US researchers found the benefits of twice-weekly walks are hugely significant, regardless of weight or other forms of exercise.
Those women who walked at least twice a week had a 20 to 25 per cent lower risk of heart failure than those who walked less frequently.
And the decade-long study of almost 90,000 post-menopausal women also found fast walkers who kept going for at least 40 minutes gained the greatest heart protection.
Dr Somwail Rasla, a cardiology fellow at Saint Vincent Hospital in Massachusetts, said: “We already know physical activity lowers the risk of heart failure. But there may be a misconception that simply walking isn’t enough.
“Our analysis shows walking is not only an accessible form of exercise, but almost equal to all different types of exercise that have been studied before in terms of lowering heart failure risk.
“Essentially, we can reach a comparable energetic expenditure through walking that we gain from other types of physical activity.”
Heart failure affects about 900,000 Britons and has the second highest cost to the NHS after strokes.
Women aged 75 to 84 are three times as likely to have heart failure as those aged 65 to 74.