Oct. 29 (UPI) -- Chemicals used to improve images of the heart during MRI scans are unlikely to produce allergic reactions and other side effects in patients who take them, according to a study published Thursday by the journal Radiology: Cardiothoracic Imaging.
In reviewing data from more than 145,000 cardiac MRI scans performed in Europe between 2017 and 2019, well under 1% included reports of side effects or allergic reactions related to the use of contrast agents such as gadolinium, the data showed.
In addition, just 47 of the contrast agent-related adverse reactions included those that were "severe" in nature, such as chest pain, the researchers said.
"Our study demonstrates that the administration of intravenous gadolinium-based contrast agents for cardiac MRI is safe for the overwhelming majority of patients," study co-author Dr. Johannes Uhlig said in a statement.
Cardiac MRI is used to diagnose a variety of conditions, including aneurysms, blood clots and defects. The imaging method also can help evaluate diseases such as cardiomyopathy and myocarditis, or inflammation of the heart.
The majority of cardiac MRI exams use intravenous gadolinium-based contrast agents to improve visualization of the heart muscle and blood flow, the researchers said.
Contrast agents contain an ion of the heavy metal gadolinium, which is toxic to humans. However, in contrast agents, it is bound in a molecule called a ligand to make it safe, according to Uhlig, a cardiologist at University Medical Center in Goettingen, Germany.
The findings of this study come three years after the European Union enacted new regulations restricting the marketing of linear gadolinium-based contrast agents, he and his colleagues said.
Gadolinium-based contrast agents are classified as either linear -- with longer ligands -- or macrocyclic -- with a cage-shaped ligand that traps the ion inside -- based on the type of ligand used, they said.
Studies have shown that trace amounts of the toxic gadolinium ions may remain in the body following repeated gadolinium-based contrast agent use, and linear agents are thought to have a higher likelihood of staying behind compared to macrocyclic ones, according to Uhlig.
The U.S. Food and Drug Administration recommends that physicians consider gadolinium retention when choosing agents to use, he said.
For the new study, Uhlig and his colleagues reviewed data on 154,779 patients who underwent cardiac MRI, with almost 95%, or 145,855, receiving gadolinium-based contrast agents.
Among those who received these agents prior to cardiac MRI, 0.38%, or 556, reported an adverse reaction, with all but 47 being classified as "mild." Those included allergic reactions such as developing hives and wheezing, the data showed.
The 47 "moderate" or "severe" adverse reactions included chest pain and irregular heartbeat. Adverse events also occurred in cardiac MRIs performed without gadolinium, with 2.6%, or 231, of the 8,924 patients reporting adverse reactions such as anxiety and shortness of breath, the researchers said.
The results underscore the importance of preprocedural assessments to look for contraindications to MRI scanning and use of gadolinium-based contrast agents, as well as the likelihood of adverse events to the contrast agents, Uhlig said.
"In particular, macrocyclic gadolinium-based contrast agents exhibit a favorable acute safety profile, and should be considered for cardiac MRI examinations evaluating myocardial scarring, ischemia, cardiomyopathy and myocarditis," he said.