Bradycardia
A resting heart rate below 60 beats per minute in an adult.
What it means
Bradycardia is a resting heart rate below 60 beats per minute. From the Greek bradys, slow.
It is a normal finding in several circumstances. Trained endurance athletes commonly have resting rates in the forties, reflecting an efficient heart rather than a diseased one, and heart rate falls physiologically during sleep.
Pathological causes include disease of the heart's conducting system, an underactive thyroid, raised intracranial pressure, and medication — particularly beta blockers such as propranolol, rate-limiting calcium channel blockers and digoxin.
In practice
Recorded in routine observations and characterised on an electrocardiogram, which identifies whether conduction through the heart is delayed or blocked.
"Heart block" describes specific patterns of conduction failure and is graded first to third degree by severity.
Why it matters
The distinction that matters is whether the slow rate is producing symptoms. An asymptomatic athlete with a rate of 48 requires nothing; the same rate causing dizziness, fatigue, breathlessness or blackouts does.
Bradycardia with fainting, near-fainting or chest pain requires urgent assessment, since complete heart block may require a pacemaker. Where medication is responsible, dose adjustment often resolves it.
Clinically reviewed by Dr Mohammad Zubair Khan, GMC 7563469
Last reviewed
August 30, 2026