About 10,000 people die each year in the UK because too many people "lack the confidence and skills" to perform CPR, according to the British Heart Foundation.
A study by a team at Warwick University found one in eight cardiac arrest victims dies as a result of poor CPR training levels in the general population.
"The community response to cardiac arrest is a critical step in the chain of survival," lead researcher professor Gavin Perkins said.
Survival rates are almost zero if people collapse and get no support until paramedics arrive, but immediate CPR in some cases can "double the chance" a person will live, Prof Perkins said.
Overall, less than one in 10 people survive cardiac arrest in Britain.
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BHF chief executive Simon Gillespie said: "Shockingly, thousands of lives are being lost every year because people lack the confidence and skills to step in and save a live when someone collapses ...
"Survival rates in the UK have remained stubbornly low for far too long and it's time we improved them.
"That's why we are urging secondary schools across the UK to apply for our free training kits and help create a nation of lifesavers."
A poll suggested more than half (53 per cent) of UK adults have never had any training, while nearly half (47 per cent) would be worried about causing more harm than good.
