Heart rate 46 on an adult - what does it mean?

Where 46 bpm sits on the adult scale

What a resting pulse of 46 means

Endurance training makes the heart muscle stronger, so it moves more blood per beat and needs fewer beats at rest. Runners, cyclists and swimmers commonly rest between 40 and 60 bpm. During sleep, almost everyone's heart rate drops 10–20 bpm below the daytime resting value.

If you are not particularly fit, possible causes include medications (beta blockers and other heart-rate-lowering drugs), an underactive thyroid (hypothyroidism), sleep apnea and conduction problems of the heart. These are easy to check with an ECG and a blood test, or a sleep study for sleep apnea.

Ranges apply to adults and children aged 10 and older, measured at rest (American Heart Association). By the numbers: at 46 bpm the heart beats about every 1.30 seconds — roughly 66,240 beats a day.

A pulse of 46 in someone over 65

Older adults usually have resting heart rates very similar to younger people. Age lowers the maximum rate the heart can reach during effort, but it barely moves the resting value. So when a 70- or 80-year-old who has never been an endurance athlete measures 46, ageing alone is not a satisfying explanation. It points toward the heart’s electrical wiring, a medicine, or both.

The heartbeat starts in the sinus node, a small cluster of pacemaker cells in the right atrium. The signal then passes through the AV node to the ventricles. Over decades, both areas can lose cells and gain scar-like fibrous tissue. The sinus node may fire more slowly or pause, and the AV node may let fewer signals through. Doctors call the first pattern sick sinus syndrome and the second heart block. Both become more common with age.

Clues that the slow rate matters

In older people the symptoms of a slow heart can be subtle and easy to blame on age. Signs worth reporting include:

• falls or near-falls without tripping, especially soon after standing
• new confusion, memory slips or drowsiness during the day
• getting tired after short walks that used to be easy
• a pulse that does not rise much when climbing stairs or carrying shopping

That last point has a name, chronotropic incompetence: the heart cannot speed up enough to meet demand. A resting 46 that rises well with effort is less concerning than one that stays flat.

Medicines are a frequent contributor at this age, because many older adults take several at once. Beta blockers, some calcium channel blockers, digoxin, amiodarone and donepezil, a drug for dementia, can all slow the pulse, and their effects can stack.

Bringing 46 to the doctor

Book an appointment in the coming days and take the full medicine list, including eye drops and supplements. An ECG is the first step and can show whether the beat starts normally and how the signal travels. If the problem comes and goes, a longer recording over a day or more may follow. Blood tests for thyroid function and potassium are often added.

If the slow rate turns out to be the cause of symptoms and no medicine is to blame, a pacemaker is a common, well-established treatment. Fainting, chest pain or sudden breathlessness with a rate this low warrants a call to 911. Background on how resting values compare across adults is on the normal adult heart rate page.

For a reliable resting value, sit quietly for five minutes first and average a few mornings: Resting Heart Rate: What It Says About Your Health. You can also measure by tapping along on the start page.

Nearby values

• 41 bpm
• 42 bpm
• 43 bpm
• 44 bpm
• 45 bpm
• 47 bpm
• 48 bpm
• 49 bpm
• 50 bpm
• 51 bpm

Measured on a child instead? See heart rate 46 in a child.

Sources: American Heart Association: All About Heart Rate · MedlinePlus: Pulse · ACSM position stand on exercise intensity (2011)

This page explains a single reading in general terms. It is not a diagnosis. Heart rate alone cannot tell whether the rhythm is regular or whether the heart is healthy — if you are worried, talk to a doctor.