Randy Travis' friends are "frantic" with worry about him.
The country music star was airlifted to hospital on Sunday due to problems with his heart. His spokesman has confirmed he is suffering from "complications of recently acquired viral cardiomyopathy", which is when the heart muscle becomes weakened due to a viral infection.
He is known to be receiving treatment in Dallas, although no further details have been released.
TMZ reports the 54-year-old star's friends and family are beside themselves with worry.
"One medical expert tells TMZ viral cardiomyopathy is not necessarily a death sentence ... and some patients can survive, depending on the level of permanent damage to the heart muscle," reports the site.
"Still, we're told Randy's friends and family are 'frantic.'"
In January, Randy was sentenced 180 days in jail, 30 days in rehab, 100 hours of community service and fined $2,000 stemming from a drink driving charge last year. If he stayed out of trouble for two years it was apparently agreed he wouldn't need to go to prison, with TMZ claiming he completed his rehab stint several weeks ago.
He was preparing to play shows and get back into music, when he fell ill with what he thought was a cold. It is claimed he actually had pneumonia and he gradually felt more poorly until he was rushed to a medical centre on Sunday.
His representative has confirmed he is in a critical condition.
Cardiomyopathy makes it difficult for the heart to function properly and pump blood around the body. It can result in heart failure, with medication, implants and transplants possible treatment options.
Randy has recorded 20 albums since 1985, with his best-known songs including Diggin' Up Bones and Forever and Ever.