DDDR pacing results in left ventricular asynchrony with preservation of ejection fraction and NT-proBNP: a prospective study in sick sinus syndrome and normal ventricular function.

Desynchronization induced by right ventricular pacing may increase the risk for heart failure. We aimed to compare left ventricular (LV) function, synchrony and left atrial size along with NT-proBNP levels, in 2 different modes of pacing: AAIR versus DDDR. This was a prospective study of 60 patients with sick sinus syndrome, preserved LV function and normal atrioventricular conduction. Each pacing mode lasted at least 2 months, in every patient, after which period every patient was switched to the alternate pacing mode. Intraventricular asychrony was assessed by: 1) M-Mode septal-to-posterior wall motion delay (SPWMD), and 2) Tissue Doppler imaging (TDI) septal to lateral delay. NT-proBNP was measured at the end of each pacing mode. LV ejection fraction and left atrial diameter were not different in the 2 pacing modes, although asynchrony was induced in the DDDR arm (p<0.001 for TDI). NT-proBNP was lower in the DDDR compared to the AAIR mode (p=0.003, F=9.64). The NT-proBNP was inversely correlated to LV ejection fraction in the DDDR mode (p=0.0001, R=-0.75), whilst it was significantly correlated to the TDI septal-lateral delay and SPWMD (p=0.007, R=0.4 and p=0.002, R=0.5) in the AAIR mode. In conclusion in sick sinus syndrome with preserved LV function the DDDR mode does not compromise LV systolic function although it causes asynchrony. The NT-proBNP is lower when the right ventricle is paced, is inversely related to LV function and it is related to the degree of LV synchronization in the AAIR mode.