Left ventricular pacing in neonates and infants with isolated congenital complete or advanced atrioventricular block: short- and medium-term outcome

Aims Right ventricular (RV) pacing may induce left ventricular (LV) dysfunction: neonates and infants with isolated congenital complete/advanced atrioventricular block (CCAVB) are at high risk of developing RV pacing-induced LV dyssynchrony, remodelling, and dysfunction. We prospectively investigated whether LV pacing results in normal LV function and good clinical status in the short/medium term. Methods and results In this single-centre, prospective study, 10 consecutive patients with CCAVB (median age 4 months, range: 0.1-16) underwent pacemaker implantation (4 VVIR, 6 DDD) using epicardial leads (on the LV apex in 8, on the LV free wall in 2). Data were collected at implantation and at 1- and 12-month follow-up. Echocardiographic evaluation included two-dimensional/three-dimensional assessment of LV dimensions, function (ejection fraction, EF), and ventricular synchrony (interventricular and intraventricular dyssynchrony). Prior to pacemaker implantation, EF was normal in six patients, 50% in two, <= 40% in two. All patients showed good clinical status and normal LV dimensions at follow-up. Patients with LV dilatation and impaired EF at implantation showed LV reverse remodelling and enhanced LV function. Normal LV function and synchrony were observed in most patients (one patient with EF 53% and three patients with mild dyssynchrony at 12-month follow-up). Paced QRS complex tended to be wider than native QRS complexes (P = 0.07); QTc duration of paced complexes was within normal limits or only slightly prolonged, without significant differences compared with QTc interval of native complexes. Conclusion At short-and medium-term follow-up, LV pacing results in satisfactory LV electromechanical function and synchrony in neonates and infants with CCAVB.