A father and son from Mexico City who each faced life-threatening heart conditions and underwent complex surgeries at Cleveland Clinic are now training together for the 2026 Sydney Marathon, set to run on August 30. Leon Hamui, treated for a leaking aortic valve and an aneurysm, and his son Johnny Hamui, who battled a rare cardiac cancer, were both operated on by the same surgeon roughly a year apart.
Leon Hamui traveled from Mexico City to Cleveland Clinic after decades of unexplained fainting spells, according to Cleveland.com. Clinicians there discovered he had a leaking aortic valve and an ascending aortic aneurysm, and he underwent open-heart surgery at age 62. Leon had experienced fainting spells for around 20 years and had been diagnosed with an abnormal heart rhythm, the outlet reports.
That history traces back to 2004, when Leon fainted during marathon training, according to Cleveland Clinic. Specialists there identified a lower-chamber heart arrhythmia that was managed for two decades with a cardiac ablation before open-heart repair became necessary. During that surgery, Dr. Eric Roselli repaired and salvaged Leon's native aortic valve without replacing it, while also transposing an anomalous right coronary artery into a normal position.
A Son's Cancer Diagnosis Upends the Family
Roughly a year before his father's operation, Johnny Hamui was diagnosed with cardiac angiosarcoma in the right atrium, a rare and aggressive cancer, per the same Cleveland.com report. Johnny, then 36, had experienced heartburn, dehydration and fainting spells before doctors found the tumor. He was treated by Dr. Roselli and a multidisciplinary Cleveland Clinic team, who used a 3D-printed heart model to plan the operation.
The tumor removal took 10 hours in December 2025, according to Cleveland.com's account of the surgery. Following the resection, Cleveland Clinic oncologist Dr. Dale Shepard designed a post-operative chemotherapy plan that allowed Johnny to continue cancer treatment near his family back in Mexico, according to the same Cleveland Clinic patient story.
The rarity of Johnny's diagnosis is hard to overstate. Primary cardiac angiosarcoma is diagnosed in only about 40 to 50 people annually in the United States, with an autopsy prevalence estimated between 0.0001% and 0.030%, according to OncLive. Median survival after diagnosis typically ranges between 10 and 16 months, with five-year survival rates estimated around just 5% to 14%, per Cleveland Clinic data on the disease. Complete surgical resection combined with chemotherapy offers the best recorded outcomes, though the cancer carries an ongoing risk of recurrence that requires long-term monitoring.
Tennis Roots and a Shared Recovery
Before his diagnosis, Johnny was an elite athlete. He was ranked 14th in the world as a junior tennis player, according to Cleveland.com, and Leon coached him in junior tennis before Johnny went on to play NCAA Division I tennis at the University of Florida and the University of Illinois, where he earned Second-Team All-Big Ten honors during his 2010–11 senior season, per University of Illinois Athletics records. Leon also worked alongside Johnny in their family business.
Leon said Johnny's strength during treatment gave the family hope, and Johnny has said his father supported him throughout, according to Cleveland.com's reporting. Leon has also said his own heart diagnosis caused fear. Both men underwent their complex heart surgeries at Cleveland Clinic one year apart, treated by the same surgeon, Dr. Eric Roselli.
Training for a Marathon Neither Has Finished Before
Now father and son are training together for the 2026 Sydney Marathon on August 30. It will be Leon's fifth marathon, but Johnny's first. The race marks the seventh member of the Abbott World Marathon Majors series, having joined the elite marathon circuit alongside Boston, London and New York in 2025, according to Marathon Tours, and organizers expect more than 40,000 international participants in 2026.
The course is no easy victory lap. With 313 meters of cumulative elevation gain, the Sydney Marathon route is considered the hilliest in the Abbott World Marathon Majors series, surpassing the elevation challenges of both the Boston and New York City marathons, according to the Running Week. The route crosses the Sydney Harbour Bridge and finishes at the Sydney Opera House.
Dr. Roselli, who performed both surgeries, serves as Chief of Adult Cardiac Surgery and Surgical Director of the Aorta Center at Cleveland Clinic, where he regularly performs more than 350 complex heart and aortic procedures a year, according to the Interdisciplinary Aortic Dissection Symposium. Cleveland Clinic's cardio-oncology center, where Johnny's cancer treatment was coordinated, is based in Cleveland. The health system was named to U.S. News & World Report's Best Hospitals Honor Roll for the 36th consecutive year in August, ranking No. 1 overall in Ohio and among the top national programs for cardiology and heart surgery.
