The acute and chronic effects of different right ventricular site pacing on left ventricular mechanical synchrony as assessed by phase analysis of SPECT myocardial perfusion imaging.

BACKGROUND

This study aimed to assess acute and chronic effects of right ventricular mid-septum (RVS) versus right ventricular apex (RVA) pacing on left ventricular (LV) mechanical dyssynchrony using phase analysis of gated single photon emission computed tomography myocardial perfusion imaging (MPI).

METHODS

Thirty-nine patients with complete atrioventricular (AV) block, who were indicated for permanent pacing, were recruited and randomized to receive RVA (n = 20) or RVS (n = 19) pacing. All patients underwent MPI at 1 week and 6 months after pacemaker implantation. LV dyssynchrony and cardiac function were assessed by MPI and compared between the two groups.

RESULTS

There were no significant differences in baseline characteristics between the RVS and RVA groups. The paced QRS duration was significantly longer in the RVA group than in the RVS group. LV dyssynchrony parameters were not significantly different between the groups at the 1-week follow-up, but they were significantly smaller in the RVS group than in the RVA group at the 6-month follow-up. LV dyssynchrony parameters significantly decreased in the RVS group from the 1-week follow-up to the 6-month follow-up, but were unchanged in the RVA group. No differences in LV function parameters were observed between the groups at the 1-week and 6-month follow-ups.

CONCLUSIONS

RVS pacing produces better electrical and mechanical synchrony than RVA pacing for patients with complete AV block.