KEY POINTS:
The heart condition that has plagued rower Rob Waddell for years - and dashed his Olympic hopes yesterday - is a complaint affecting about 1 in 100 New Zealanders.
The 33-year-old's heart condition, called atrial fibrillation, re-appeared during the third and final row-off with Mahe Drysdale at Lake Karapiro, enabling Drysdale to power ahead and win the deciding race.
Waddell was diagnosed with the condition in 1997 and has spoken publicly about it in the past.
It occurs in about 1 in every 100 people in the general population, and about 10 in every 100 people aged over 80, according to the Ministry of Health.
Auckland City Hospital cardiologist Dr Chris Ellis said yesterday that atrial fibrillation was the commonest heart arrhythmia.
"It's actually very common, and a lot of GPs and cardiologists would be seeing these patients all of the time.
"You can lose up to 25 per cent of your cardiac efficiency. There's a whole lot of reasons why you might jump into atrial fibrillation. Common reasons are to have high blood pressure, hardened arteries, leaking valves, holes in the heart, and a variety of other conditions. So for Rob Waddell, and people like him, and some endurance athletes, they just leap into this rhythm as they push the heart really hard."
He said physical exertion could bring on an episode, but not always.
"Obviously it doesn't a lot of the time, otherwise he wouldn't have won the Olympic gold [in 2000].
"He's obviously got one of the strongest hearts in New Zealand, but electrically it's rather excitable and jumps out of rhythm once in a while."
And when it does strike, it results in a sudden fall-off of ability.
"What will likely happen is that when you try to exercise, you aren't able to work as hard and will get more short of breath. The whole circulation just isn't as efficient as it would normally be."
He said people with the condition were either on regular medication, or took medication when an episode came on. Surgery was another option, but wasn't common.
Other high-profile sportsmen to suffer from atrial fibrillation include former Auckland and Blues rugby player Justin Collins, who discovered he had the condition in 2001.
"For older patients, if they aren't well-treated, some of them can have strokes as a result of it."
But it's not a condition that should put sufferers off strenuous activity.
He said he admired Waddell for talking publicly about his condition.
"It's very helpful and should be congratulated because it means that other people who have got this issue can understand that they've got a wonderful heart, very often, which is just electrically a little unstable."
ATRIAL FIBRILLATION
* Irregular beating of the heart, which may become very fast
* Treated with medication or surgery
* Attacks can come on during physical exertion
* Occurs in about 1 in every 100 people, but more common in older people
