Pulmonary Vein Tachycardia: Is the Sinus Rhythm P-wave Useful?

Abstract

Correspondence: Dr P. M. Kistler, The Heart Centre, The Alfred Hospital Commercial Road, Melbourne, Australia 3004 E-mail: peter.kistler@bakeridi.edu.au Focal atrial tachycardia (AT) accounts for up to 15% of patients referred for electrophysiologic study for supraventricular tachycardia SVT.1 Tachycardia foci do not occur randomly throughout the atria but rather cluster at predefined anatomic locations. In the right atrium, the commonest site of origin is at the crista terminalis, with other locations at the tricuspid annulus, coronary sinus ostium, right atrial appendage and peri-nodal region.2-4 The most frequent site of origin in the left atrium is at the pulmonary vein ostia, with the mitral annulus and left atrial appendage less frequent.5-8 Focal AT is often refractory to medical therapy and catheter ablation has become the mainstay of therapy, with high long-term success. Much can be learned about the likely site of origin of the tachycardia from a careful analysis of the tachycardia P-wave.9 The responsible focus can usually be localised to 1 or 2 neighbouring sites, allowing a targeted approach to point mapping. In addition, the distinction between left and right atrial foci is useful in anticipating the requirement for left atrial access. Lead V1 is the most useful in determining the likely site of origin, with a negative or positive-negative biphasic P-wave in V1 highly predictive of a right atrial (RA) focus, whereas a positive or negative-positive morphology in V1 is suggests left atrial (LA) origin. 9,10 The major limitation of P-wave morphology is the inability to identify a P-wave unencumbered by the preceding T-wave and in the setting of structural atrial disease, which is now common following extensive catheterisation for atrial fibrillation (AF). In this issue of Revista Espanola de Cardiologia, Bazan et al report a series of 87 consecutive patients with focal AT undergoing electrophysiologic study using a 3D electroanatomic mapping system.11 Four groups were defined: group 1 (n=25) with pulmonary vein (PV) AT alone; group 2 (n=18) with PV AT and coexistent AF; group 3 (n=7) with other forms of LA AT; and group 4 (n=37) with RA AT. Clinical and electrophysiologic characteristics including the sinus rhythm P-wave morphology were then evaluated across all 4 groups. Groups 1 and 4 (PV AT and RA AT) had significantly less structural heart disease and left atrial dilatation compared with groups 2 and 3. There was a predominance of superior vein foci for PV AT and PV AF and the tachycardia cycle length was shorter compared with non PV sites. The likely tachycardia mechanism was enhanced automaticity or triggered activity in the majority of PV foci (24/25 group 1, 17/18 group 2) compared with reentry in non-PV foci (4/7 group 3, 16/44 group 4) although only limited conclusions can be made regarding tachycardia mechanism from a clinical study. The authors report a higher incidence of sinus rhythm (SR) P-wave notching and a longer SR P-wave duration in left atrial foci compared with right atrial foci. The PV AT group achieved acute success in 24/26 with 2 recurrences of AT and 1 patient with paroxysmal AF (PAF) at 34 (10) months follow-up. The PV-AF group obtained acute success in 17/18 procedures; however, long-term success was limited, with recurrent AT in 4 and recurrent AF in 6.