The 30-year-old is calling for all players to be examined after midfielder Evander Sno suffered a heart attack while playing for Ajax last week.
Clarke said: "It's a simple test, and it definitely saves lives."
"The tests do find specific problems, like problems with the valves of your heart or an enlarged heart," he added.
"That's what the ex-Manchester City player, Marc-Vivien Foe had. He died from problems with an enlarged heart and if he had had an ECG on a regular basis it would've been pretty nailed on that they would've picked something up."
Testing is essential with how the fast the game is now and how fit you have to be.
Clive Clarke
Former Cameroon midfielder Foe died after collapsing during a Confederations Cup semi-final against Colombia in Lyon in 2003.
In recent years, Motherwell captain Phil O'Donnell and Benfica and Hungary striker Miklos Feher have also died from undiagnosed heart conditions.
Last week, 23-year-old Evander Sno suffered a heart attack playing for Ajax reserves against Vitesse Arnhem.
Paramedics had to resuscitate the former Bristol City midfielder three times using a defibrillator.
"Testing is essential with how the fast the game is now and how fit you have to be," said Clarke, who now works as a football agent and is a patron of the CRY (Cardiac Risk in the Young) charity.
"With all the money in the game, a once every six months ECG for each player isn't that costly, so it should be brought in as a routine part of other medical checks."
ECG heart screening costs around £35 and is mandatory in club academies.
It is also used by some Premier League clubs, but none of the major football authorities are willing to fund the programme.
Clarke continued: "It should be paid for by the Premier League, even for the Football League clubs because they're strapped for cash.
"It's probably something they might not see as necessary because most guys are fully fit and if you find one at every three clubs it would be brilliant to safeguard those guys future."
Source: BBC Sport
Source: BBC Sport