Interventricular mechanical dyssynchrony determines abnormal heightening of plasma N-terminal probrain natriuretic peptide level in symptomatic bradyarrhythmia patients with chronic dual-chamber vs. single-chamber atrial pacing.

Objective: Debates about adverse effects of ventricular- vs. atrial-based pacing have never ended, especially regarding cardiovascular outcomes in common pacemaker populations.
Methods: To investigate the contribution of right ventricular apical pacing to the left ventricular negative remodeling, we measured the inter- and intraventricular mechanical dyssynchrony by echocardiography as well as plasma N-terminal pro-brain natriuretic peptide (NT-proBNP) level in 116 consecutive patients of symptomatic bradyarrhythmias including sinus node dysfunction (SND) in 80 and atrioventricular block in 36. Dual-chamber rate-modulated pacing (DDDR) pacemakers were implanted in 76 patients (SND, 40), and single-chamber ventricular rate-modulated pacing (AAIR) pacemakers in 40 (all SND). Clinical manifestations were retrospectively correlated.
Results: After 3.5 years of pacing, DDDR pacemaker patients demonstrated higher plasma NT-proBNP concentration (503 +/- 111 pg/ml) than AAIR patients (194 +/- 42 pg/ml, p = 0.002) despite similar cardiovascular function at baseline. Multivariate regression analysis revealed that the only predictor of the highest quartile of plasma NT-proBNP, i.e. >or=386 pg/ml, was the interventricular contraction time difference (p = 0.01). Reprogramming to minimize ventricular pacing percentage in 8 patients of SND caused parallel reduction of plasma NT-proBNP.
Conclusion: Interventricular mechanical dyssynchrony, imposed mostly by right ventricular apical pacing, could lead to abnormal heightening of plasma NT-proBNP concentration after chronic DDDR pacing in common pacemaker patients with normal baseline left ventricular function.
((c) 2007 S. Karger AG, Basel.)