The 52-year-old has always enjoyed a high-energy lifestyle, managing the intensity of producing films and television shows (Ladder 49, Flight Plan, Top Gear, Wheeler Dealers) by eating healthy, running and biking along the Los Angeles River. After his daughter was born in 2020, Nieminen assumed his constant exhaustion was the typical kind that comes with sleepless nights caring for a newborn. Still, he and his wife, Kaisa, found it odd that picking up his daughter left him depleted.

“My battery was constantly drained,” Nieminen said. “Being physically active all my life, it was quite alarming. Deteriorating this quickly when I’m just over 50 seemed sort of dramatic.”

Nieminen also noticed his heart seemed to beat too fast at times and occasionally it would skip a beat, so in 2023 he made an appointment with Cedars-Sinai cardiologist Ronit Zadikany, MD. Zadikany diagnosed him with atrial fibrillation, an irregular heart rhythm that occurs when the upper and lower chambers of the heart beat out of sync. The condition tends to worsen with time and can cause the heart to beat too slowly, too quickly or irregularly, impeding blood flow. Common symptoms include fatigue, heart palpitations, dizziness and reduced stamina. Left untreated, atrial fibrillation can cause a slew of cardiovascular complications—including stroke.

Nieminen’s cardiologist referred him to Christine M. Albert, MD, MPH, an expert in atrial fibrillation and chair of the Department of Cardiology in the Smidt Heart Institute. Albert recommended cardioversion, a procedure commonly used to reset the heart to a normal rhythm. The results made Nieminen feel like himself again, but only for a day. A second cardioversion combined with a medication known to work for many people also had temporary effects.

Albert was determined to find Nieminen a treatment that would have long-term results. She suggested he might benefit from catheter ablation, a procedure that destroys cells and creates a small scar within the heart, breaking up or insulating the electrical signals causing the heart to beat out of sync. She connected him with Michael Shehata, MD, a cardiac electrophysiologist in the Smidt Heart Institute.

Shehata was leading a clinical trial investigating a new catheter ablation called pulsed field ablation. Rather than create scars, pulsed field ablation targets heart cells involved in an abnormal heart rhythm.

Nieminen underwent the procedure in January 2024.

“When other options fail, this procedure can be life-changing for patients,” Shehata said.

Pulsed field ablation is done by threading a catheter through a vein in a patient’s leg until it reaches the top chambers of the heart. Once in place, a cardiologist sends a high-voltage electrical impulse through the catheter. The energy penetrates cell walls and destroys specific heart cells, preventing abnormal signals from causing an irregular heartbeat. The procedure takes 30 to 60 minutes.

“The energy is delivered specifically to heart cells without injuring nerve cells, smooth muscle cells, or other, healthy cells,” said Shehata, who is also director of the Interventional Electrophysiology Laboratory at the Smidt Heart Institute. “For some patients with atrial fibrillation, this procedure may be safer than conventional ablation procedures that destroy small areas of heart tissue.”

Following U.S. Food and Drug Administration approval of several pulsed field ablation systems, the procedure is now available for use outside of a clinical trial.

Advances in treatment couldn’t come at a better time. Atrial fibrillation is the most common type of irregular heartbeat and deaths related to the condition have been increasing for more than two decades, according to the U.S. Centers for Disease Control and Prevention.

Today, Nieminen is back to long runs and cycling through his neighborhood. He also works with local organizations to advocate for safe walking and biking paths in Los Angeles. Most importantly, he can now lift his daughter into the air like the high-energy dad he is.

A device that was implanted to record Nieminen’s heart rhythm shows proof of his progress: He has been free from atrial fibrillation since getting pulsed field ablation.

“Don’t hesitate to share with your doctors when something feels off because you feel like you’re being a hypochondriac or you think it’s too insignificant to bring up,” he said. “As you get older, it’s especially important to listen to your body, eat right and stay active, and that doesn’t necessarily mean doing a 10K. Everything your mom would tell you growing up: Stay active, eat healthy, get sleep and get checkups with your doctor. Mom knew what she was talking about.”

Read more on Cedars-Sinai Stories and Insights: Back Into Rhythm | Adjusting to an AFib Diagnosis