The effects of radiofrequency ablation on left atrial systolic function in patients with atrioventricular nodal reentrant and atrioventricular reentrant tachycardias.

BACKGROUND: Recurrent supraventricular arrhythmias may cause remodelling of the atria. The effects of radiofrequency (RF) ablation of these arrhythmias on left atrial function have not been well established.

AIM: To evaluate the effects of RF ablation on left atrial systolic function in patients with atrioventricular nodal reentrant tachycardia (AVNRT) and atrioventricular tachycardia (AVRT).

METHODS: The study group consisted of 70 patients (22 men), in whom successful RF ablation of slow pathway (35 patients) or accessory pathway (35 patients) was performed. Patients with atrial fibrillation, structural heart disease, ventricular arrhythmias (> class 3 Lown), impaired left ventricular systolic function or on antiarrhythmics were excluded. All the patients had echocardiographic study before and 6 months after ablation. Left atrial systolic function was assessed using atrial ejection force (AEF) according to Manning's formula (AEF = 0.5 x ρ x MA x A(2), r: blood density = 1.06 g/cm(3), MA: mitral orifice area [cm(2)], A: A wave velocity). The following left atrial dimensions were assessed: antero-posterior (LA-AP), infero-superior (LA-IS, long axis), medio-lateral (LA-ML, short axis). The correlations between AEF and electrophysiological parameters were analysed (VA - ventriculo-atrial conduction, VA/CL - tachycardia cycle length).

RESULTS: The AEF increased significantly in the AVNRT group (7.78 vs 10.75 kdynes; p < 0.001) whereas it did not change in the AVRT group (8.96 vs 9.50, NS). Left atrial dimensions decreased significantly in both groups (AVNRT group: LA-AP: 38 vs 34 mm; LA-ML: 37 vs 33 mm; LA-IS: 51 vs 45 mm; p < 0.001; AVRT group: LA-AP: 38 vs 36 mm; p < 0.01; LA-ML: 37 vs 35 mm, p < 0.001; LA-IS: 50 vs 46 mm; p < 0.001). There was a significant correlation between the increment of AEF and electrophysiological parameters of the tachycardia (VA, r = -0.51 and VA/CL, r = -0.53).

CONCLUSIONS: 1. RF ablation of AVNRT is associated with the improvement of left atrial systolic function. 2. Left atrial size decreases following RF ablation of both AVNRT and AVRT. 3. The effects of RF ablation on the left atrial systolic function depends on electrophysiological parameters of the tachycardia (VA and VA/CL).