Clinical Trial Leads to Turning Point for Local Firefighter

Nathan Zabka, a 45-year-old paramedic firefighter from Chillicothe, was never one to shy away from danger. But during a response to a restaurant fire in 2021, a new danger came from within. While inside the building, he felt a sudden chest pain and had trouble breathing.  

“I’m inside working the nozzle, and next thing I know, I can’t catch my breath,” Nathan says.  

Nathan stepped outside, dropped to his knees, and took off his gear. About 15 minutes later, the feeling passed. Nathan chalked it up to not being as young as he used to be and was ready to put the incident behind him. But when he mentioned it to his wife later that night, she encouraged him to get a professional opinion. 

“I told her that I really felt my age that day,” Nathan says. “And she said that didn’t seem like me, so I decided to get myself checked out.”  

He scheduled an appointment with his Krista Clark, DO, his primary care provider at Hedrick Family Care, who ordered blood tests and an electrocardiogram (EKG). Nathan’s EKG showed elevated T-waves, which measure how the heart “resets” between each beat. He was sent to Saint Luke’s North Hospital for additional testing, including an angiogram and echocardiogram (echo). That’s when Nathan got a clear diagnosis.  

“They found my left ventricle enlarged,” Nathan says. “I was diagnosed with hypertrophic obstructive cardiomyopathy. On paper, I was having a heart attack.”  

Hypertrophic obstructive cardiomyopathy (HOCM) is a genetic disorder that causes the walls of the heart muscle to stiffen, restricting blood flow from the heart to the rest of the body. Restricted blood flow deprives the body of oxygen and nutrients, leading to several complications, such as an increased risk for heart attacks, fatigue, and dizziness.  

Nathan’s team referred him to Saint Luke’s Mid America Heart Institute, where he met with Michael Nassif, MD. Dr. Nassif is a board-certified cardiologist and heart failure specialists with Saint Luke's Cardiovascular Consultants whose research focuses on cardiovascular disease and heart failure cases. Nathan wasn’t sure what to expect, but Dr. Nassif offered a surprising message.  

“He was very professional and sympathetic to my diagnosis,” Nathan says. “But he also said that, in a weird way, it was a great time to have HOCM.”  

Dr. Nassif explained that a clinical trial was underway for a new medication called aficamten, designed to treat the underlying causes of HOCM.  

“Nathan’s case presented a unique clinical challenge,” Dr. Nassif says. “His heart showed no signs of obstruction while he was at rest, but with even minor exertion, it developed a significant, symptomatic obstruction. This specific dynamic meant he was ineligible for certain standard-of-care myosin inhibitors currently on the market. His best option for treatment ended up being early access to next-generation myosin inhibitors through the MAPLE-HCM clinical trial.” 

While going through the eligibility process over the next several months, Nathan’s condition worsened. He was often short of breath, he struggled to climb stairs, and everyday chores had become physically exhausting. When he was approved for the trial and began taking aficamten, the difference was immediate. 

“I knew from day one that it was working for me,” Nathan says. “For the first time in a long time, I could breathe deeply. I could climb a flight of stairs. Normal life felt normal again.”  

Now one year into the trial, Nathan’s results have been remarkable. His ejection fraction, a key measure of the heart’s efficiency, has returned to normal range. Most importantly, he feels like himself again.  

“It’s been a miracle,” Nathan says. “I don’t feel like I have heart issues at all. I’m able to live my life.”  

“Seeing outcomes like Nathan’s reinforces why clinical research is so important,” Dr. Nassif says. “We owe it to our patients to explore every possible option for their care.”  

Today, Nathan continues taking aficamten and remains active in the clinical study. He and his wife keep a busy home in Chillicothe with 11 children. Although he gave up firefighting, he still serves his community as a paramedic instructor and the Livingston County Coroner. Looking back, he’s grateful to Saint Luke’s and Dr. Nassif for his care and compassion during a stressful time in his life.  

“I never felt like a lab experiment,” Nathan says. “Dr. Nassif treated me like a human being who cared about me and wanted to see me succeed. I would trust him again in a heartbeat.”  

Comprising nearly 100 board-certified experts in cardiology, cardiovascular surgery, and critical care anesthesia, Saint Luke’s Mid America Heart Institute offers a comprehensive range of treatment options for advanced heart failure, structural intervention, preventive cardiology, electrophysiology, and heart and vascular surgery. Patients interested in participating in a clinical trial must meet certain criteria as determined by their provider. 

View current clinical trials.