• Interventional Techniques & Devices
• Cardiology
• Arrhythmias
• Cardiology Clinical Trials

• Interventional Techniques & Devices
• Cardiology & Cardiovascular Medicine
• Arrhythmias
• Cardiology Clinical Trials

Patients with high-grade atrioventricular (AV) block and preserved baseline left ventricular (LV) function who need a high percentage of right ventricular (RV) pacing show small but significant reductions in LV ejection fraction (LVEF) over a 2-year period from pacing with either RV apex (RVA) or RV high septum (RVHS), with no difference between RVA and RVHS.

Gerry Kaye, MD, Department of Cardiology, University of Queensland, Princess Alexandra Hospital, Brisbane, Australia, presented results of the Protection of Left Ventricular Function During Right Ventricular Pacing [PROTECT-PACE; NCT00461734], a randomized, prospective, international, multicenter, single-blinded trial to compare the effect of pacing the RVA versus the RVHS on LV systolic function in patients with high-grade AV block. Full results of the study will be published in the European Heart Journal.

Sponsored by Medtronic UK, the study was undertaken to test the hypothesis that RVHS pacing is superior to RVA pacing in preventing LV dysfunction in patients with preserved LVEFs who need ventricular pacing. The need to examine pacing other than with the RVA is highlighted by accumulating evidence that RVA pacing has multiple deleterious effects, including the potential to result in long-term LV dysfunction.

The study included 240 patients with high-grade AV block and sinus rhythm or permanent atrial fibrillation (AF) who were randomly assigned to RVA pacing (n=120) or RVHS pacing (n=120). Patients with selected cardiac diseases were excluded, along with those with indications for implantable cardioverter-defibrillators or cardiac resynchronization therapy and those with intermittent AV block or reversible causes for AV block, those with known paroxysmal AF prior to enrollment, and those who needed amiodarone therapy within 6 months prior to study enrollment. Table 1 shows demographics of all patients enrolled in the study.

The primary end point of the study was change in LVEF measured by transthoracic echocardiography from baseline to 24 months. Secondary end points included AF and atrial tachyarrhythmia burden, change in brain-type natriuretic peptide level, change in 6-minute walk distance, lead implantation duration and fluoroscopy time, and death and heart failure hospitalization.

At 2-year follow-up, 85 patients in the RVA group and 83 patients in the RVHS group were available for assessment. Both groups showed small but significant changes in LVEF at 2 years from baseline, with no difference in the primary outcome between the 2 treatments (Table 2).

Table 3 shows the results of secondary outcomes. No differences were seen between the 2 treatment groups except for lead implantation duration and fluoroscopy time, both of which were significantly longer for RVHS pacing.

On the basis of these results, the trial suggests that RVHS pacing is not protective of LV function compared with RVA pacing in patients with preserved baseline LV systolic function, according to Dr. Kaye. Left unanswered is whether RV pacing itself is the problem, whether there is some specific site within the RV where pacing may be protective of LV function, or whether preventing LV dysfunction with RV pacing is patient specific and therapy needs to be individualized.

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