Canadian researchers have found a faster way to diagnose a heart attack.
Scientists at the University of Calgary, in conjunction with teams in Germany and Australia, have studied the use of cardiac magnetic resonance imaging (MRI) to view heart damage. They found that cardiac MRI is quicker, and just as good at showing damage, than standard, more invasive methods that involve radiation or the injection of radioactive dyes.
Researchers explain that the water in heart tissue has magnetic properties that allow the MRI to view the muscle.
The study is published in the Journal of the American College of Cardiology.
The research could lead to MRI being used to diagnose heart attacks while they are happening, which can take hours using other methods.
"Until now, there has been no way to directly see how much of the heart muscle was rescued by the intervention," said study leader Dr. Matthias Friedrich, associate professor of medicine in the departments of cardiac sciences and radiology at the University of Calgary, and director of the Stephenson Cardiovascular Magnetic Resonance Centre at the Libin Cardiovascular Institute of Alberta.
"Even more importantly, this lays the groundwork for working on even better strategies for identifying patients who need interventional treatment, and for the development of new ways of optimizing acute interventions in (heart attacks)," Friedrich said in a statement.
The longer a heart-attack patient goes without medical intervention, such as a balloon angioplasty or the implantation of a stent to open a blocked artery, the more damage is done to the heart muscle.
By using cardiac MRI, doctors would also be able to assess the extent of post-heart attack damage. This would allow them to better understand how effective the patient's treatment was. As well, physicians could project how well the patient's heart will recover.
The team is now studying how this technology can improve heart attack prevention.
Abstract:
The Salvaged Area at Risk in Reperfused Acute Myocardial Infarction as Visualized by Cardiovascular Magnetic Resonance
Matthias G. Friedrich, MD, Hassan Abdel-Aty, MD, Andrew Taylor, MD, Jeanette Schulz-Menger, MD, Daniel Messroghli, MD, Rainer Dietz, MD
Calgary, Alberta, Canada; Berlin, Germany; and Melbourne, Australia
Objectives We aimed to characterize the tissue changes within the perfusion bed of infarct-related vessels in patients with acutely reperfused myocardial infarction (MI) using cardiovascular magnetic resonance (CMR).
Background Even in successful early revascularization, intermittent coronary artery occlusion affects the entire perfusion bed, also referred to as the area at risk. The extent of the salvaged area at risk contains prognostic information and may serve as a therapeutic target. Cardiovascular magnetic resonance can visualize the area at risk; yet, clinical data have been lacking.
Methods We studied 92 patients with acute MI and successful reperfusion 3 ! 3 days after the event and 18 healthy control subjects. Breath-hold T2-weighted and contrast-enhanced ("late enhancement") CMR were used to visualize the reversible and the irreversible myocardial injury, respectively.
Results All reperfused infarcts consistently revealed a pattern with both reversibly and irreversibly injured tissue. In contrast to the infarcted area, reversible damage was always transmural, exceeding the infarct in its maximal extent by 16 ! 11% (absolute difference of the area of maximal infarct expansion 38 ! 15% vs. 22 ! 10%; p " 0.0001). None of the controls had significant T2 signal intensity abnormalities.
Conclusions In patients with reperfused MI, CMR visualizes both reversible and irreversible injury. This allows for quantifying the extent of the salvaged area after revascularization as an important parameter for clinical decision-making and research.
