Single versus dual chamber pacing in the young: Noninvasive comparative evaluation of cardiac function

The advantages of atrial synchrony over asynchronous ventricular pacing remain unclear in the young, chronically right ventricular (RV) - paced patient. This is in contrast to the older patient with inherent diastolic dysfunction who has been shown to benefit from atrial synchrony with dual chamber (DDD,R/VDD), over single chamber rate response (VVI,R) ventricular pacing. The goal of this study was to noninvasively assess cardiac function in a group of young, RV-paced patients before and after establishment of atrial synchrony. Echocardiographic data were retrospectively analyzed from 10 patients with congenital or acquired complete AV block, who were VVI,R paced for 10.2 ± 2 years (mean age at study 19.2 ± 8.9 years), and were subsequently converted to DDD,R/VDD pacing (mean age at study 20.7 ± 9.5 years). Paired t-test analysis of left ventricular (LV) systolic and diastolic function during VVI, R versus DDD,R/VDD pacing did not result in any short-term difference in LV short axis fractional area of change or FAC (53% ± 7.5% vs 56.8% ± 8.7%) or mitral maximal velocity (E) normalized to mitral flow velocity time integral (VTI) (5.2/s ± 1.5 vs 4.4/s ± 1.5). A decrease in mitral flow E/A ratio was observed after short term DDD,R/VDD pacing (2.2 ± 0.5 vs 1.9 ± 0.3). Atrial synchronous dual chamber pacing in young patients with complete AV block does not lead to any appreciable early change in global LV function over single-site RV pacing. Therefore, early establishment of atrial synchrony in the young asymptomatic VVI,R-paced patient with normal intrinsic ventricular function may not be warranted.