Carlo Pappone, Giuseppe Oreto*,
Adriano Salvati, Francesco Lullo, Filippo Gullotta, Stefano Bianchi, Patrizio Mazzone,
Maria Luisa Loricchio, Francesco Furlanello, Sergio Chierchia.
Cardiology Department, S. Raffaele Hospital, Milan,
*Department of Medicine and Cardiology, University of Messina, Messina, Italy
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Inappropriate sinus tachycardia is a relatively rare
arrhythmia characterized by excessive resting heart rate and/or disproportionate sinus
rate increase as a consequence of mild effort. More than one mechanism may account for
IST, including enhanced sinus node automaticity, ß-adrenergic hyperactivity, and reduced
vagal drive to the sinus node. In this sense IST may be regarded as the common
manifestation of different disorders, namely as a "syndrome" rather than as a
single disease. The clinical diagnosis is easy on the basis of standard ECG, Holter
monitoring and effort test. Secondary causes of sinus tachycardia must be ruled out before
diagnosing IST. Prognosis of patients with IST is poorly known; treatment should be
undertaken only for symptomatic relief. Betablockers or verapamil are suitable for the
treatment of IST; in patients unresponsive to drugs, catheter ablation of the sinus node
should be recommended. Although the experience with catheter ablation in patients with IST
is limited, this technique appears as very promising, clearly preferable to ablation of
the A-V junction or surgical isolation of the right atrium.
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