Nearly 95 percent of people who undergo cardiac arrest die, and most people never knew they had heart disease to begin with. But Bob Johnson, a competitive rower in Pittsburgh, was among the lucky 5 percent who survived.

Johnson, 59, credits his life to four teammates who, while training at a local boathouse in January 2014, called 911, performed CPR, and used an automatic external defibrillator (AED) to resuscitate him within three minutes— miraculously, his doctor said, leaving the father of one without brain damage. Now, with those same friends, Johnson is preparing to compete in the Head of the Charles Regatta in Boston, the world’s largest regatta, on Oct. 22 - 23. He’s tackling the feat after undergoing triple bypass surgery and receiving a subcutaneous implantable cardiac defibrillator (S-ICD), a relatively novel device that’s placed under the skin without touching the heart, and shocks the organ into a regular beat if reaches dangerous levels.

“If that had happened on the water, I would not have survived,” Johnson told FoxNews.com of his teammates’ quick thinking. “I was in the right place at the right time with the right people. So here I am two-plus years later, and everything’s great, couldn’t be better.”

The Food and Drug Administration (FDA) approved the S-ICD in September 2012, and as he laid in his hospital bed after undergoing surgery in early 2014 at the University of Pittsburgh Medical Center, Johnson researched his ICD options. At first, he was resistant to getting one.

“I said, ‘I fought this, I don’t need this,’ and psychologically I didn’t want a foreign body in my body,” he recalled.

But later, doctors determined Johnson had an irregular heartbeat— a sign of premature ventricular contractions— leaving him at risk of a future adverse event. He’d need an ICD. Through his research, Johnson considered the S-ICD a compromise of sorts. Unlike the more traditional transvenous ICD (T-ICD), which has been around for about 30 years, the S-ICD only shocks the heart. The T-ICD paces and shocks the heart.

He went to the Cleveland Clinic, where he found Bruce Wilkoff, director of cardiac pacing and tachyarrhythmia devices at the hospital, and an expert in S-ICDs. In March 2014, Wilkoff implanted one in Johnson, discharging him one day after the procedure, as is standard after implantation of either ICD.

“[The ICD] gives you the freedom to be protected even when you’re by yourself,” Wilkoff told FoxNews.com. “It’s not just for you— it’s for your family. If you’re a wife or husband, how do you sleep with both eyes closed? But if you have something that is a safety net, that gives you a lot of peace of mind.”

While T-ICDs are implanted underneath the skin on top of the left heart muscle and are attached to the heart with wires called leads, S-ICDs are implanted under the left armpit about halfway down the chest, Wilkoff said. Their leads don’t go into any veins but lie outside of the ribs so the heart itself is not touched.

Advantages of S-ICDs include their easy removal. However, while the transvenous model can last upwards of eight years before needing to be replaced, the S-ICD lasts only upwards of six.

Other than a patient’s personal preference, S-ICDs are often ideal for many younger patients, like Johnson.

“The younger somebody is, the longer you’d rather stay out of the veins because the veins can be used for other things” related to treatment for age-related illness, Wilkoff said.

The ratio of people who get T-ICDs to S-ICDs is 10 to 1, he added, but regardless of the model, having an ICD increases the chance of a patient being rescued from 5 to 98 percent upon hospital discharge.

Despite the added safety, Johnson said getting used to a foreign body about the size of an iPhone being in his chest was difficult at first. One fear was losing control of the oar and hitting himself in the chest.

“For the first three months, I thought about it every minute of every day,” said Johnson, who pointed out the S-ICD has a stronger shock than the T-ICD due to its location outside of the heart. “I saw it; I was in fear of it going off. And then it lessened as I was about to get back to my normal routine.”

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About six months after implantation, he became more comfortable training. 

And yet, as a precaution, while Johnson trains— in the summer, five to six days a week; now, about three times a week— he monitors his heart rate using a wristband and/or his iPhone, which in the winter is secured with Velcro on the odometer of his indoor rower.

Giving up the sport after his heart episode wasn’t an option, said Johnson, who’s always had a competitive drive. He began competitive rowing at age 14, and spent 38 years of his adult life working on Wall Street in sales and trading.

Since his cardiac arrest, among his achievements, he and his team won bronze at the U.S. National Masters Rowing Regatta this season, and during the competition he competed in five different events, making the final in all of them.

Thanks to the S-ICD, his confidence level is about 95 percent today, he said.

Bill Anderson, 61, a rowing teammate who’s known Johnson for about four years, performed life-saving CPR— a skill he knew through Boy Scouts and doing Cub Scouts with his son— on Johnson, and said Johnson is “a joy” to row with.

Mike McGuire, another of Johnson’s teammates, who also helped save his life in 2014, said the rest of the crew feeds off Johnson's energy.

“He’s got an incredibly competitive spirit,” McGuire, 49, who’s known Johnson for the past three years, told FoxNews.com. “From an outward impression, he’s in great shape— probably in better shape now than when this happened … and that’s an inspiration, knowing what happened.”

Johnson said he got back into rowing after he retired to try to get in shape again, but now the hobby holds new meaning.

“There’s a certain psychological benefit to being involved in the sport,” he said, “and that is that it’s demanding, and being able to handle it is an affirmation of all the good things my doctors did for me.”