David Last, 54, from Norfolk was gifted an Apple watch from his wife, Sarah, for his birthday in April.
Upon affixing the new device, Last discovered that his resting heart rate was as low as 30bpm on nearly 3,000 separate occasions.
The average resting heart rate for an adult male is usually between 60-100bpm.
Last assumed that the device was faulty, but his wife urged him to consult his GP, who subsequently referred him to a cardiologist.
He underwent an MRI scan in May, with the results finally coming back in July, when his consultant gave him a 48-hour ECG test to monitor his abnormal heart rate.
After missing five calls from the hospital asking him to come back in as a matter of urgency, the IT developer realised something was gravely wrong.
“The hospital sounded really panicky on the phone,” he said.
“As soon as I got there, they had a bed ready.”
Last was informed he had third-degree heart block, after the junction box in his heart had worn down, and was at risk of sudden cardiac death.
He said: “The pre-surgery consultation explained that my case was unusual, and they had extensive meetings about what they were going to do.
“My heart had stopped 138 times in 10-second intervals over a 48-hour period.”
He learnt that this would primarily happen whilst he was asleep, causing another part of his heart to kickstart the blood flow, before the process would repeat.
Last underwent life-saving surgery to fit a pacemaker into his heart in August and describes feeling “relieved” and having “a lot more energy”.
The newly-fitted device will sense any abnormal rhythms and help both heart ventricles to pump blood in sync.
He said: “My wife keeps saying that she saved my life, and she's not wrong.
“If she hadn't bought me my Apple watch for my birthday, I wouldn't be here. I will always be eternally grateful to her for it. Apart from charging it, it's always staying on me now.”
Last described himself as “really active”, stating that his family had no history of heart complications. Unaware of the severity of his condition, the couple got married in June, describing things as “life as normal”.
He said: “I had no symptoms whatsoever. We even went to Italy for 10 days for our honeymoon - I had no idea anything was wrong. Even the doctors were amazed.”
Last has since returned to work and attributes his wife to his recovery.
“Sarah really looked after me,” he said. “She keeps saying how proud of herself she is — and she should be: she saved my life.”
Additional reporting by SWNS
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