Some heart patients who have to wait too long for a diagnostic test face serious consequences, Canadian researchers have found.

Doctors use an angiogram to study the inside of the heart and blood vessels. When a dye is injected through a catheter, doctors can tell whether a patient needs surgery to keep blood flowing to the heart.

In Hamilton, researchers followed 8,030 patients scheduled for angiograms and found a significant number of them waited five months for the test.

Dr. Madhu Natarajan

Most physicians would consider six weeks a reasonable wait, said cardiologist Dr. Madhu Natarajan of McMaster University. Only 37 per cent of patients had the procedure within the recommended time frame.

The team found that 109 people had a heart attack or suffered heart failure while on the waiting list. Fifty of those patients died.

Natarajan said it's almost certain some patients would have lived if the wait had been shorter.

For example, if a patient with a bad heart valve "had their angiogram in a more reasonable time, they might have gone on to have that valve diagnosis and valve replacement or bypass surgery sooner and potentially avoided an adverse event," said Natarajan.

The researchers suggest part of the answer is to:

• open more labs for angiograms
• develop central booking systems that specify minimum criteria for the test
• improve systems to prioritize and monitor changes in patients' status
• specify maximum waiting times for patients at low risk

The study appears in Tuesday's issue of the Canadian Medical Association Journal.

In a commentary that accompanies the study, cardiologist Dr. Justin Ezekowitz of the University of Alberta said a lot of people at low risk may end up "clogging the system." It's equally important to find a way to move the sickest people to the top of the waiting list, he said.

Patients also need to look out for themselves, the researchers said. By telling the doctor if their health deteriorates while on a waiting list, patients may get their diagnostic tests faster.