Abstract
Introduction: Inappropriate sinus tachycardia (IST) is a syndrome characterized by unexpectedly fast and prolonged sinus rates at rest or with minimal physical activity. Epidemiologic characteristics are uncertain, but most patients are young and female. When IST occurs in athletes, its management (controlling symptoms and reducing heart rate) can present additional challenges. We designed an observational pilot study to investigate whether a food supplement can be useful in the treatment of IST when standard therapy is refused. Methods: We enrolled 50 consecutive recreational athletes affected by frequent recurrences of IST. Twelve-lead ECG and Holter ECG parameters were recorded at enrollment (T0) and after a 6-month treatment (T1) with the food supplement. Symptoms and quality of life were also evaluated through specific questionnaires. The study population was compared to a historical control group of 25 patients receiving ivabradine as treatment for the same clinical condition. Results: The resting ECG heart rate was 88.7 ± 12.4 bpm (T0) and 73.6 ± 6.6 bpm (T1) (p < 0.00001); Holter average heart rate was 88.4 ± 3.3 bpm and 74.9 ± 4.8 bpm (p < 0.0001). Holter ECG maximum heart rate was 147.1 ± 16.7 bpm and 139.2 ± 16.8 bpm (p = 0.06); Holter minimum heart rate was 49.9 ± 6.5 bpm and 50.5 ± 6.9 bpm (p = 0.33). Finally, the number of sustained episodes decreased from 3.3 ± 1.7 to 0.8 ± 0.8 (p < 0.00001). The following variations in ASTA scores were observed: ASTA symptom scale (range: 0-27) decreased from 14.9 ± 2.1 to 5.8 ± 1.4 (p < 0.00001), while ASTA HR QoL (range: 0-39) decreased from 24.1 ± 2.1 to 10.8 ± 2.3 (p < 0.00001). Conclusions: The findings of our pilot study suggest that this food supplement could play a beneficial role in managing symptoms and improving quality of life in recreational athletes affected by IST who refuse standard medical therapy. These clinical effects appear to correlate with significant improvements in resting ECG parameters and some Holter ECG parameters.