Anastacia has supraventricular tachycardia

Anastacia has revealed she’s put off having heart surgery for a cardiac condition.

The singer has supraventricular tachycardia, which causes varied and rapid heartbeats.

But the 40-year-old, who had a breast cancer op in 2003, is treating it with drugs for now.

‘The doctors say it's a weakness triggered by stress,’ she tells Hello!

‘I'll be sitting chatting and suddenly my heart will beat like I'm running a marathon. I've fainted backstage because I can't get rid of the palpitations.

‘They can fix it by putting two electrodes into my heart and shocking it, but I don't want more surgery right now, so I'm on medication. The side effect is fatigue.’

Anastacia’s new album Heavy Rotation is out now.