricuspid Annular Ventricular Tachycardia
Ventricular tachycardia (VT) arising adjacent to the tricuspid annulus (TA) is reported to occur in the absence of structural heart disease (Tada et al, Heart Rhythm 2007, 4:7–16), but is also observed in arrhythmogenic right ventricular dysplasia/cardiomyopathy (ARVD/C). Electroanatomical mapping (EAM) is a useful tool for identifying regions of myocardial scar in this latter group of pts. The presence and distribution of scar in pts diagnosed with idiopathic TA VT is unknown. Group 1 consisted of 10 pts with idiopathic TA VT (mean age 39 ± 13 yrs). Pts with peri-His VT were excluded. Evaluation included 2-D echocardiography, signal-averaged ECG, and magnetic resonance imaging. Other than LBBB VT, no pt had additional Task Force criteria for ARVD/C, though 3 pts had transient precordial T wave inversions of uncertain significance. Group 2 consisted of 10 pts who met Task Force criteria for ARVD/C (mean age 38 ± 12 yrs). All pts were referred for catheter ablation and underwent EAM in sinus rhythm (mean 196 ± 86 sites/pt). Right ventricular (RV) volume and scar area (bipolar voltage ≤ 1.5 mV) were calculated by custom software. TAVT was present in all Group 1 pts, and 8/10 Group 2 pts. ECG characteristics between the two groups were similar, with a LBBB superior axis configuration, precordial transition ≥ V5, and limb lead QRS notching. The location of successful ablation sites around the TA did not differ between groups. RV volumes in Group 2 (208±47 cc, 108±26 cc/m2) were significantly greater than in group 1 (137±35 cc. 66±6 cc/m2, p < 0.05). In group 2, all pts had RV scar identified by EAM which was bounded by the inferior and/or lateral TA in 9/10 pts, with varying degrees of apical extension or outflow tract involvement. The mean scar area was 48.1±23.6 cm2 (18.8±8.6 % of RV endocardial area). In group 1, 5/10 pts had scar adjacent to the TA, usually near the site of VT origin. In these pts, the extent of scar was significantly less than in group 2 (15.7±10.4 cm2, 10.0±5.2% RV endocardial area, p< 0.05). Pts with TAVT but no clinical evidence of ARVD/C frequently have scar identified by EAM. The prognostic implication of this finding is unknown, but close follow-up to detect the development of more overt disease in these pts may be warranted.