Her husband Harold knew no first aid skills, but with the help of the emergency services, he and friends were able to save Carol.
They were talked through vital life-saving skills by the telephone operator and able to keep her alive until the emergency services arrived.
Mr Simmons, from Newport, Gwent, said his wife, the first person in the world to be saved by telephone cardiopulmonary resuscitation (CPR), owed her life to the phone operators.
Guidelines
He said: "When Carol collapsed, I just didn't know what to do - so I called for help.
"After a few minutes of carrying out CPR, I begged our friends to stop - I was worried that Carol might have already brain damage.
"But the telephone operator kept us calm and encouraged us to keep going until help arrived.
"Without a doubt, Carol owes her life to the people who were at the other end of the phone that day".
Now scientists, funded by the British Heart Foundation, are hoping to prepare guidelines to ensure thousands of others like Carol can be saved by simple telephone advice.
Each year more than 80,000 heart attack victims die before they reach hospital, but many could have been saved if the people with them knew basic first aid.
But only 1% of the population knows how to do emergency life support skills.
One in ten people said if someone had a heart attack they would simply sit and wait for the emergency services to arrive.
Confidence boost
Scientists from the University of Wales College of Medicine are to look at how advice can be given over the phone to people who have called 999 for help.
Previous research has shown that telephone led CPR has led to a dramatic increase in the number of cardiac arrest victims who receive help from a friend or bystander before the emergency services arrive.
But the advice given often fails because it is too complex and time consuming.
Lead researcher Professor Douglas Chamberlain said it was vital people were given good calm and easily understood advice in an emergency.
He said: "More than half of all cardiac arrests occur within reach of a phone so it's vital we get this right.
"In an ideal world, people would take part in refresher courses to boost their confidence and keep their knowledge of emergency life support up to date.
"But realistically, we have to rely on skilled telephone operators to act as the vital link in the 'chain of survival' - to restore confidence in those who have already had basic training, as well as instructing people who have none."