BOSTON — Jim LaFontaine wouldn’t be alive today if it weren’t for an anonymous donor who overlooked his family’s religious convictions to give him a new heart.

LaFontaine, pastor of Emmanuel Community Church in Essex, developed heart disease in his mid-30s. After years of surgery and complications, he was told he needed a transplant to survive.

Four years ago, he received a heart at Brigham and Women’s Hospital donated by a 47-year-old man who died unexpectedly from a brain aneurysm.

“I was really fortunate,” said LaFontaine, 59. “It was a good match, which is rare.”

He was one of the lucky few.

Nearly 118,000 people in the United States are waiting for a transplant, and more than 20 people die every day waiting for a suitable organ. In Massachusetts, 3,544 are on waiting lists, according to New England Donor Services.

But public health officials here are encouraged by a growing number of people who are willing to donate their organs when they die to give strangers a chance to live.

The number of people signed up to donate organs has risen by more than 90 percent in the past decade, from about 1.7 million in 2007 to more than 3.2 million this year, according to the Registry of Motor Vehicles, which manages the state’s organ donor registry.

Matthew Boger, a spokesman for New England Donor Services, attributes the increase to the policy of asking people to donate when they get a driver’s license.

“The states play a critical role in this process because the vast majority of everyone who registers as an organ and tissue donor does so at the RMV,” he said.

In New England, more than 1,000 lives were saved last year by donations, he said.

Even so, the odds are long for most who are awaiting organs. Each year, the number of people on the waiting list grows, while only about 2 percent of donated organs can be used.

A reason for the low margin is that organs are generally taken from donors who’ve been declared brain-dead and whose bodies are on respirators, limiting the usefulness of their organs.

“You’re more likely to need an organ transplant than to become a donor,” Boger said.

A majority of those waiting for a match in Massachusetts — or 2,519 people — are in need of kidney transplants, according to New England Donor Services. At least 753 are waiting for a liver; 220 for a heart; 63 for a lung and 27 for a pancreas.

Boger said misconceptions — such as concerns that doctors won’t save patients who are donors, or that it may violate the tenets of a person’s religion — deter some from registering.

“Every major religion in the country supports organ donations,” Boger said.

In October 2014, Pope Francis met with the Transplantation Committee for the Council of Europe and called the act of organ donation “a testimony of love for our neighbor.”

In April, the state Department of Public Health launched a public relations campaign to boost participation in the donor registry. While the number of people registering has risen, they still represent about half of the state’s 6.7 million residents.

“You’re never too old to be an organ donor,” Public Health Commissioner Monica Bharel said at a recent Statehouse event. “We need to do something to change this trend.”

LaFontaine, who has a wife of 30 years and two sons, learned that he had a heart murmur in his 30s during a routine exam. A cardiologist discovered he was born with a bicuspid aortic valve, lessening the amount of blood flow to his body.

He later developed a condition that required a pacemaker and defibrillator to regulate his heartbeat. But his heart started failing, so a transplant was the only option.

At Brigham and Women’s, LaFontaine was given an artificial heart that kept him on life-support for months while he waited for a transplant. As he lay in a hospital bed in Boston, LaFontaine said he wrestled with deep feelings of guilt and spirituality over the idea of benefiting from someone else’s death.

“It was almost a deal-breaker for me,” he said. “As a minister, I just couldn’t get my head around the fact that I was sitting there waiting for someone to die.”

Two years after the operation, he met the donor’s wife and family in a get-together arranged by the hospital. It was an awkward, emotional experience, he said.

He learned the man had gone against his conservative religious beliefs when registering as an organ donor, and he hadn’t even told extended members of his family.

“He went against his own faith,” LaFontaine said. “That was humbling to me.”

LaFontaine has since befriended the man’s son, who regularly attends his church.

Dr. Henry Dorkin, a pediatric pulmonologist and president of the Massachusetts Medical Society, said in recent years the cutting-edge science behind organ transplants and post-surgery treatments has vastly improved patients’ chances of survival.

“In most cases, the surgery goes pretty well,” he said. “The issue is generally how sick was the recipient before they got the organ.”

Dorkin said a single donor can help dozens of people with organs such as the heart, lungs, pancreas and kidneys, as well as through skin, veins and tissue donations.

Still, he worries that rising numbers of organ donors may deter people from participating.

“We’re doing better than we were but not as good as we need to be,” he said. “We don’t want people to think they don’t need to do anything because we have enough organs.”

LaFontaine said not a day goes by that he doesn’t think about the man who donated his heart.

“Without this man’s generosity, I wouldn’t be here,” he said. “I got a second chance because of him, so I try to live every day in a way that somehow honors him.”

Gloucester (Mass.) Daily Times, Crux staff contributed to this report.