Evolution of paced QRS and QTc intervals in children with epicardial pacing leads.
Permanent ventricular pacing in children is associated with ventricular dysfunction due to asynchronous activation. It is unclear whether paced QRS intervals increase disproportionately over time, which could potentially cause ventricular dysfunction. A total of 52 children, with bipolar steroideluting epicardial leads implanted at a median age of 5.6 years (0.0-17.4), was analyzed and followed up to 12.2 years (median 3.7). Patients were subdivided in two groups: right (RV, n = 21) and left (LV, n = 31) ventricular pacing. To correct for age, standard deviation scores (Z-scores) for paced QRS and QTc intervals were calculated from published standard-ECG norm-values. As a measure for individual paced QRS and QTc interval changes, a regression slope coefficient (incline(i)) was calculated for each patient's course. Mean Z-scores for paced QRS intervals at first and last follow-up were 4.7 +/- 1.2 and 4.9 +/- 0.9 for group RV, 4.4 +/- 1.1 and 4.8 +/- 1.1 for group LV. Incline(i) of paced QRS (group RV: 0.038 [-0.27-0.12], group LV: 0.147 [-0.05-0.30]; p = 0.07) and QTc intervals (group RV: 0.026 [-0.08-0.06], group LV: 0.023 [-0.04-0.09]; p = 0.63) did not differ between both groups and indicated limited interval changes over time. Neither epicardial pacing of the right nor left ventricle caused disproportionate paced QRS or QTc interval increases over time. An age-related prolongation of the electrical activation unlikely causes ventricular dysfunction.