The cancer drug Gleevec may carry a risk for decreased heart function, drug maker Novartis Pharmaceuticals warned Monday.

Gleevec or imatinib mesylate is used to treat adults with a type of blood cancer called chronic myeloid leukemia and a type of cancer of the stomach and bowels known as gastrointestinal stromal tumour.

People who are using Gleevec and have high blood pressure, diabetes or a history of heart disease should talk to their doctor about the risks of heart failure, the company said.

Anyone on the drug who has symptoms suggestive of heart failure such as leg swelling, chest pain or shortness of breath should see their doctors immediately. People should not stop taking the medication without talking to their doctor, said the advisory, which was endorsed by Health Canada.

An article published in the journal Nature Medicine this summer reported that 10 patients who were treated with Gleevec later developed decreased heart function and congestive heart failure, the safety alert noted.

Several of the patients who were affected had other medical conditions including high blood pressure, diabetes or a previous history of heart disease or they had received other drugs that might have contributed to their increased risk of heart failure, the company said in a release.

Doctors advised to monitor patients closely

Congestive heart failure occurs when the heart's pumping action weakens.

Information from animal studies suggests there may be a possible relationship between Gleevec and decreased heart function that needs further investigation, Novartis said.

Canadian prescribing information for Gleevec already lists "cardiac failure" as an "infrequent" event with a risk of 0.1 to 1 per cent, but the company said it is working with the regulator to include any new safety information.

Doctors prescribing Gleevec should monitor their patients closely. In people with underlying heart disease or who are elderly, doctors may want to consider assessing heart function before starting treatment with Gleevec, the company said in a letter to health-care professionals.

Gleevec was designed to target gene mutations linked with chronic myelogenous leukemia and certain types of stomach cancers.

In 2004, Gleevec cost upwards of $30,000 per patient per year as a leukemia treatment.