title: Ivabradine in combination with metoprolol succinate in the treatment of inappropriate sinus tachycardia.
abstract: BACKGROUND
  Inappropriate sinus tachycardia (IST) is a clinical syndrome characterized by excessive resting heart rate (HR) or a disproportional increase in HR during exercise. β-blocker or calcium channel-blocker therapy is often noneffective or not well tolerated. The HR reduction on ivabradine is similar to β-blockers but in some patients its efficacy to resolve all IST-related symptoms is limited. The aim of the study was to assess the efficacy and safety of combining ivabradine with metoprolol succinate in patients with refractory highly symptomatic IST.
  
  
  METHODS
  Twenty patients (36 ± 10 years; 16 women) with IST were enrolled. All patients received metoprolol succinate 95 mg single dose during the first month of the study. After 4 weeks of treatment with metoprolol, ivabradine was administered as adjuvant therapy up to 7.5 mg twice daily. Holter monitoring and treadmill stress test were performed at baseline, after 4, and 8 weeks of the study, respectively.
  
  
  RESULTS
  We observed significant and similar reduction in resting HR both for metoprolol and for combined therapy compared to the baseline. The mean HR during daily activity was significantly lower on ivabradine and metoprolol compared to monotherapy with β-blocker. The combined treatment yielded a significant increase in exercise capacity as assessed by treadmill stress test. After 4 weeks of combined therapy a significant reduction in IST-related symptoms, measured by means of the European Heart Rhythm Association score, was observed.
  
  
  CONCLUSIONS
  Combining ivabradine with metoprolol is an effective and well-tolerated treatment option for IST in patients with refractory to monotherapy.
authors: Department of Electrocardiology, Medical University, Lodz, Poland. pawel_ptaszynski@wp.pl
authors: Pawel
authors: P
authors: Ptaszynski
authors: Krzysztof
authors: K
authors: Kaczmarek
authors: Jan
authors: J
authors: Ruta
authors: Thomas
authors: T
authors: Klingenheben
authors: Iwona
authors: I
authors: Cygankiewicz
authors: Jerzy K
authors: JK
authors: Wranicz
mesh_terms: D000319:Adrenergic beta-Antagonists / Q000009:adverse effects / Q000627:therapeutic use*; D000328:Adult; D001552:Benzazepines / Q000009:adverse effects / Q000627:therapeutic use*; D004351:Drug Resistance; D004359:Drug Therapy, Combination; D015716:Electrocardiography, Ambulatory / Q000187:drug effects; D005080:Exercise Test / Q000187:drug effects; D005260:Female; D006801:Humans; D000077550:Ivabradine; D008297:Male; D008790:Metoprolol / Q000009:adverse effects / Q000031:analogs & derivatives* / Q000627:therapeutic use; D008875:Middle Aged; D013616:Tachycardia, Sinus / Q000188:drug therapy*; D016896:Treatment Outcome
chemical_list: D000319:Adrenergic beta-Antagonists; D001552:Benzazepines; D000077550:Ivabradine; D008790:Metoprolol
keywords: heart rate; inappropriate sinus tachycardia; ivabradine; metoprolol