Bifocal pacing - A novel cardiac resynchronization therapy? Results of bifocal pacing study and review of the current literature.

BACKGROUND Bifocal pacing (BFP) has been proposed as a more feasible alternative of cardiac resynchronization therapy (CRT). AIM To evaluate BFP in patients with severe congestive heart failure and significant intraventricular conduction delay and to compare it with biventricular pacing (BVP). METHODS Both echocardiographic examination including tissue Doppler imaging and invasive measurements of cardiac hemodynamics was performed under basal conditions and during BFP and BVP. RESULTS 50 patients were included: 29 patients with ischemic heart disease (IHD), 21 patients with idiopathic dilated cardiomyopathy (IDCM). Left ventricular (LV) pressure gradient (dp/dt max) increased during BFP compared to the baseline (13.4 %, 95 % CI 9.2-17.6 %, p < 0.0001) and a further increase was achieved during BVP (29.5 %, 95 % CI 23.7-35.4 %, p < 0.0001). A significant correlation was found between the distance of the right ventricular apical and outflow tract leads and percentage of dp/dt max increase in IDCM patients (r = 0.72, p < 0.001), but not in IHD patients. Interventricular mechanical delay (IVMD) decreased in BFP compared to baseline (43 +/- 22 ms vs. 53 +/- 31 ms, p = 0.006). BVP produced even shorter IVMD (22 +/- 19 ms, p < 0.0001). In all patients, the regional systolic contraction times were significantly shortened, corresponding with prolongation of the respective regional diastolic filling times during both BFP (p < 0.05 for all segments) and BVP (p < 0.001 for all segments). The effect of BVP on regional systole shortening was more pronounced. CONCLUSIONS BFP improves LV hemodynamics by decreasing the inter- and intraventricular conduction delays. The leads in the right ventricle should be placed at the longest achievable distance. BVP is superior to BFP.