Report from SCMR: Combined cardiac MR exam outshines TIMI
A comprehensive cardiac MR exam may be the noninvasive answer to determining whether a subset of patients needs to be referred for cardiac catheterization, according to research presented last week at the Society for Cardiovascular Magnetic Resonance annual meeting in Barcelona.
Cardiologists rely on various clinical and biochemical markers that are processed through mathematical algorithms to determine whether patients with suspected coronary artery disease should be referred for catheterization. Thrombolysis in myocardial infarction flow (TIMI) is widely used to answer this question for patients with non-ST elevation acute coronary syndromes.
Researchers from the U.K. suggest that a comprehensive cardiac MR exam is a better test for answering this everyday clinical question.
Dr. Sven Plein, a lecturer in radiology at Leeds General Infirmary, compared the accuracy of a comprehensive cardiac MR protocol and TIMI in a study of 68 patients with a clinical diagnosis of non-ST elevation acute coronary syndromes. Their status was based on the presence of chest pain and abnormal electrophysiology tests.
The cardiac MR protocol included first-pass rest and adenosine-stress perfusion, wall motion, and late enhancement MRI. Visual analysis of results took an average of 30 minutes. The clinician aimed to identify cases that involved greater than 70% coronary artery stenoses requiring subsequent revascularization.
All patients received follow-up x-ray angiography to confirm the findings. Sixteen were subsequently catheterized, and eight were referred for coronary artery angioplasty or bypass.
Although comprehensive cardiac MR and TIMI correctly identified the severity of CAD in 83% of the cases, cardiac MR was far more sensitive to the presence of disease (96.4% vs. 50%, p<0.05).
Further analysis suggested that even stripped-down versions of the cardiac MR protocol are better than the current gold standard, Plein said. In fact, perfusion and cardiac MR coronary analysis were two percentage points more sensitive than the combined test (98.2% vs. 96.4%.) Combined perfusion and wall motion was equivalent to the comprehensive test.
