Inadequate, Inappropriate Sinus-Node Tachycardia: An Old Cardiac Arrhythmia In A New Perspective (Ii.) Our Experiences With The Pharmacological Treatment

Objective: The aim of this study was to describe our experiences with pharmacological therapy of patients with inappropriate sinus tachycardia syndrome.Methods: Between 2008 and 2018, 104 patients (92 women, 12 men, mean age: 31 10 years) were treated with this cardiac arrhythmia entity. All patients underwent 12-lead ECG, 24-hour Holter-ECG monitoring and standard bicycle dynamic exercise tests before and after drug treatment (bisoprolol: 5 mg bid; ivabradine: 5 mg bid). Changes in the quality of life were estimated by using the European Heart Rhythm Association (EHRA) score.Results: Both drugs decreased significantly the resting heart rate (control: 102 +/- 10/min; bisoprolol 78 +/- 6/min (p<0.0001), ivabradine: 74 +/- 8/min (p<0.0001). The results of the parameters of the 24-hour Holter ECG recordings (expressed as minimal-maximal [average] heart rate/min) with drug therapy showed a significant decrease from control values in all three parameters: control 58 +/- 8-159 +/- 14 (94 +/- 6)/min; bisoprolol 53 +/- 7-132 +/- 13 (77 +/- 9)/ min (all three: p<0.0001); ivabradine: 51 +/- 6-134 +/- 18 (77 +/- 8)/min (all three: p<0.0001). The sinus rate reduced significantly both before the bicycle dynamic exercise tests (control: 99 +/- 13/min; bisoprolol: 81 +/- 11/min [p<0.0001]; ivabradine: 84 +/- 10/min [p<0.0001]) and at the peaks of the exercise test (control: 164 +/- 15/min; bisoprolol: 140 +/- 16/min [p<0.0001]; ivabradine 142 +/- 14/min [p<0.0001]). The heart rate reducing effects of the two drugs did not differ significantly. The EHRA quality of life score was equally improved by the two drugs (control: 2.3 +/- 0.7; bisoprolol: 1.4 +/- 1.4 [p<0.0001]; ivabradine: 1.1 +/- 0.2 [p<0.0001]). No cardiovascular side effects were observed while taking bisoprolol or ivabradine.Conclusions: Based on our clinical results, it can be pointed out that in the drug therapy of patients with inappropriate sinus node tachycardia: (1) bisoprolol (5 mg bid) and ivabradine (5 mg bid) proved to be equally effective and safe; (2) the heart rate reducing effect of the two drugs - given in the same dosage - did not differ considerably; (3) the pharmacological therapy significantly decreased not only the sinus frequency, but also reduced the symptoms of the patients.