(Circulation. 1999;100:e143.)
© 1999 American Heart Association, Inc.
Circulation Electronic Pages |
Optimal Pacing Mode for Sick Sinus Syndrome
Professor of Medicine The George Washington University, Washington, DC
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To the Editor:
I read with interest the article on the treatment of patients who have sick sinus syndrome (SSS) with single-chamber atrial pacing by Anderson et al.1 However, their finding of the annual risk of second- or third-degree atrioventricular (AV) block of only 0.6% per year contrasts somewhat with the reported findings that abnormal AV conduction was demonstrated in 57% to 67% of patients with SSS using invasive electrophysiologic techniques.2 3 4 Therefore, although Anderson et al1 demonstrated that abnormalities of AV conduction cause clinical problems only infrequently, it should be clear that a significant number of patients with SSS cannot be treated with atrial pacing alone. In these cases, dual chamber pacing (DDD or DDI, preferably with rate adaptation) should be the treatment of choice because the atrial transport function is then preserved.
The choice should not be restricted to dual-chamber versus single-chamber atrial pacing only. Another viable option in the treatment of SSS in these patients is ventricular pacing, which was first reported in 1968.5 Ordinarily, pacing from a ventricular site would not be expected to affect atrial ectopic activity. However, after successful ventricular capture following transvenous catheter pacing, atrial tachyarrhythmias often no longer recur. Two explanations can be offered. First, the improvement of atrial function through improved coronary circulation secondary to the restoration of an effective regular ventricular rhythm may favorably affect the stimulation and fibrillation threshold of the atria.5 Second, ventricular pacing causes constant retrograde depolarization of the AV node and the atria and, by suppressing the nodal and atrial ectopic pacemakers, not only prevents atrial tachyarrhythmias but also protects against competitive rhythm.5 Ventricular inhibited (VVI) pacing should be the procedure of choice when the dominating atrial rhythm is fibrillation or flutter or when a stable atrial lead position with satisfactory electrophysiologic characteristics cannot be accomplished.
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1. Anderson HR, Nielsen JC, Thomsen PEB, Thuesen L, Vesterlund T, Pedersen AK, Mortensen PT. Atrioventricular conduction during long-term follow-up of patients with sick sinus syndrome. Circulation. 1998;98:1315–1321.
2. Vallin H, Edhag O. Associated conduction disturbances in patients with symptomatic sinus node disease. Acta Med Scand. 1981;210:263–270.[Medline] [Order article via Infotrieve]
3. Cheng TO, Ertem G. Is "sick sinus syndrome" a sickness of sinus node alone? Circulation. 1971;44 (suppl II):II-150.
4.
Narula OS. Atrioventricular conduction
defects in patients with sinus bradycardia: analysis by His
bundle recordings. Circulation. 1971;44:1096–1110.
5. Cheng TO. Transvenous ventricular pacing in the treatment of paroxysmal atrial tachyarrhythmias alternating with sinus bradycardia and standstill. Am J Cardiol. 1968;22:874–879.[Medline] [Order article via Infotrieve]
Response
Department of Cardiology, Skejby Sygehus, Aarhus University Hospital, Aarhus, Denmark
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We thank Dr Cheng for his interest in our article showing that atrioventricular (AV) conduction remains stable during the long-term follow-up of patients with sick sinus syndrome who were treated with single chamber atrial (AAI) pacing.1 We are familiar with the older studies cited by Dr Cheng in which abnormalities in AV conduction can be seen using invasive techniques in a large proportion of patients with sick sinus syndrome. However, none of these abnormalities has been found to predict clinically important AV block in patients with sick sinus syndrome and, as a consequence, routine invasive electrophysiological testing is not recommended anywhere today before pacemaker implantation in these patients. Our results confirm the finding of a 0.6% annual risk of high-grade AV block that was determined in a meta-analysis of 28 studies on AAI pacing in sick sinus syndrome.2 Therefore, the risk of high-grade AV block requiring an upgrade of the AAI pacemaker is <1% per year if patients with sick sinus syndrome are selected carefully by using the following clinical criteria: no grade 2 or 3 AV block, a surface ECG PQ interval
0.22 s in patients 70 years and a PQ interval 0.26 s in patients
>70 years, no bundle branch block, and 1:1 AV conduction during atrial
pacing at 100 bpm.1 3 As long as dual-chamber pacing has
not been proven to be clearly superior to single-chamber
ventricular (VVI) pacing in these patients,4
AAI pacing should be the first treatment choice for patients with sick
sinus syndrome who have normal AV conduction.5 |
References |
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1. Andersen HR, Nielsen JC, Thomsen PE, Thuesen L, Vesterlund T, Pedersen AK, Mortensen PT. Atrioventricular conduction during long-term follow-up of patients with sick sinus syndrome. Circulation. 1998;98:1315–1321.
2. Rosenqvist M, Obel IW. Atrial pacing and the risk for AV block: is there a time for change in attitude? Pacing Clin Electrophysiol. 1989;12:97–101.[Medline] [Order article via Infotrieve]
3. Brandt J, Anderson H, Fahraeus T, Schuller H. Natural history of sinus node disease treated with atrial pacing in 213 patients: implications for selection of stimulation mode. J Am Coll Cardiol. 1992;20:633–639.[Abstract]
4.
Lamas GA, Orav J, Stambler BS, Ellenbogen KA,
Sgarbossa EB, Huang SKS, Marinchak RA, Estes NAM III, Mitchell GF,
Lieberman EH, Mangione CM, Goldman L, for the Pacemaker Selection in
the Elderly Investigators. Quality of life and clinical outcomes in
elderly patients treated with ventricular pacing as
compared with dual-chamber pacing. N Engl J Med. 1998;338:1097–1104.
5. Andersen HR, Nielsen JC, Thomsen PE, Thuesen L, Mortensen PT, Vesterlund T, Pedersen AK. Long-term follow-up of patients from a randomised trial of atrial versus ventricular pacing for sick sinus syndrome. Lancet. 1997;350:1210–1216.[Medline] [Order article via Infotrieve]
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