Usefulness of Bifocal Pacing in Patients with Heart Failure and Intraventricular Conduction Delay

BACKGROUND: Bifocal pacing (BFP) has been proposed as a feasible alternative to cardiac resynchronization therapy. AIM: To evaluate BFP in patients with severe heart failure and significant intraventricular conduction delay and to compare it with biventricular pacing (BVP). METHODS: Echocardiographic examination including TDI and invasive measurement of haemodynamics was performed under basal conditions, during BFP and during BVP. RESULTS: Fifty patients were included: 29 with ischaemic heart disease (IHD), 21 with idiopathic dilated cardiomyopathy (IDCM). LV dp/dt(max) increased during BFP compared to the basal state (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), but not in IHD patients. Interventricular mechanical delay (IVMD) decreased in BFP (43+/-22 ms vs. 53+/-31 ms, p=0.006), but BVP produced even shorter IVMD (22+/-19 ms, p<0.0001). In all patients, 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). CONCLUSIONS: BFP improves LV haemodynamics 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.