Left ventricular function and right ventricular pacing for isolated congenital heart block

Abstract

BACKGROUND: Right ventricular pacing has been the treatment of choice in patients with congenital complete atrioventricular block (CAVB). However, the effect of chronic right ventricular pacing on left ventricular function in young patients is still controversial. AIM: The aim of the study was to assess the change in left ventricular systolic function in young patients (age ≤20 years) paced for isolated CAVB and to identify possible predictors of left ventricular systolic dysfunction. METHODS: We studied 55 young patients who underwent permanent right ventricular pacemaker implantation for CAVB in the absence of significant structural heart disease. We excluded patients affected by any condition known to affect left ventricular function. Echocardiographic data prior to and after pacemaker implantation were obtained. RESULTS: The mean age at the time of pacemaker implantation was 20 months, range 2.3-72 months. The mean duration of follow-up was 94.86 (range: 2-268 months). Chronic right ventricular pacing affected left ventricular shortening fraction (LVSF) significantly (pre = 37.8 ± 7.8 vs. post = 32.8 ± 5.5%, P = 0.0036). In 14 patients (25.4%), LVSF decreased by at least 7% (group A). The only parameter studied able to significantly discriminate the two groups was a better baseline LVSF in group A (baseline LVSF: 42.1 ± 5.2 vs. 32.2 ± 2.2%, P = 0.019; cut-off value >39%, P <0.0001; area under the curve = 0.887). CONCLUSION: Chronic right ventricular pacing in young patients without significant structural heart disease is responsible for a significant reduction in left ventricular systolic function, especially in patients with a good baseline LVSF. These patients need close follow-up not only for pacing parameters but also for left ventricular functional evaluation.