ASSESSMENT OF LEFT-VENTRICULAR FUNCTION AFTER RADIOFREQUENCY AND DIRECT-CURRENT ATRIOVENTRICULAR NODE ABLATION

Background: There is limited information available regarding the effec t of catheter ablation of the antioventricular (AV) junction on left v entricular (LV) function. Both deterioration and improvement in LV fun ction have been reported following direct current (DC) ablation of the AV junction. The deterioration of LV function following DC ablation o f the AV junction maybe due to the accompanying barotrauma, DC arcing and direct coagulation, or even the effects of chronic ventricular pac ing. If this deterioration of LV function was a result of the accompan ying effects of DC shock, the use of radiofrequency ablation (RF) shou ld not result in deterioration of LV function. Aim: To study LV functi on before and after different methods of AV junction ablation and in p atients with chronic ventricular pacing without AV junction ablation. Material: This study assessed LV function in patients following RI; ab lation, low energy DC ablation of the AV junction and compared the res ults with our previously reported finding in patients who had AV junct ion ablation using high energy DC shock. A group of patients undergoin g permanent single chamber ventricular pacemaker implantation without AV junction ablation were selected as controls. Methods: All patients were paced in the ventricle at 110 beats/minute during LV function ass essment by radionuclide angiography. Global LV function and segmental wall motion abnormalities were assessed before, immediately following and three months after ablation. Results: In the high energy DC ablati on group, a fall in global LV function (50 +/- 3.0% to 43 +/- 3.0%, p = 0.02) and impairment of segmental wall motion were detected. Low ene rgy DC ablation resulted in segmental wall motion impairment similar t o high energy DC but without affecting global ejection fraction (47.0% +/- 6.7 to 45.5% +/- 3.1, p > 0.05). Neither RF ablation (44.0% +/- 3 .3 to 45.3% +/- 3.5, p > 0.05), nor chronic pacing (46.7% +/- 4.9 to 4 7.0% +/- 2.9 p > 0.05) had any effect on global or segmental LV functi on. Conclusions: Low energy DC or RF ablation of the AV junction does not affect global LV ejection fraction. The deterioration of global LV function after high energy DC shock ablation appears to be related to the accompanying effects of DC energy and not to the effects of chron ic ventricular pacing.