Upgrade to biventricular pacing in patients with conventional pacemakers and heart failure: a double-blind, randomized crossover study

Abstract

To investigate whether patients with previously implanted conventional pacemakers and severe heart failure benefit from an upgrade to a biventricular system. Study inclusion criteria were New York Heart Association (NYHA) classes III and IV, dominant paced rhythm, and no left bundle branch block in the pre-pacing ECG. Ten patients with pacemakers (four VVIR due to slow atrial fibrillation and six DDDR, of which four were due to high-degree atrioventricular block and two to sinus node disease) were upgraded to a biventricular pacing (BVP) system. The median duration of pacing before the upgrade was 5.7 years. Assessments of 6-min walk test, symptom score, brain natriuretic peptide (pro-BNP), and echocardiography were made pre-operatively. After a run-in period of 1 month in BVP following the upgrade, the patients were randomized to a 2-month period in either BVP or right ventricular pacing (RVP), followed by 2 months in the other mode, in a double-blind crossover fashion. After each period, the pre-operative measurements were repeated. After study completion, patients were asked to select their preferred period. The median 6-min walking distance was significantly longer in BVP (400 m) vs. RVP (315 m), P = 0.02. The symptom score was also significantly better in BVP (P = 0.005). Median pro-BNP was significantly lower in BVP than in RVP, 3,030 vs. 5,064 ng/L (P = 0.005). Six patients demanded an early crossover in RVP but none in BVP (P = 0.015), and all patients except one expressed a preference for BVP. However, echo parameters did not show any significant differences between BVP and RVP. Pacemaker patients with heart failure and dominant paced heart rhythm benefit substantially from an upgrade to BVP, in terms of physical performance and symptoms. The upgrade resulted in significantly improved cardiac function as reflected by reduced levels of pro-BNP.