Introduction: Although focal atrial tachycardia (AT) is known to sometimes be ablated from the noncoronary aortic cusp (NCC), the electro-anatomic characteristics of NCC-AT are not well known.
Methods: We compared the clinical, 12-lead electrocardiogram (ECG), and transthoracic echocardiogram characteristics of 6 women (median age, 66.5 years) with NCC-AT and 12 age-matched women (median age, 64.0 years) with atrioventricular nodal reentrant tachycardia (AVNRT) as the control group.
Results: There was no difference in the prevalence of hypertension between the two groups (67 vs. 33 %, respectively, P = 0.3213). The resting ECG of the NCC-AT group vs. that of the AVNRT group showed a significantly longer PQ interval (170.0 (interquartile range (IQR), 157.5-180.0 ms) vs. 140.0 ms (IQR, 122.5-147.5 ms), P = 0.0010) and leftward shifting of the QRS axis (4° (IQR, -26.0° to 24.0°) vs. 57° (IQR, 43.0-70.2°), P = 0.0087). The upper interventricular septum (IVS) thickness was significantly greater (15.6 (IQR, 11.9-18.7 ms) vs. 11.7 mm (IQR, 10.2-12.9 ms), P = 0.0393), and the angle formed by the aortic roof and IVS (AS angle) was significantly steeper (103.0° (IQR, 94.2-119.2°) vs. 122.5° (IQR, 108.5-128.5°), P = 0.0343) in the NCC-AT group than in the AVNRT group.
Conclusions: Our data suggest that NCC-AT is characterized by a longer atrioventricular (AV) conduction time, steeper AS angle, and thicker IVS than are seen with AVNRT. These electrocardiographic and echocardiographic characteristics from the IVS to the peri-AV nodal regions may have some effect on the development of NCC-AT.