Utility of distinctive local electrogram pattern and aortographic anatomical position in catheter manipulation at coronary cusps.

Background: The coronary cusps have recently become target sites for radiofrequency catheter ablation of both outflow tract ventricular arrhythmias originating near the coronary cusps (CC-VA) and atrial tachyarrhythmias such as focal atrial tachycardia originating near the noncoronary cusp (NCC-AT). However, the relation between local electrograms recorded at each CC during sinus rhythm and their anatomical position as assessed by aortography has not yet been systematically described.

Results: In 28 patients undergoing RFCA for CC-VA or NCC-AT, amplitudes of the atrial and ventricular potentials at the CCs were measured during sinus rhythm, and the atrial/ventricular (A/V) potential ratio was computed. Relative positions of the CCs were assessed by aortography in 2 X-ray projections. In the right (RCC) and left coronary cusps (LCC), amplitudes of the ventricular potential were larger than those of the atrial potential, leading to an A/V ratio <1 in all patients (0.08 ± 0.10, 0.32 ± 0.21, respectively). In contrast, in the NCC, the amplitude of the atrial potential was larger than the ventricular potential, leading to a higher A/V ratio relative to the CCs (5.7 ± 2.6, P < 0.0001). Aortography demonstrated the rightward and anterior location of the RCC, the leftward and superior location of the LCC, and the inferior and posterior location of the NCC.

Conclusions: Awareness of the distinctive local electrogram pattern of each CC and their positions on aortography should lead to safer and more effective catheter ablation at the CCs.