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AAI(R) or DDD(R) – Which Pacing Mode is Right for Patients with Sick Sinus Syndrome?

Abbott Cardiac Rhythm Management | December 16, 2024

While managing patients with sick sinus syndrome (SSS) and normal atrioventricular (AV) conduction, clinicians often find themselves weighing two primary pacing options: AAI and DDD modes. This debate has persisted for years, with experts offering varying recommendations based on evolving clinical evidence. Historically, the British Pacing and Electrophysiology Group advocated for single chamber atrial pacing as the preferred option for these patients.¹ However, more recent guidelines, such as those from the European Society of Cardiology (ESC), suggest dual chamber pacing as the go-to choice for sinus node disease.²

So, what drove this shift? Much of it stemmed from the DANPACE trial, which compared AAI(R) with DDD(R) pacing in SSS patients.³ While the trial found no difference in all-cause mortality between the two modes, it did reveal a 1.7% annual risk of AV block development.³ This has led many physicians to favor DDD pacing, as it potentially reduces the need for future pacemaker reoperation in the event of an AV block.

Why Consider AAI Mode for SSS Patients?

Despite the guidelines AAI pacing remains a relevant option, and there are good reasons to continue the conversation. Several studies have highlighted that AAI pacing is associated with lower rates of atrial fibrillation (AF), stroke, and AV block compared to other pacing modes.^4-7  Moreover, patients with SSS and intact AV conduction may experience better outcomes with AAI pacing, particularly when it comes to long-term risk of AF and heart failure.^3,7-9

One major concern surrounding AAI pacing is the potential development of high-degree AV block and the chances of associated reoperation. However, some researchers believe that this risk may be overstated. Data from several studies show that the likelihood of AV block in SSS patients ranges from 0.6% and 1.8% per year, which is relatively low. ^3,7-9 These results align with the outcomes of the DANPACE trial where the need to switch pacing modes was required in only 9.3% of the AAI patients with a mean of 1.7% per year. Based on the above findings, it might be beneficial to consider single chamber atrial pacing for SSS patients with no AV block.

The rise of leadless pacemakers mitigates several of the complications associated with traditional pacemakers, such as transvenous lead issues and the risks related to the cutaneous pocket. Additionally, devices that offer single chamber leadless atrial pacing, such as the AVEIR™ AR Atrial Leadless Pacemaker, can eliminate the potential adverse effects associated with ventricular over pacing particularly in SSS patients and might be a suitable option for treating SSS patients with no AV block.

Summary

While the debate between AAI and DDD pacing modes for patients with SSS persists, the choice ultimately depends on the individual patient’s condition and the long-term risks associated with each mode. AAI pacing offers benefits like reducing AF, stroke, and heart failure, but concerns about AV block still influence many physicians to choose DDD pacing. The rise of leadless pacemakers presents a promising future for pacing, but further studies are needed to solidify their place in treating SSS.

For information on AVEIR™ AR Atrial Leadless Pacemakers and to access the latest data, please visit our AVEIR AR Atrial Leadless Pacemaker page and explore our leadless pacing solutions.

References:

1. British Pacing and Electrophysiology Group. Recommendations for pacemaker prescription for symptomatic bradycardia. Br Heart J. 1991;66:185–91. https://doi.org/10.1136/hrt.66.2.185
2. McDonagh TA, Metra M, Adamo M, et al. 2021 ESC Guidelines for the diagnosis and treatment of acute and chronic heart failure: Developed by the Task Force for the diagnosis and treatment of acute and chronic heart failure of the European Society of Cardiology (ESC) With the special contribution of the Heart Failure Association (HFA) of the ESC. European Heart Journal. 2021;42(36):3599-3726. doi: 10.1093/eurheartj/ehab368.
3. Nielsen JC, Thomsen PEB, Hojberg S, et al. A comparison of single-lead atrial pacing with dual-chamber pacing in sick sinus syndrome. European Heart Journal. 2011;32(6):686-696. doi: 10.1093/eurheartj/ehr022.
4. Kim WH, Joung B, Shim J, et al. Long-term outcome of single-chamber atrial pacing compared with dual-chamber pacing in patients with sinus-node dysfunction and intact atrioventricular node conduction. Yonsei Medical Journal. 2010;51(6):832-837. doi: 10.3349/ymj.2010.51.6.832.
5. Fored C, Granath F, Gadler F, et al. Atrial vs. dual-chamber cardiac pacing in sinus node disease: a register-based cohort study. Europace. 2008;10(7):825-831. https://doi.org/10.1093/europace/eun118
6. Healey JS, Toff WD, Lamas GA, et al. Cardiovascular outcomes with atrial-based pacing compared with ventricular pacing: meta-analysis of randomized trials, using individual patient data. Circulation. 2006;114(1):11-17. doi: 10.1161/CIRCULATIONAHA.105.610303.
7. Masumoto H, Ueda Y, Kato R, et al. Long-term clinical performance of AAI pacing in patients with sick sinus syndrome: a comparison with dual-chamber pacing. Europace. 2004;6(5):444-450. doi: 10.1016/j.eupc.2004.05.003.
8. Andersen HR, Nielsen JC, Thomsen PE, et al. Atrioventricular conduction during long-term follow-up of patients with sick sinus syndrome. Circulation. 1998 Sep 29;98(13):1315-21. doi: 10.1161/01.cir.98.13.1315.
9. Kristensen L, Nielsen JC, Pedersen AK, et al. AV block and changes in pacing mode during long-term follow-up of 399 consecutive patients with sick sinus syndrome treated with an AAI/AAIR pacemaker. Pacing Clin Electrophysiol. 2001 Mar;24(3):358-65. doi: 10.1046/j.1460-9592.2001.00358.x.