I have a shockingly low heart rate — doctors didn’t think it was real

His heart doesn’t race, it crawls.

An Englishman redefined “heart-stopping” after recording pulses as low as 22 beats per minute — which could shatter the Guinness World Record for the slowest heart rate.

“People have been pretty shocked at how low it goes,” Cameron Johnson told The Post about his cardiovascular anomaly, noting doctors “knew it was generally low, but when they realized how low they couldn’t believe it.”

“The doctors thought it was interesting,” he added. “They kept coming in to check that it was real. About two or three of them popped their heads in to see it for themselves.”

The Newcastle native, who works as an ecologist, said the first hint of his preternaturally slow pulse came when he began wearing a fitness tracker seven years ago. He would also occasionally suffer from dizziness despite being an exercise enthusiast who ran regularly and played sports.

“I wear a watch and I’ve always known my pulse was low, but my watch showed it averaged 30 bpm, and when I saw that pop up, I was concerned,” he said.

“I only really noticed how low it was when I started wearing my watch — I’ve never been able to monitor it before that.”

However, Johnson didn’t think much of it until a doctor took his pulse in July. The medic was so alarmed by the readings that he called an ambulance to drive the runner home from the appointment, fearing his patient wasn’t fit to drive himself.

Paramedics even suggested that the Brit “wear something to tell people my heart rate is normally that low” should he ever become unresponsive in the future — lest they mistake him for dead.

During a follow-up appointment in September, a 24-hour electrocardiogram exam revealed that his heart rate averaged 30 beats per minute but had plunged as low as 22 bpm during the reading.

“I have had a few ECGs in the past and they’ve all been low, but the doctors had never been concerned,” he said. “But I had one this summer and that’s when the doctors were worried, and they called an ambulance to take me to hospital.”

That was several beats slower than the Guinness World Record of 26 bpm, set by 81-year-old former endurance athlete Daniel Green in 2014.

A normal resting heart rate for adults is between 60 and 100 bpm, making Johnson’s equivalent to a turtle hibernating under ice.

In fact, any reading under 60 is considered bradycardia, denoting an abnormally slow heart rate, and can point to an issue with the heart’s electricity. It can also bring about spells of fainting, dizziness and fatigue due to the lack of blood supply to the brain and other organs.

“I was in the hospital for eight or nine hours and then I had to wear a monitor for 24 hours,” Johnson said.

Needless to say, he was concerned about his slow heart rate.

“It drops lower at night and can pause for over five seconds. I was shocked at just how low it was going,” he said. “That’s quite a long time when you think of a heartbeat.”

Despite the inherent risks of having such a molasses-y metronome, doctors concluded that the jogger’s condition was ultimately “nothing to be concerned by.”

They cleared him as “healthy but worth monitoring” — in other words, that his heart will go on, albeit very slowly.

“The doctors described it as ‘nocturnal pauses,’” he said.

Though alarming, low heart rates aren’t unheard of. Young athletes, for example, may achieve an adagio ticker, with many clocking in at between 30 and 40 bpm.

Indeed, the condition hasn’t stopped Johnson from remaining active: The fitness buff regularly embarks on 5-kilometer (3.1-mile) runs, cycles and plays football and badminton.

“I run quite a lot and I play for a football team up here and try to keep healthy and fit. I don’t have any side effects from it,” he said of his heart rate. “I don’t think it optimizes my performance. I think it’s a side effect of being fit for a lot of people.”

He says his next goal is to shatter Daniel Green’s Guinness World Record, a feat that’s easier said than done despite his record-breaking reading.

To get this number officially entered in the books, Johnson claims he’d have to spend another 24 hours hooked up to an ECG machine, which would be monitored by two Guinness representatives.

His official number would be the average of the lowest three heart rate readings.

Other requirements include video evidence, paperwork galore and a peer-reviewed study showing that he had a significantly lower pulse than normal for the population.

Johnson said the idea of being “written about in a scientific journal seems a bit ridiculous.”

“I don’t think anyone is interested enough to write about it,” he said.