The aim of this study is to prospectively compare the effectiveness and safety of ivabradine and beta-blockers in the treatment of inappropriate sinus tachycardia.

Inappropriate sinus tachycardia (IST) is a non-paroxysmal arrhythmia, characterized by a persistently high sinus heart rate (HR) and/or an exaggerated HR response to minimal exertion, and can be responsible for palpitations, asthenia, chest pain, dizziness and syncope, which can be highly invalidating. Conventional treatment of IST, targeted to symptoms control, mainly consists on β-blockers. However, these drugs are often insufficient or not well tolerated because of side effects (mostly hypotension) that usually limit the administered dose. Ivabradine, a sinus rate lowering agent currently employed in Europe in the treatment of stable angina and chronic heart failure, has recently been demonstrated to be effective and safe in the treatment of IST by a few case reports and clinical trials. A randomized clinical trial comparing ivabradine to β-blockers has not be performed yet.

Inclusion Criteria:

• Inappropriate sinus tachycardia (HR >100 bpm at rest ECG and/or medium Holter ECG HR >90 bpm)
• Age > 18 years;

Exclusion Criteria:

• Secondary causes of sinus tachycardia;
• Structural heart diseases,
• Postural orthostatic tachycardia syndrome;
• Sinus nodal reentrant tachycardia;
• Contraindications to beta-blockers;
• Administration of beta-blockers, non-di-hydropiridinic calcium channels antagonists, class I and III anti-arrhythmic drugs or digitalis at the time of enrollment;
• Age < 18 years;
• Inability of giving informed consent;