Objectives: Right ventricular (RV) pacing induces a left bundle branch block
pattern on ECG and may promote heart failure. Patients with dual chamber
pacemakers (DCPs) who present with progressive reduction in left ventricular
ejection fraction (LVEF) secondary to RV pacing are candidates for cardiac
resynchronization therapy (CRT). This study analyzes whether upgrading DCP to
CRT with the additional implantation of a left ventricular (LV) lead improves
LV function in patients with reduced LVEF following DCP implantation. Methods:
Twenty-two patients (13 males) implanted with DCPs and a high RV pacing
percentage (>90%) were evaluated in term of new-onset heart failure symptoms.
The patients were enrolled in this retrospective single-center study after
obvious causes for a reduced LVEF were excluded with echocardiography and
coronary angiography. In all patients, DCPs were then upgraded to
biventricular devices. LVEF was analyzed with a two-sided t-test. QRS duration
and brain natriuretic peptide (BNP) levels were analyzed with the unpaired
t-test. Results: LVEF declined after DCP implantation from 54±10% to 31±7%,
and the mean QRS duration was 161±20 ms during RV pacing. NT-pro BNP levels
were elevated (3365±11436 pmol/L). After upgrading to a biventricular device,
a biventricular pacing percentage of 98.1±2% was achieved. QRS duration
decreased to 108±16 ms and 106±20 ms after 1 and 6 months, respectively. There
was a significant increase in LVEF to 38±8% and 41±11% and a decrease in NT-
pro BNP levels to 3088±2326 pmol/L and 1860±1838 pmol/L at 1 and 6 months,
respectively. Conclusion: Upgrading to CRT may be beneficial in patients with
DCPs and heart failure induced by a high RV pacing percentage. (Anatol J
Cardiol 2016; 16: 678-83