Her struggle touched hundreds, if not thousands, in and around Western New York, through her fiance's Facebook posts, her family's fundraisers to cover medical bills, and the media.
But a donor heart never became available.
And the 21-year-old Salamanca native's body could only hold out for so long.
Then, 2½ weeks ago, Rivera's organs began to shut down. The doctors said there was nothing else they could do.
So Rivera's fiancé, Dennis Brown, and her parents made arrangements to bring her from Strong Memorial Hospital in Rochester to the apartment she had shared with Brown in Hamburg for three years before she got sick.
On Friday, her body became unresponsive, and the family made the sad but inevitable decision to turn off the pumps.
“I laid on the bed with her, and they disconnected the batteries,” Brown said.
Rivera was just 10 when she received her first heart transplant after suffering from cardiomyopathy. Last spring, she began experiencing troubling symptoms. She was fatigued and short of breath. It turned out her transplanted heart was failing.
She ended up at Strong Memorial, where she went into cardiac arrest for three minutes.
To keep her alive, her doctors tried an unconventional procedure – they implanted two artificial heart pumps, designed by Dr. Robert Jarvik, in a way that hadn't been tried before. The famed cardiologist assisted in the nearly 10-hour surgery.
Now, all they needed was a new heart.
But that proved a challenge. Rivera's blood type was O-negative. She was also extremely petite, which meant most adult hearts would not fit her tiny frame.
And then she became too sick to undergo transplant surgery. Eventually, they had to take her off the transplant list.
Throughout the nine-month ordeal, Rivera's loved ones strived to keep her spirits up.
They held fundraisers to help with medical bills.
For her birthday, Brown put together a slide show of photos of Rivera and himself and posted it on YouTube. In picture after picture, they radiate love. They're a beautiful couple, her with her raven-like hair and movie star features and him with his chiseled physique from his training as a professional MMA wrestler. The photos scroll by to “I Won't Give Up,” a love song by Jason Mraz.
At the hospital, she got to know former Sabre Gates Orlando, who also spent months at Strong Memorial with an artificial heart implanted before he had a successful donor transplant.
They also tried to keep Rivera focused on the future by planning Rivera and Brown's wedding.
“We were supposed to have our wedding this summer,” Brown said.
Rivera and her mother started making arrangements for the ceremony. As she got sicker, they switched plans to have it at the hospital.
“Then she got really sick,” Brown said. “It wouldn't have been anything that she would have wanted to be, being that sick.”
When it became clear that she wouldn't have long to live, she decided she wanted to return to the apartment in Hamburg.
Brown brought their bed into the living room so that she would more comfortable.
There, family and loved ones came to say their goodbyes.
She was alert for the first few days she was home. Then she began to fade.
“She started to sleep more and more and more,” Brown said.
Brown and her parents knew she was worried about how her passing would affect them. They told her: “Everyone is so proud of you. It's OK to give up now. You fought. You fought for nine months.”
Brown marveled at the strength she showed throughout her illness.
“I've been told I'm a pretty tough guy,” the professional wrestler said.
“It's nothing compared to what she's been through and fought through. ... She is, by far, the strongest person I've ever met in my life,” he said.
He now hopes that her story will inspire more people to choose to become donors.
“She was 21,” he said. “She didn't get to live. She didn't get to live a full life. That's all she wanted. But she lived her life. She always had a smile on her face. She didn't sweat the little things. She was an amazing person.”