Arkansas Teen Awaits Heart Transplant 3 Years After Surviving Bone Cancer: 'I've Been So Lucky' (Exclusive)

“I'm excited for the next steps in my life,” says MacKenzie Maddry, 17, who is hoping to get a heart transplant in the next few months

• MacKenzie Maddry, now 17, was diagnosed with bone cancer in her knee in 2020 and spent 100 days in the hospital undergoing cancer treatment

• Two years later her family learned she had end-stage heart failure

• While she awaits a heart transplant, a left ventricle assist device (LVAD) keeps her alive

MacKenzie Maddry always loved sports. The eighth grader ran track and cross country, and she also played soccer. So when she told her parents her left leg hurt in fall 2020, they thought it was a sports-related injury.

“I noticed this bump on my leg, and it just got bigger and more painful,” the teen from Bella Vista, Ark., tells PEOPLE. “We just thought I had pulled something."

The lump was on the inside of her left thigh, just above her knee. And when she sat down — to play the viola for example — it became more painful.

“I would go to orchestra and sit down, and then it would take me a while to get up and be able to straighten my leg out. It was so bad,” MacKenzie, now 17, says. “That was when I was like, 'Yeah, we definitely need to see a doctor about this.'”

After visiting multiple doctors, she was referred to a hospital in Little Rock, where she was diagnosed on Dec. 17, 2020 with osteosarcoma, a cancer that starts in the bones. About 400 children under 20 are diagnosed each year, according to Children’s Hospital of Philadelphia.

MacKenzie started 48 hours of chemo on Dec. 23 — spending Christmas morning in the hospital. She had 21 rounds of chemo over nine months before undergoing surgery to remove the tumor. The teen spent nearly 100 days in the hospital for her cancer treatment.

“We were there three weeks out of the month because we have a chemo one week, a rest week, and then chemo the next week, and then the week after that,” MacKenzie says.

She remembers feeling very down. "It was very hard to deal with because all your friends are moving on in their life, and you're battling this terrible cancer,” she says. “My friends are there for me, but it's hard that you have to put your life on hold while everybody else is moving forward.”

A year after she finished chemo, her surgery site got infected. She had three surgeries to clean out the infection and reconstruct her femur, the last of which was Oct. 13, 2022.

But a few days later, she woke up in pain. “We assumed the leg pain was fine, but it just felt so amplified, and there was a little bit of chest pain,” MacKenzie says.

Three days later the chest pain had become so severe that she was rushed to the hospital. She arrived with low blood pressure and high heart rate. Soon after, doctors determined she had end-stage heart failure.

Her mother remembers the moment she heard the diagnosis. “You think that you get the worst news ever with cancer," says Dori Maddry, 43, a program manager at Walmart. "You're devastated. You can't even think like, 'How are we going to get through this?'”

“To then be told by doctors, 'It's end stage heart failure' — you don't get over that.”

While MacKenzie had been diagnosed with chemo-induced cardiomyopathy in August 2021, everything had been under control thanks to her blood pressure medication. “My heart was kind of already being monitored, but it was fine. It wasn't getting worse until I had that surgery on my leg,” she says. “It just progressed overnight.”

Unfortunately, since she had not yet reached the two-year cancer-free mark, she was ineligible for a heart transplant. “We had to look for a long-term solution while I waited,” she says.

After weeks of trying multiple medications to help her heart function, doctors decided the only way she would live to see her 17th birthday in September 2023 was to get a  left ventricular assist device (LVAD) implanted in her chest. It helps pump blood from the lower left heart chamber — called the left ventricle — to the rest of the body, according to the Mayo Clinic. She had the device surgically implanted on November 14, 2022.

Related: Mass. Woman, 30, with Rare Genetic Heart Condition Says She Has No Pulse: 'I Run on Batteries' (Exclusive)

“It pumps my blood for me because my heart just doesn't have the willpower to do it on its own right now. I'm still technically in heart failure because if you took the device out, it wouldn't do well on its own,” MacKenzie says.

Still, she feels so much better since getting the Abbott LVAD HeartMate 3 . The device enabled her to go home from the hospital to wait for her new heart.

“It gave me my energy back that I lost from chemo," she says. "I just am so grateful....Without it, I don't know where I would be right now.”

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After spending a total of 297 in the hospital since December 2020, MacKenzie is now on the heart transplant waiting list.

“I’ve been so lucky," she says.

“When my mom gets phone calls, I'm always listening in to make sure, because we met someone with an LVAD, that has a son that had heart transplant. And she's like, 'Make sure you video whenever they call you."'And I just thought that would be a cool idea. So I'm always like, 'Do I need to come video this phone call?'” MacKenzie says.

While she waits for her new heart, a GoFundMe has been set up to help with medical expenses. She has become an advocate and LVAD ambassador, sharing her story with other pediatric patients waiting for a heart.

“It's so nice to meet people that know your struggle, that you've been going through,” she says.

She keeps a list of “tips and tricks” to share with other patients. And she shares her journey on Instagram.

Related: Girl Who Received First-of-Its Kind Heart Transplant Is Thriving — and Just Turned 1! (Exclusive)

After she gets her heart transplant, she hopes to be able to swim — she wasn't able to last summer. She's also set her sights on nursing school.

“I'm just excited for the next steps in my life,” she says.

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