The most common procedure to save the life of a patient suffering a heart attack can, for some, result in bleeding within the heart muscle later on, leading to heart failure, a new study involving researchers from Lawson Health Research Institute and St. Joseph’s Health Care London has found.
Reperfusion therapy is considered the standard of care for people coming into the hospital with a heart attack, where the blocked coronary artery is opened and a stent is placed inside to re-establish blood flow to the heart muscle.
However, researchers involved with the study, published last month in the Journal of the American College of Cardiology, found that the benefits of the therapy can be “paradoxically diminished” by significant reperfusion injury, increasing the damage caused by the heart attack and leading to heart failure.
When blood flow returns to the blocked coronary artery and into narrower vessels, it can cause the smaller vessels to burst, resulting in internal bleeding within the heart muscle, or myocardial hemorrhaging, according to a statement from Lawson.
Researchers studied 70 patients who had suffered heart attacks and found that reperfusion injury led to hemorrhaging in more than half of patients who were being treated for a heart attack.
“Those who experience a myocardial hemorrhage have a much larger piece of their heart muscle die than those who don’t have hemorrhage,” Lawson’s Dr. Frank Prato said in a statement.
“We have been able to show that if there is hemorrhage due to reperfusion injury, the size of the dead tissue within the heart grows, which then can ultimately lead to heart failure.”
The study involved a “multi-center research team” involving Lawson, St. Joseph’s and several other institutions, including Northern Ontario School of Medicine in Sudbury, Cedars-Sinai Medical Center in Los Angeles and Indiana University School of Medicine.
“Even though we’re very good at saving people’s lives in the immediate timeframe when people are having a heart attack, what’s really coming out over the past few years is that heart failure is really accelerating and is really becoming an epidemic around the world. The question is, why is that happening?” Dr. Rohan Dharmakumar of Indiana University said in an interview with 980 CPFL.
“Reperfusion therapy is really to open up the vessel, and the sooner you get to the hospital, the less muscle (is) going to be compromised. What we didn’t know all this time is that when you open up the vessel in about 50 per cent of the people, you can actually have … myocardial hemorrhage.”
Dharmakumar noted that the outcome of the hemorrhage would be heart failure that could start a few years after the initial heart attack, rather than immediate death.
A number of factors increase the risk of myocardial hemorrhaging following reperfusion therapy, Dharmakumar said, including lifestyle factors, how quickly treatment was sought, the amount of damage caused by the heart attack, and whether the blockage occurred in one of the dominant vessels supplying the heart.
“It could be just the coronary vessels are distributed around the heart, and that differs from one person to the other. By and large, it is associated with people coming into the hospital a little bit later than otherwise,” he said.
“Smokers, that’s a recorded phenomena. People who have underlying vascular conditions — for instance, smokers — have that issue. We suspect diabetics and people with hypertension would also be candidates that would end up developing into myocardial hemorrhage.”
It’s hoped that the findings of the study will be used to improve reperfusion therapy and investigate adjunct therapies for patients who are developing myocardial hemorrhage, Dharmakumar said.
“I think it hopefully creates an appreciation in the field that hemorrhage does happen in the heart muscle and that it’s bad. That understanding has not really been common amongst even cardiologists,” he said.
“We know that hemorrhagic stroke is bad. But the understanding that hemorrhage in the heart muscle could also be bad is evolving. I think this … will be one of the major studies that (will) hopefully demonstrate to people that this is something that we should look at very closely.”
— with files from Matthew Trevithick, Devon Peacock