Percentage Of Ventricular Pacing In Patients With Atrioventricular Block After Pacemaker Implantation

BackgroundAtrioventricular (AV) block is defined as a delay or interruption in the transmission of an impulse from the atria to the ventricles due to an anatomical or functional impairment in the conduction system. Most patients with complete (third degree) AV block and symptomatic second degree AV block have an indication for pacemaker placement. In order to maintain physiologic pacing, dual chamber pacing is recommended. However, clinical studies showed long-term right ventricular pacing (RVP) reduced left ventricular function and adverse cardiac remodeling, as well as increased incidence of heart failure, atrial fibrillation and death. It is very important to take some therapeutic strategies for minimizing unnecessary RVP.ObjectiveTo investigate the percentage of ventricular pacing (%VP) in atrioventricular block and analyze the risk factors which may affect %VP, with the aim of providing guidance for electrophysiologists when programming pacemaker.MethodsA total of 228 consecutive patients with atrioventricular block indicated for pacemaker implantation were enrolled in Peking Union Medical College Hospital between January 2006 and September 2014. Clinical characteristics and programming data were analyzed.ResultsThere were 125 males and 103 females. The mean age was 68.21±14.45 years. The median time of follow-up was 24 months. One hundred and seventy-eight patients (79.5%) were pacing dependent (%VP>70%). Patients with complete AV block were more likely to be pacing dependent compared to the patients with second degree AV block (85.0% vs 69.3%, P<0.01). Patients with persistent AV block were more likely to be pacing dependent compared to the patients with paroxysmal AV block (84.1% vs 62.5%, P<0.001). Older patients (≥65y) were more likely to be pacing dependent compared to younger patients (<65y) (81.9% vs 69.9%, P<0.05). Patients with hypertension were more likely to be pacing dependent compared to the patients with normotension (83.0% vs 70.1%, P<0.05). Patients without heart failure were more likely to be pacing dependent compared to the patients with heart failure(81.1% vs 55.6%, P<0.01). Patients with dual chamber pacing were more likely to be pacing dependent compared to patients with single chamber pacing (80.4% vs 58.3%, P<0.05). Sex, course of disease, coronary heart disease, hyperlipidemia, diabetes, beta-blockers, calcium channel blockers, ACE inhibitors and angiotensin receptor blockers seemed to be no significant relationship with %VP. Twelve of 96 patients (12.5%) with persistent complete AV block were not pacing dependent, and 70 of 101 patients (69.3%) with second degree AV block were pacing dependent.ConclusionsOlder patients with dual chamber pacing, persistent and complete AV block as well as without heart failure were more likely to be pacing dependent. The AV node function seems to partly recover in some patients with complete AV block, while some patients with second degree AV block will progress to complete AV block, which will provide guidance for electrophysiologists when programming pacemaker on AV search algorithm.