Why does my heart suddenly race out of nowhere?
Few sensations are as unsettling as feeling your heart suddenly pound or race for no clear reason. It can happen while you are resting or in the middle of an ordinary task, and the suddenness of it often causes understandable alarm. In the great majority of cases, a racing heart is harmless and settles on its own within a short time. Occasionally, though, a racing heart that begins suddenly and keeps returning is a sign of an abnormal heart rhythm, which a heart rhythm specialist can diagnose and, in many cases, treat successfully.
What is happening when your heart races
The sensation of becoming aware of your own heartbeat, which may feel like a strong pounding or a fast, fluttering beat in the chest, is known as a palpitation. Palpitations are common, usually last a few seconds or minutes, and are often felt in the chest or neck, as the NHS explains. Much of the time they reflect a normal heart responding to something, rather than a fault in the heart itself.
A racing heart becomes more relevant when it starts abruptly for no obvious reason, keeps returning, or comes with other symptoms. This kind of pattern can indicate that the heart's electrical system, which sets the timing of each beat, is producing abnormal signals rather than working normally.
The everyday causes
Plenty of ordinary things speed the heart up, and these are usually nothing to worry about. A surge of adrenaline from stress or a sudden fright is the most common, and the effect can linger for a while after the moment has passed. Caffeine and alcohol are frequent triggers, and so are nicotine and dehydration, or a bout of illness with a fever. Some cold and flu remedies and asthma inhalers can do the same, and hormonal changes around the menopause are a recognised trigger too.
Palpitations from these causes tend to be short-lived and to settle once the trigger passes, which is why the NHS suggests cutting back on things like caffeine and alcohol where they seem to bring symptoms on. This is a sensible first step, and often the only one needed.
When a racing heart is a rhythm problem
Supraventricular tachycardia, or SVT, tends to start and stop suddenly, like a switch being flicked, and produces a very fast but regular heartbeat. Atrial fibrillation, by contrast, produces a fast and irregular heartbeat, and it is the most common heart rhythm disorder. Extra or skipped beats, known as ectopic beats, are very common and usually harmless, though they can feel alarming. Each of these behaves differently, and telling them apart is the first job of an assessment.
When to get it checked
The NHS advises anyone to book an appointment with a GP or a cardiologist if the palpitations keep happening, last for a long time, are getting worse, or simply are concerning. A racing heart that follows a clear pattern, or that arrives with breathlessness or dizziness, is worth having properly investigated rather than left unchecked.
A few situations, though, do need urgent care. Call 999 if a racing heart comes with chest pain or severe breathlessness, or if you faint or feel about to pass out, as the British Heart Foundation advises, as these can be signs of something serious.
How a specialist finds the cause
The single most useful thing is to record your heart rhythm while it is racing, as this is what shows exactly what is going on. A standard ECG in clinic captures the rhythm at that moment, but a sudden racing often passes before you reach a doctor. For that reason, a portable monitor worn for anywhere from a day to a week or two, or a small recorder for longer periods, may be needed so that an episode is caught as it happens. Recordings from a smartwatch or a personal ECG device can also help point the assessment in the right direction.
Once the rhythm has been recorded during an episode, the cause is usually clear, and the benefit of capturing it is that many of these rhythm problems respond well to treatment. Some, including SVT and several other fast rhythms, can be corrected at their source with a keyhole procedure called catheter ablation, which provides a lasting cure for many patients.
Speak to Dr Eysenck
If your heart races unexpectedly and the episodes keep returning, recording the rhythm and identifying the cause is the most reliable way to resolve it. Get in touch to arrange a consultation with Dr Eysenck at one of his clinics across London and Kent.
Frequently asked questions
Is a sudden racing heart always dangerous?
No, and most of the time it is harmless, particularly when it is brief and clearly linked to a trigger such as stress or caffeine. The value of an assessment is that a specialist can identify the less common rhythm causes and treat them, and can reassure you when the cause turns out to be harmless.
Can anxiety make my heart race like this?
Yes, anxiety and a rush of adrenaline are among the most common reasons for a racing heart. A fast heart rhythm problem can feel very similar to anxiety, and the two are easily mistaken for one another, so a sudden racing heart that keeps returning is worth having checked rather than assuming it is caused by stress.
Do I need a GP referral to see Dr Eysenck?
Dr Eysenck welcomes self-referring patients as well as referrals from GPs and hospital doctors. If you have a referral letter, it is helpful to bring it, along with any recordings from a smartwatch or monitor.