Right ventricular apex versus right ventricular outflow tract pacing: prospective, randomised, long-term clinical and echocardiographic evaluation.

INTRODUCTION: In patients treated with permanent pacing, the electrode is typically placed in the right ventricular apex (RVA). Published data indicate that such electrode placement leads to an unfavourable ventricular depolarization pattern, while right ventricular outflow tract (RVOT) pacing seems to be more physiological.

AIM: To compare long-term effects of RVOT versus RVA pacing on clinical status, left ventricular (LV) function, and the degree of atrioventricular valve regurgitation.

METHODS: Patients with indications for permanent pacing, admitted to hospital between 1996 and 1997, were randomised to receive RVA or RVOT pacing. In 2004 during a final control visit in 27 patients clinical status, echocardiographic parameters and QRS complex duration as well as NT-proBNP level were measured. Analysed parameters were compared between groups and in the case of data available during the perioperative period also their evolution in time was assessed.

RESULTS: Out of 27 patients 14 were randomised to the RVA group and 13 to the RVOT group. No significant differences between groups were observed before the procedure with respect to age, gender, comorbidities or echocardiographic parameters. Mean duration of pacing did not differ significantly between the groups (89+/-9 months in RVA group vs 93+/-6 months in RVOT group, NS). In the RVA group significant LV ejection fraction decrease was observed (from 56+/-11% to 47+/-8%, p <0.05); in the RVOT group LV ejection fraction did not change (54+/-7% and 53+/-9%; NS). Progression of tricuspid valve regurgitation was also observed in the RVA group but not in the RVOT group. During the final visit NT-proBNP level was significantly higher in the RVA group: 1034+/-852 pg/ml vs 429+/-430 pg/ml (p <0.05).

CONCLUSIONS: In patients with normal LV function permanent RVA pacing leads to LV systolic and diastolic function deterioration. RVOT pacing can reduce the unfavourable effect and can slow down cardiac remodelling caused by permanent RV pacing. Clinical and echocardiographic benefits observed in the RVOT group after 7 years of pacing are reflected by lower NT-proBNP levels in this group of patients.