4 min readUpdated: Sep 29, 2026 04:41 PM IST
He was 23 when his smartwatch showed something unusual: his heart rate was around 120 beats per minute. There was no obvious reason for it. He was not exercising and wasn’t sick. It could have been easy to dismiss the number as a device error or a temporary change. Instead, he decided to get it checked and came to the hospital.
A closer look brought out another detail. For around three-and-a-half months, he had been having episodes of palpitations, along with moments when he felt as though he might faint. The symptoms had not initially seemed connected to the smartwatch reading. Further evaluation found that he had atrioventricular nodal re-entry tachycardia (AVNRT), a type of abnormal heart rhythm that can cause the heart to suddenly beat very fast.
Doctors performed a test called an electrophysiology study to find out where the abnormal heartbeat was coming from. They then treated the problem with a procedure called radiofrequency ablation. In this procedure, doctors identify the tiny area of the heart that is causing the faulty electrical signal, use a catheter guided through a blood vessel to deliver controlled heat to the affected area and stop the irregular heartbeats. The patient remained stable after the procedure and was discharged with advice to return for follow-up care.
“This is a reminder that heart-related problems do not always begin with chest pain or a dramatic symptom. Sometimes, the first clue may be a change in something as basic as the heart rate, particularly when it occurs along with symptoms that may otherwise be easy to overlook,” says Dr Varun Bansal, senior consultant, cardiothoracic and vascular surgery, Indraprastha Apollo Hospitals, New Delhi.
When is a heart rate of 120 a concern?
Heart rate is not a fixed number. It goes up during exercise, when a person is anxious or stressed, and with fever or dehydration. Caffeine and some medicines can also cause a temporary increase.
The situation is different when the heart rate remains high while a person is resting, particularly when there is no clear reason for it.
A fast heartbeat may be felt as pounding, racing or fluttering in the chest. Some people may also experience dizziness, breathlessness, weakness, chest discomfort or even fainting. Others may have very few symptoms, particularly between episodes, as was the case with this young man.
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A single high reading does not establish that something is wrong with the heart. It is the persistence of the change, the circumstances in which it occurs and any accompanying symptoms that provide more useful information. Recognising these changes early and consulting a specialist when needed can help identify an underlying rhythm problem in time and allow appropriate treatment before it leads to further complications.
Why age does not always tell the whole story
Heart health is often discussed in relation to older adults. High blood pressure, diabetes, high cholesterol, smoking and family history are well-known cardiovascular risk factors.
But a young age does not mean that an unusual heart rhythm or persistent change in heart rate can automatically be ignored. Rhythm disorders such as AVNRT can also occur in younger people and may present with episodes of a rapid or pounding heartbeat.
This is where awareness becomes important. A person does not need to panic every time a wearable device shows a number outside their usual range. But a reading that is repeatedly unusual, particularly at rest or when accompanied by palpitations, dizziness or near-fainting, is worth discussing with a doctor.
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What can a smartwatch tell you?
Wearable devices have made it easier for people to notice changes in heart rate. They can record readings during the day and may alert a person when the heart rate is unusually high or low. But the number on the screen is only a starting point. Smartwatches are not designed to replace a medical examination and cannot, by themselves, explain why the heart rate has changed. The reading can also be affected by movement, the way the watch is worn and other factors.
