Sir Alex is said to receive regular check-ups and often visits the hospital after training wearing his Manchester United tracksuit.
His treatment involves being sedated or given a general anaesthetic. Two pads are then attached to the torso and a shock is passed through them to restore the heart rhythm, sometimes resulting in burn marks.
A long line of football bosses have suffered from the stress of management.
Six months ago West Ham boss Glenn Roeder was rushed to hospital with a brain tumour. In 2001 Liverpool boss Gerard Houllier needed open-heart surgery. Blackburn Rovers manager Graeme Souness had a bypass in 1992.
Peterborough manager Barry Fry and Wimbledon boss Joe Kinnear have also had heart problems.
But Sir Alex's health scare is unlikely to affect a £20 million deal he is due to sign with Manchester United next week, which is expected to give him another three years in charge at the club.
In the past few weeks, Ferguson has maintained that his decision to perform a U-turn on his widely-publicised retirement plans two years was one of the wisest moves he has ever made. Ferguson said at the time he felt healthy and able to continue handling the pressures of management at one of the world's biggest clubs and is unlikely to let this minor setback affect his focus.
The Prime Minister was taken to Hammersmith Hospital in October after waking with chest pains and a racing heart.
He had five hours of tests and underwent the same cardio-version treatment as Ferguson to stabilise his heartbeat.
One in 20 affected
Supraventricular tachycardia, or SVT, is often described as an electrical short-circuiting of the heart
It causes the heart to race at up to 300 beats a minute, compared with the normal resting rate of 70
Symptoms include palpitations, breathlessness and light-headedness
It can happen to an otherwise healthy person and can stop as quickly as it starts, giving the sufferer a fright, but leaving them unharmed. Patients receive an electric shock to make the heart return to its normal pattern
According to the British Heart Foundation, about one in 20 people will suffer from an irregular heartbeat at some time in their lives
