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Tuesday, August 19, 2008
Recent research supports an improvement in cardiac diagnostic protocol.
Imagine an emergency department where physicians use sophisticated MRI technology to quickly and easily determine which at-risk patients have acute coronary syndrome, a set of symptoms that occurs when there is a severe loss of blood to the heart’s muscle that likely causes a heart attack. Physicians could then use this detailed information to better triage patients, sending them directly to the catheterization lab or home, depending on the imaging results.
Ricardo C. Cury, MD, cardiac radiologist at the Massachusetts General Hospital Heart Center, and a team from Harvard Medical School has recently published research that supports this possible improvement in emergency room protocol.
Published in the August 19, 2008 edition of Circulation, the journal of the American Heart Association, Cury’s research found that cardiac magnetic resonance (CMR) was a successful alternative noninvasive test that accurately assessed patients with acute chest pain. Current methods include a detailed clinical risk assessment based on an ECG and cardiac enzymes – methods that don’t always work optimally, often encouraging physicians to unnecessarily admit patients to the hospital.
“We demonstrated that cardiac magnetic resonance with T2-weighted imaging and left ventricular wall thickness analysis provided not only high diagnostic accuracy for detection of patients with acute coronary syndrome, but also allowed the differentiation of patients with acute versus old myocardial infarction,” explains Cury.
In an emergency room environment where patients can be there for 12 to 24 hours, a timely and accurate diagnostic test could drastically improve the triage process. Physicians could quickly sort out which patients have acute versus old myocardial infarction (heart attack), and which patients have unstable angina (loss of blood to the heart, causing chest pain) versus non-STEMI (a less severe heart attack).
Research results show that the new cardiac magnetic resonance protocol has a sensitivity of 85 percent, a specificity of 96 percent and an overall accuracy of 93 percent, providing a new level of accuracy. Compared to a standard magnetic resonance protocol that carries an overall accuracy of 84 percent, the new protocol has the potential to significantly improve the diagnostic process.
According to Cury, it is clear that the new protocol provides a more accurate diagnosis of emergency room patients with chest pain, and he believes that the method is best used for patients with a moderate-likelihood of acute coronary syndrome, while cardiac CT may be used for patients with low-likelihood of acute coronary syndrome. Cury also explains that additional research is needed to determine how this new protocol could be integrated into emergency rooms and how it could truly change the triage process.
“These data suggest that a 30-minute CMR protocol is feasible and accurate in the emergency department setting. Future studies will need to determine the impact of CMR in clinical decision making and assess the cost-effectiveness of CMR in the emergency department setting," says Cury.
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