Inappropriate sinus tachycardia is an uncommon clinical condition and often misdiagnosed as emotional and/or mental illnesses. We present a case of 33-year-old lady who is normally fit and well, presented with palpitation for 3 months. Her symptoms occurred at rest or even on mild exertion. She was referred to cardiology clinic for palpitation of unclear cause. Her day time resting heart rate is usually ranging between 110-140 bpm and her heart rate disproportionately increased with minimal exertion. All the blood tests including thyroid function test, phaeochromocytoma screening were normal. CXR and Echo showed normal findings. 24-hour ambulatory ECG monitoring showed predominantly sinus tachycardia which settled nocturnally with mean heart rate of 103 bpm. She was reviewed by cardiologist who made a diagnosis of inappropriate sinus tachycardia and ivabradine 5 mg BD was commenced. Her symptoms significantly improved with ivabradine and she was given further follow up cardiology appointment.

Kyaw Zaya is currently an Internal Medicine Trainee (IMT) from University of Plymouth NHS Trust, UK.  He has successfully completed his MRCP (London) in 2019 and also achieved MBA from University of Northampton, UK.