VANCOUVER -- The heart condition that has left former Vancouver Canucks hockey enforcer Gino Odjick with just months, or even weeks, to live is extremely rare, has no known cause and is almost always fatal, experts say.

Odjick, 43, who played in the NHL from 1990 to 2002, including eight years in Vancouver and two in Montreal, has released an open letter that said he was diagnosed with AL amyloidosis.

In the letter, which was published Thursday on the Vancouver Canucks' website, Odjick said he was diagnosed two months ago and was originally told he likely had years to live, but he was recently told it could instead be a matter of months or weeks.

AL amyloidosis causes a gelatin-like protein -- amyloid -- to be deposited in the heart muscle, which affects the organ's ability to expand and contract, said Dr. Saul Isserow, the director of Sports Cardiology B.C.

"Think of the heart like a rubber band," Isserow said in an interview Friday. "If you infiltrate the rubber band with a material that doesn't either stretch or contract, you can imagine the rubber band won't work efficiently."

The condition, also referred to as primary amyloidosis, also interferes with the electrical function of the heart, said Isserow.

Symptoms include heart failure, shortness of breath and fluid retention, often in the form of swelling in the legs, he said. The condition typically culminates in sudden death due to a fatal heart arrhythmia.

Isserow said it's not known what causes AL amyloidosis. It some cases, it is associated with multiple myeloma, a type of blood cancer, but it also occurs on its own.

Whatever its cause, it wouldn't be related to a hockey player's time on the ice, he said.

"This is given to you more by nature than by nurture," said Isserow

In the United States, the disease affects about 2,000 to 2,500 people a year; based on the size of the Canadian population, Isserow said that means it likely affects about a tenth of that number in this country.

Isserow said there is no effective treatment. After diagnosis, life expectancy is often 12 to 18 months, but that can vary significantly from patient to patient, he said.

"Unfortunately, it's almost uniformly fatal once it's been diagnosed," he said.

Dr. Nicholas Valettas, a cardiologist who teaches at McMaster University in Hamilton, Ont., said chemotherapy is sometimes used in an attempt to stop the amyloid protein from being formed. However, he said even if chemotherapy is effective, it does not undo the damage caused by the protein already in the heart.

In a very small number of cases, doctors have attempted heart transplants to treat the condition, but both Isserow and Valettas said such a procedure is far from typical.

"Cardiac transplantation with chemotherapy has been tried in a few cases, and some centres have reported reasonable success, but we don't have a lot of patients to say that this is the standard of care," said Valettas.

AL amyloidosis primarily affects the heart, while other forms of amyloidosis can also target the brain, liver and kidneys.

Norma Gilbert, the co-founder of the Canadian Amyloidosis Network, watched her husband die of the disease a decade ago.

Gilbert's husband, a provincial court judge in Alberta, was diagnosed in 2004. He became weak with fatigue as his heart deteriorated.

At the time, many cardiologists hadn't even heard of AL amyloidosis, but Gilbert said that seems to be changing.

She said her husband was told there was no rhyme or reason to explain why he developed the disease.

"We were told that it just didn't matter -- it didn't relate to your diet or your activity," said Gilbert.

"My husband's famous line, he said to me, 'I won the wrong lottery,' and I said, 'You certainly did."'