Sinus Node Dysfunction (SND), part II – SICK SINUS!

6 Dec

Sick sinus syndrome– characterized by

  • chronic, inappropriate sinus bradycardia, which may be symptomatic if there is failure of the “escape” rhythyms
  • sinus pauses, sinus arrest, and sinoatrial block
  • alternating bradycardia and atrial tachyarrhthmias, including atrial fib (tachy-brady syndrome)


The American Journal of Cardiology published a study of 35 patients with symptomatic sick sinus syndrome

  • 45 years of age or older, and had documented mean sinus rate less than 45 bpm and/or intermittent SA block.
  • After a 4 year follow-up (mean 17±15 months)
    • 20 patients (57%) had cardiovascular events that required treatment:
    • 8 had syncope (23%);
    • 6 had overt heart failure (17%);
    • 4 patients had chronic atrial fibrillation (11%);
    • 2 patients had poorly tolerated episodes of paroxysmal tachyarrhythmias (6%).


The bottom line:

Not all patients with sinus node dysfunction need a pacemaker immediately, but if you have a patient with symptomatic sinus pauses (syncope or near syncope) and you are not sure that it is sinus arrhythmia, you cannot safely send the patient home without further evaluation.


Submitted by K. Estes.


References: AHA/ACC guidelines for pacemaker insertion (JACC 2008; 51(21):e1-e62), UpToDate, and Dr. Smith’s ECG blog


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