Doctors didn't see 'any red flags' in a 35 year-old man's intense chest pain. He later collapsed from a cardiac arrest while playing hockey.

• A 35-year-old Cleveland resident collapsed from cardiac arrest at a pick-up hockey game in January, TODAY reported.
• Doctors didn't see 'red flags' in his intense chest pain when he got checked out prior to the game.

A man collapsed during a recreational hockey game from cardiac arrest — after his doctor didn't see "any red flags" from his intense chest pain.

Brandon Miller told TODAY he felt months of pain in his left shoulder before suddenly feeling intense chest pain. Many people who have heart attacks, defined by insufficient blood flow to the heart, feel pain in their left shoulder and chest before experiencing more serious complications.

Miller said when he went to the doctor in mid-January after experiencing 45 minutes of severe chest pain, his blood tests were normal aside from showing high cholesterol. His doctor said he didn't see "any red flags" in Miller's symptoms.

"My esophagus was getting hot, breathing in," the 35-year-old Cleveland resident told TODAY. "Whenever I mentioned that to him, he thought it might be acid reflux. … All the symptoms that I was having seemed they could be symptoms for something else."

Later, Miller said went to play a pick-up hockey game and experienced intense shoulder pain towards the end of the game. Suddenly, Miller collapsed, became unresponsive, and lost his pulse.

Miller had experienced a cardiac arrest, or when the heart stops pumping blood through the body because it's not beating effectively. Unlike heart attacks, which can go on unnoticed, cardiac arrests always lead to an immediate loss of consciousness.

Without immediate treatment, cardiac arrests can be fatal: cardiac arrests that happen outside a hospital lead to death about 90% of the time, Insider previously reported, and survivors sometimes have neurological injuries if the brain is without oxygen for too long.

But Miller survived the cardiac arrest thanks to the swift actions of a paramedic, emergency room physician, and emergency medicine resident also playing hockey that day. The three performed CPR and used a defibrillator to shock his heart back into rhythm.

The emergency medicine resident, Mike Fellenbaum, told TODAY that the three of them needed to take turns performing CPR, because the act of manually compressing the chest to pump blood can be tiresome — especially after playing an hour of hockey.

"It really hit me how lucky Brandon was that we were there and how lucky we were to have been able to help him," Fellenbaum told TODAY. "I'm used to resuscitating half dead people in the emergency department, and we get a lot of people back. But the truth is most people die because they haven't gotten CPR."

Miller survived the attack and went to the hospital, where doctors learned his artery was 90% blocked. Miller underwent coronary artery bypass surgery at the Cleveland Clinic, TODAY reported, and is still recovering.

"If I had heard a story ... with someone my age (whose cardiac arrest) came out of nowhere, I would have been more hard-headed as far as ... getting stuff checked out (by the doctor)," Miller said. "If there's chest pain, go get it checked out. Don't underplay what's happening."