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The world’s first clinical trial of a new treatment for patients with blocked coronary arteries has shown the novel approach to be safe and to yield promising success rates.

The University of Toronto-Sunnybrook Health Sciences Centre study involved 20 patients, each with a coronary artery completely blocked by plaque -- a condition called chronic total occlusion (CTO).  Each patient received an injection of an investigational drug called MZ-004, an enzyme that softens the plaque over a 24-hour period. The injection was given in hopes of making it possible for a traditional angioplasty to be performed by advancing a guide-wire through the otherwise impenetrable blockage, then inserting a stent to re-open the artery and restoring blood flow.

Fifteen subjects, or 75 per cent, were able to successfully undergo angioplasty despite previous failed attempts.  Published in the journal Circulation and funded by the Canadian Institutes of Health Research, the study is poised to change the way patients with blocked arteries are treated throughout the world, with a large multi-site, international clinical trial to begin later this year.

“Due to the traditionally low success rate of angioplasty in patients with completely blocked arteries, many patients turn to bypass surgery or treatment with medications alone,” said Dr. Bradley Strauss,  a U of T professor in the Department of Medicine and the principal investigator who also developed the novel formulation and approach.  “This treatment provides patients with the option of receiving angioplasty, rather than having more invasive treatment with bypass surgery or living with pain and discomfort.”

Currently, approximately 20 per cent of patients having an angiogram are diagnosed with chronic total occlusions.  Of this number, less than 10 per cent have angioplasty, with approximately 25 per cent receiving bypass surgery and the remaining 65 per cent presumably on medication alone.

“Although not all patients with chronic total occlusions need to have an angioplasty to open up the blockage, those who experience chest pain and have difficulty breathing may be able to benefit greatly,” added Strauss, chief of Schulich Heart Centre at Sunnybrook and the founder of Matrizyme Pharma Corporation, the company responsible for the development of the drug. “In fact, successful angioplasty can relieve the symptoms almost immediately and significantly improve quality of life.”

For patient Louis Waldman, a 49-year-old police officer and father of five, a successful angioplasty after receiving collagenase in March 2011 had immediate results. 

“I was feeling tired and worn out and a trip to my family doctor revealed that I had a clogged right artery.  After one angioplasty attempt that didn’t work, I found Dr. Strauss,” said Waldman.  “My discomfort went away almost immediately after the successful angioplasty.  I could breathe and had no chest pains.  It’s a vast improvement, I’m pretty much back to normal.”