His team has found a great deal of evidence in their preclinical studies that intramyocardial hemorrhage, or bleeding within the heart muscle after reperfusion therapy, causes extensive damage to the heart.
Reperfusion therapy is the re-opening of blocked arteries after a heart attack conducted by a care team. Clinical investigations have now confirmed that intramyocardial hemorrhage represents the most severe form of injury post heart attack repair.
New study validates years of pre-clinical research
While restorative treatments have saved millions of patients from immediate death after a heart attack, about half of patients develop chronic heart failure within five years. They are also likely to experience adverse heart muscle remodeling and the formation of fatty tissue. Dharmakumar and his team seek to understand and consider how to better mitigate heart damage while considering appropriate therapeutics.
Cardiovascular researchers in Europe, who conducted the largest multicenter cardiac MRI (CMR) study of STEMI patients to date, corroborated the IU Krannert team’s research. The study, led by Medical University of Innsbruck in Austria, included more than 1,000 patients and was published this spring in the Journal of the American College of Cardiology.
The study reports that reperfused STEMIs — or ST-segment elevated myocardial infarctions, resulting in intramyocardial hemorrhage — contributes to a multifold higher risk of major adverse cardiovascular events (MACE) and is the main driver of MACE in post-heart attack patients.
Dharmakumar and Andreas Kumar, MD, a senior cardiologist from Northern Ontario School of Medicine, co-authored an editorial in the same issue of JACC, entitled, “Hemorrhagic Myocardial Infarction: Light After 50 Years in the Tunnel,” in which they discuss the significance of intramyocardial hemorrhage as a harbinger of MACE as well as the importance of early detection of it post-PCI.
“This is the most detrimental form of injury after heart attack treatments and supports our mission to bring awareness within the medical community to recognize that not all heart attacks are the same.”
Ripple effects for clinicians, researchers
In fall 2023, the Canadian Cardiovascular Society was the first to adopt the classification of acute myocardial infarction based on heart tissue damage, thanks to research and 
development led by Dharmakumar, Kumar and collaborators. The American College of Cardiology and European Society of Cardiology received the classification with broad interest.
There is also a growing international interest in using cardiac magnetic resonance (CMR) imaging as a diagnostic tool in determining the level of cardiovascular tissue damage.
World renowned cardiologist Valentin Fuster, MD, PhD, president of Mount Sinai Fuster Heart Hospital and physician-in-chief of The Mount Sinai Hospital, said in an episode of the JACC’s companion podcast that cardiac magnetic resonance imaging has become a reference toward the issue of microvascular injury — specifically in heart attack patients.
Fuster said, the “fantastic new technology of MRI to address intramyocardial hemorrhage is the key in the prognosis of myocardial infarction,” and that this was “one of the best papers in JACC in 2024.”
Led by IU Krannert researchers, Dharmakumar, Keyur Vora, MD, their collaborators, including Kumar and other researchers, wrote a State-of-The-Art Review article published in JACC: Cardiovascular Imaging in April, that said serial noninvasive imaging has played a key role in accumulating the critical knowledge of progressive damage to the myocardium from the time microvascular injury first occurs to how disease progresses over several years in patients who have experienced one or more heart attacks.
Thanks to the advances in imaging over the last two decades, cardiovascular researchers have experienced a deeper understanding of reperfused myocardial injury, which have helped them assess the compositional, structural and functional changes to the heart over time.
“It is our hope that the use of advanced imaging can drive therapies to mitigate reperfusion injury and improve outcomes,” Dharmakumar said.
