The BHF said all the people in the trial had slowed heart rates during their fainting episodes, and they reported 19 blackouts a year on average.
But a year after the treatment, the average number of blackouts fell to about one a year.
About 75% of the group who underwent the CNA procedure no longer fainted at all.
Dr Mohamed Zuhair, a researcher at Imperial College London, which led the trial, said: “CNA offers a way to treat the root cause of this condition. It allowed people to get back to normal lives without needing a pacemaker.
“We hope that this procedure will be adopted by more clinicians.”
Sarah’s condition had also prevented her from driving and she was off work for several months.
“It was one of the hardest times of my life,” she said.
“But now I can live without fear.”