New light shed on potentially damaging effects of standard heart attack treatment

Date:
January 4, 2022
Source:
Indiana University School of Medicine
Summary:
A new study is challenging standard treatment methods used to
prevent muscle damage during heart attack.



FULL STORY ==========================================================================
A study led by Indiana University School of Medicine is challenging
standard treatment methods used to prevent muscle damage during heart
attack.


==========================================================================
In a paper published in the high impact Journal of the American College
of Cardiology, Rohan Dharmakumar, PhD asserts that a common treatment
given to patients experiencing heart attack may not be as successful in
halting muscle damage as once thought.

Heart attacks occur when the blood vessel supplying oxygen to the heart
muscle -- also known as the coronary artery -- is suddenly blocked. In
heart attack patients, the amount of heart muscle that is irreversibly
damaged is directly linked to how much time elapses between the onset of
heart attack symptoms and when the blockage is opened up. More damage
means higher risk of complications like heart failure after a heart
attack. Therefore, treating heart attacks focuses on opening up the
coronary arteries as quickly as possible through a procedure called
reperfusion -- often with a stent.

The common belief in reperfusion therapy is that once the coronary
arteries are opened, the damage to the heart muscle is stopped. However, according to Dharmakumar, that is not always the case.

"In our work, we demonstrate that if reperfusion results in internal
bleeding - - or, hemorrhage -- within the heart muscle, the heart muscle
can continue to die even after the culprit coronary artery is opened,"
said Dharmakumar, executive director of the Krannert Cardiovascular
Research Center at IU School of Medicine. "Hemorrhage is known to occur
in heart muscle of around half of all heart attack patients who undergo reperfusion. We sought to determine what effect that internal bleeding
has on progressive heart muscle damage after reperfusion." In his work, Dharmakumar and his team studied blood samples of heart attack patients obtained before and after they received reperfusion therapy. Using
cardiac magnetic resonance imaging (cardiac MRI), they noninvasively
identified which patients experienced hemorrhage within their heart
muscle following reperfusion. A key protein called troponin is known to
go up with heart muscle damage; in patients with heart muscle hemorrhage, troponin values rose more rapidly reaching higher values when compared
to patients without hemorrhage.

The team also used a large animal model to prove that hemorrhage is
directly involved in the extent of infarction after reperfusion. Serial
cardiac MRIs noninvasively tracked infarct size in animals with and
without hemorrhage; similar findings as those seen in patients means
that the team can use the animal model to develop new treatments to
reduce hemorrhage that can be brought back to help patients.

In the modern era of revascularization, Dharmakumar asserts in his study
that infarct size is not only determined by restricted blood supply to the heart, but also by the effects of reperfusion therapy. The introduction
of hemorrhage within the at-risk area might in some cases nearly negate
in total the benefits of reperfusion therapy. Dharmakumar said that
for physicians, having an awareness of the role reperfusion can play on continued muscle death can help in providing better treatment to patients
in the future.

"This all means that although we might not be able to do much when it
comes to lost time before a patient arrives at the hospital, minimizing
the effects of hemorrhage following reperfusion can give us a new
opportunity to reduce the size of infarction, and downstream negative consequences, in nearly half a million heart attack patients in the
United States alone," said Dharmakumar.

Next for the study, Dharmakumar said that his team will expand the
findings to a larger patient population, working to develop greater
insight into how hemorrhage drives expansion of infarction and testing strategies to halt the effects of those hemorrhages.

According to Subha Raman, MD, chief of the Division of Cardiology and
director of the Cardiovascular Institute at IU School of Medicine and
IU Health, the future real-world applications of this study showcase
the research leadership of Dharmakumar and the Krannert Cardiovascular
Research Center.

"The work being done by our researchers at the Krannert Cardiovascular
Research Center, under the leadership of Dr. Dharmakumar, is
truly groundbreaking and will fundamentally improve how we take
care of patients suffering heart attacks, improving the health of
Hoosiers and beyond," said Raman. "I am proud of the high-impact
cardiovascular science happening in our research labs, and look forward
to seeing that work pay real dividends in the future of heart health." ========================================================================== Story Source: Materials provided by
Indiana_University_School_of_Medicine. Note: Content may be edited for
style and length.


========================================================================== Journal Reference:
1. Ting Liu, Andrew G. Howarth, Yinyin Chen, Anand R. Nair, Hsin-Jung
Yang,
Daoyuan Ren, Richard Tang, Jane Sykes, Michael S. Kovacs, Damini
Dey, Piotr Slomka, John C. Wood, Robert Finney, Mengsu Zeng, Frank
S. Prato, Joseph Francis, Daniel S. Berman, Prediman K. Shah,
Andreas Kumar, Rohan Dharmakumar. Intramyocardial Hemorrhage and
the "Wave Front" of Reperfusion Injury Compromising Myocardial
Salvage. Journal of the American College of Cardiology, 2022; 79
(1): 35 DOI: 10.1016/ j.jacc.2021.10.034 ==========================================================================

Link to news story: https://www.sciencedaily.com/releases/2022/01/220104095605.htm
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