​Suffering cardiac arrest in Chicago used to be a near-certain death sentence.

Suffering cardiac arrest in Chicago used to be a near-certain death sentence. But in just a few years, the survival rate tripled. What happened?

Just outside Wrigley Field, 15-year-old Shira David knelt on the artificial turf of Gallagher Way on Wednesday, trying to teach 8-year-old baseball fan Shea Corbin how to keep a correct rhythm when performing CPR.

“You know the song ‘Stayin’ Alive’?” Shira asked, referring to the 103 beats-per-minute disco classic often recommended as a mental accompaniment for chest compressions.

Ryder Burk, 5, left, and his older brother, Rhet Burk, 8, learn to make chest compressions on a CPR mannequin during an event to teach people about CPR, before a game at Wrigley Field on Aug. 21, 2019, in Chicago.(John J. Kim / Chicago Tribune)

Shea shook his head.

“You know the song ‘Another One Bites the Dust’?”

Shea shook his head again.

Such are the challenges of teaching CPR to a mass audience, as the Wrigley Field event was designed to do (“Baby Shark,” it turns out, also has an appropriate beat). But the payoff can be immense.

A recent study found that Chicagoans who suffer cardiac arrest outside of a hospital are three times more likely to survive than they were just a few years ago. The reason, scientists say, is largely because more bystanders are performing CPR in the crucial moments after a person’s heart stops beating.

“This is a culture change,” said Dr. Marina Del Rios of Illinois Heart Rescue, which has helped to train 1.5 million state residents in CPR over the last five years. “If you ingrain into people early on that bystander CPR is something you should do, just as natural as calling 911, then people are more likely to actually perform it.”

Cardiac arrest happens when an electrical malfunction of the heart causes it to stop beating. It’s different from a heart attack, which occurs when a blood vessel blockage starves the heart of oxygen, causing tissue damage.

The odds of surviving cardiac arrest aren’t good, even when doctors and nurses are close at hand: According to a report from the National Academies of Sciences, Engineering and Medicine, 76% of cardiac arrests that happen in hospitals are fatal.

Outside the hospital, the numbers are downright dismal. Nationwide, only 11% of those cardiac arrest victims survive. The figures tend to be even worse in major urban centers: In 2011, the Joint Commission found that just 3% of Chicago’s out-of-hospital cardiac arrest victims lived.

Nursing student Melanie Simard instructs as Karen Elsken makes chest compressions on a CPR mannequin during an event to teach people about CPR, before a game at Wrigley Field on Aug. 21, 2019.(John J. Kim / Chicago Tribune)

“In big cities like Chicago, there are some unique challenges to taking care of cardiac arrest,” said Dr. Terry Vanden Hoek, head of emergency medicine at UI Health. “There’s more traffic. There’s people having an event on the fourth floor or fifth floor, and you have to take the elevator.

“There are other cities that have reported survival rates similar to that. New York’s survival rate was less than 2%. Last time it reported (its rate), Detroit was at almost 0%.”

But in recent years, Chicago’s survival rate has more than tripled, reaching 10%. Observers give credit to several initiatives.

The city’s 911 dispatchers have been trained to improve their recognition of cardiac arrest and to coach bystanders on how to perform CPR, according to researchers. First responders have also used simulation-based training to emphasize “high quality chest compressions with early defibrillation.”

Dr. Vincent Bufalino, a cardiologist with Advocate Medical Group and a longtime volunteer with the American Heart Association, said the growing availability of defibrillators has also helped. He said the devices, which send a shock to the heart to restore a normal rhythm, have pushed the survival rate over 50% in some places where they’ve been installed.

He has bought several devices himself, putting one at his children’s school, one at the family’s church and one in the trunk of his car. About five years ago, he said, he used his personal defibrillator to save a man who went into cardiac arrest during a dinner party.

“He was alive and talking before the ambulance got there,” Bufalino said.

But the increase in bystander CPR rates might have made the biggest difference. A recently published paper by Del Rios, Vanden Hoek and others found that Chicagoans suffering cardiac arrest in 2016 received CPR from bystanders 24% of the time, compared with 13% three years earlier.

That coincides with escalated public CPR training sessions conducted by the Illinois Heart Rescue Project, which specializes in teaching an abbreviated form of CPR. It emphasizes chest compressions, leaving aside mouth-to-mouth resuscitation.

“Trying to factor in the breathing was causing way too many delays in the most important part of CPR, which is doing chest compressions,” Vanden Hoek said. “We wanted to keep it simple. And it turns out it’s more effective that way.”

The technique is straightforward. If a person is unconscious and not breathing normally, a bystander should call 911 and start chest compressions at a rate of about 100 per minute while sending others off to fetch a defibrillator. The bystander should keep going until medics arrive.

Dozens of trained volunteers scattered around Gallagher Way tried to entice Cubs fans into taking the lesson, which lasted only two or three minutes. The fans pressed down upon the breastbone of miniature resuscitation dummies — just a torso and a face — until they heard the click that told them the compression was deep enough.

“There you go,” volunteer Cristin Hock said when Lee Glenn, a produce salesman from Moultrie, Georgia, made his dummy’s chest click. “That’s perfect. So don’t be afraid to administer CPR.”

Glenn, who was in Chicago visiting clients, said he has taken CPR courses before but found the refresher to be a worthwhile experience.

“Anytime you can help somebody in life, no matter what it is, how simple it is, you need to help,” he said.