Hello and thank you for using HCM.I carefully read your question and I understand your concern.You shoud not worry .I'll try to explain you something and give you my opinion.
Normal heart beats range between 50-100 beat for minute in normal conditions. During a physical or emotional
stress heart beats can rise over 100 and this is quite normal.
When the heart beats in a regular rhythm over 100 beat for minute we call this
sinus tachycardia.
It gives strong heart beats,palpitations, difficulty in breathing deeply,
anxiety sensation.
There are different reasons that might lead to this excessive
heart rate.The first thinks to mention for young person are emotional stress, excessive coffee consumption, energy drinks.
There are also different pathologys like anamia,
hyperthyroidism or other cardiac anomalies that might be responsible for this heart rate.
So, as this has been a problem for your partner, if I was the treating doctor I will recommend some examination like an electrocardiogram, a cardiac echo to evaluate heart function and structure, a full blood analyze to exclude
anemia and thyroid gland problems. And the most important one holter rhythm monitoring for 48 h.This means monitoring heart rhythm for two days to evaluate the heart frequency during day and nighy.
Only after this we can better judge what we are dealling whith and how to manage it.
It might just be a streesed period and it will soon pass.
Hope I was helpful.Wish your partner good health.
Best regards.