NEW YORK — Dr. Arthur J. Moss, a researcher who was credited with saving countless patients from fatal cardiac disorders, including a rare genetic heart glitch that can kill suddenly, died on Feb. 14 at his home in Brighton, N.Y., a suburb of Rochester. He was 86.

Dr. Jonathan W. Friedberg, director of the Wilmot Cancer Institute at the University of Rochester Medical Center, said the cause was cancer.

Dr. Eric Topol, a cardiologist at the Scripps Research Institute in La Jolla, Calif., said of Dr. Moss in an e-mail, “He’s probably done more to advance our understanding of heart rhythm disorders than any cardiologist or researcher in the world.’’

Two of Dr. Moss’s career milestones resulted from serendipitous twists.

As an intern at Massachusetts General Hospital, he had planned to specialize in hematology, or blood disorders. But for reasons that remain unknown, the Navy, after drafting him, thought he was a cardiologist.

Assigned to teach flight surgeons how to interpret electrocardiograms, Dr. Moss read up on the subject and embraced cardiology wholeheartedly.

In 1959, he served on a Navy team that monitored the heart rhythms of one of two monkeys that were sent into space and then safely returned after a 16-minute flight. The monkey, a female named Baker, survived for years. (An Army monkey named Able also survived the flight but died in surgery four days later.)

“Our successful experience with monkey Baker set the stage for the human astronaut spaceflight program,’’ Dr. Moss wrote in 2016 in the journal Progress in Cardiovascular Diseases.

In 1970, when he was a cardiologist at the University of Rochester Medical Center, a woman in her early 40s was referred to him because she had mysteriously been fainting, once when she became excited while bowling.

After diagnosing a malfunction in the heart’s electrical system called long QT syndrome (LQTS), Dr. Moss helped develop a surgical treatment that blocked the signals to her heart from one side of her brain. Electrical impulses from the other side let her heart beat normally.

The woman, Ruth Pontera, is now 88. The syndrome she survived is inherited; three of her grandchildren were also successfully treated for the condition at the University of Rochester Medical Center.

His work on LQTS led Dr. Moss to establish a worldwide patient registry that identified people with a high risk of death from the disorder and how to treat them. The registry, created in 1979, allowed researchers to identify risk factors, including specific genes, enabling doctors to make early diagnoses.

The registry also helped develop alternative regimens that reduced life-threatening episodes by as much as 80 percent. One course of treatment involved implanting defibrillators, which can detect an abnormal heart rhythm and correct it automatically.

In the 1990s, Dr. Moss pioneered the same defibrillator treatment for patients who had had heart attacks. He later conducted trials in the combined use of defibrillators and cardiac resynchronization to improve the heart’s ability to pump blood.

“Arthur was a man of absolute integrity, both of science and of character, and an amazing visionary who could see where the field of electrophysiology was headed long before others,’’ Dr. Wojciech Zareba, director of the Heart Research Follow-up Program at the University of Rochester Medical School, said in a statement after Dr. Moss’s death.

Arthur Jay Moss was born on June 21, 1931, in White Plains, N.Y., to Abraham Moss, who owned a millinery store, and the former Ida Bank.

He graduated from Yale University in 1953 and from Harvard Medical School. He joined the faculty of the University of Rochester Medical Center in 1966. When he died, he was a distinguished professor of cardiology there.

In 2008, Dr. Moss received the Glorney-Raisbeck Award in Cardiology from the New York Academy of Medicine in Manhattan.

He leaves his wife, the former Joy Folkman; their children, Dr. Deborah R. Moss, an associate professor of pediatrics at the University of Pittsburgh Medical Center; Dr. Katherine M. Lowengrub, a psychiatrist and instructor at the Sackler School of Medicine in Tel Aviv; and David A. Moss, a professor at the Harvard Business School; nine grandchildren; and two great-grandchildren.