Pioneered by a Sunnybrook specialist, a new treatment that unclogs blocked arteries is giving new life to cardiac patients
John Balkwill sees piles of snow when he looks out the window. But even though spring is still a few weeks away, he's already planning a reunion with his golf clubs.
"I haven't played golf for close to two years," says John, a resident of Leamington, Ont., who was referred to Sunnybrook last year after an angioplasty procedure - one of many he has had over the last decade - failed to unclog the arteries to his heart. "In fact, I haven't been able to do much of anything for the last two years since I lived in pain every day and had been mostly bedridden."
Yet today, John is back to doing most of the things he used to do before heart disease disrupted his life. He's gone back to work at the business he co-owns, a company that provides electronic controls for greenhouses. He's exercising. He's got a life again - all because of a small dose of an enzyme called collagenase.
Last November, John became part of a clinical trial at Sunnybrook that saw collagenase - a fluid commonly used in laboratories to prepare cell cultures - injected via catheter into the blocked arteries of 20 patients.
Collagen is the primary component in the plaque that builds up and blocks the arteries of people with coronary heart disease. During an angioplasty, doctors try to push a guidewire through the plaque to make way for a catheter with a small balloon on its end.
Once the catheter is positioned properly, the balloon is inflated, causing it to press against the walls of the artery and creating blood flow. But in certain patients - like John - the plaque is so hard the guidewire can't penetrate it at all. This is a life-threatening situation.
Collagenase works by softening the collagen in this rigid plaque, causing it to degrade and break down.
"Collagenase enzymes are very specific in that they target collagen and break down its structure," explains Dr. Bradley Strauss, chief of the Schulich Heart Centre at Sunnybrook and leader of the collagenase trial.
Dr. Strauss, who is also the Reichmann Chair of Cardiovascular Sciences, has been experimenting with this application of collagenase since the 1990s. In addition to proving the enzymes are effective in softening plaque in coronary arteries, he has also produced a grade of collagenase safe for use in humans.
I never gave up on collagenase because I always felt thet it made sense. Dr. Bradley Strauss, Shulich Heart Centre
In 2008, Health Canada gave him the go-ahead to do his first patient trial.
The day after John received his dose of collagenase, he was back in the operating room at Sunnybrook for an angioplasty. This time, the guidewire and catheter made it through easily.
"For the last two years I could not take two steps without having angina pain, and I was basically on medication all the time to help me cope with the pain," says John. "Now two days a week I'm working out for an hour-and-a-half each day, running on the treadmill, doing bike work, lifting weights.
"I can basically do anything I want. It's like a new life now, a totally new life."
John isn't the only success story to emerge from the collagenase patient trial. Next-day angioplasties on 13 of the first 15 patients - Dr. Strauss is still finalizing his findings on the other five patients - were successful, with the plaque softening enough to let the guidewire through.
Mohsen Ghatavi is another one of these success stories. After a year of sporadic chest pains - one episode happened while he was on the highway driving to work - Mohsen is pleased to report that he is now pain- and worry-free.
"I feel great and I want to thank Dr. Strauss and his nurses and research team for what they have done," he says. "I hope they can treat more people."
That's exactly what Dr. Strauss and the people at Sunnybrook are hoping for, too. Making collagenase available to more people, says Dr. Strauss, would reduce the need for bypass heart surgery and improve the quality of lives of people living with heart disease.
"All of the patients in the trial had previously had failed angioplasties," he says. "Without collagenase, the only recourse for some of them might be bypass surgery, while those who aren't good bypass candidates would be put on medication and would have significant limitations to their lives."
The years leading up to the patient trial were not always easy, says Dr. Strauss. There were many times when he was stuck on a problem, unsure about how to go forward.
"But I never gave up on collagenase because I always felt that it made sense," he says. "So to see it work on patients and to know that we've been able to make a difference in these people's lives - well, it's just amazing."
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