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Which Type of Pacing for High-Grade AV Block in Elders?
New data challenge the conventional choice, but there’s more to consider.
For high-grade atrioventricular (AV) block, most cardiologists choose dual-chamber over single-chamber pacing. However, evidence to support this choice is lacking, particularly in elderly patients. Now, in a randomized trial conducted at 46 centers in Britain, 2021 patients (age 
70; 57% men) with high-grade AV block received dual-chamber or single-chamber pacing. Single-chamber patients were further randomized to fixed-rate or rate-adaptive pacing; in the dual-chamber group, investigators determined programming. Patients with chronic atrial fibrillation or limited life expectancy were excluded from the study. Minimum follow-up was 3 years (median, 4.6).
The two main groups had similar rates of death (about 7% per year); atrial fibrillation (about 3% at 3 years); stroke, TIA, or thromboembolism (about 2% at 3 years); and incident heart failure (about 3% per year). Procedural complications were significantly more common with dual-chamber than with single-chamber pacing (7.8% vs. 3.5%). The type of single-chamber pacing did not affect the overall findings.
Comment: These data challenge the well-established belief that dual-chamber ("physiologic") pacing is superior to single-chamber pacing for elders with high-grade AV block. Is this the end of dual-chamber pacing for such patients (given procedural complications, high cost, and lack of benefit)? An accompanying editorial urges us to withhold judgment on this question. It notes that the present study did not examine quality of life, which dual-chamber pacing has been shown to improve within individual patients. At the end of the day, this study should encourage individualized therapy. For example, dual-chamber pacing might be appropriate for a very active elderly patient with high-grade AV block, but single-chamber pacing would be reasonable for many other elders with this condition.
— Hugh Calkins, MD
Published in Journal Watch Cardiology September 2, 2005
Citation(s):
Toff WD et al. Single-chamber versus dual-chamber pacing for high-grade atrioventricular block. N Engl J Med 2005 Jul 14; 353:145-55.
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- Medline abstract (Free)
Ellenbogen KA and Wood MA. Pacemaker selection — The changing definition of physiologic pacing. N Engl J Med 2005 Jul 14; 353:202-4.
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- Medline abstract (Free)