Subendocardial Ischemia In Patients with Chest Pain and Normal Coronary Angiograms: A Cardiovascular Magnetic Resonance Study
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July 5, 2007 By Caitlin J. Harrigan [1]
Amsterdam, NL: 20% of patients with anginal episodes have normal coronary angiograms. Microvascular obstruction or abnormal pain perception have been proposed to be the underlying mechanism for this condition (also known as 'Syndrome X'). Diagnostic studies such as PET, nuclear imaging and echocardiography have found abnormalities consistent with ischemia in patients with an otherwise normal angiogram. Investigators from the Netherlands report today on the use of cardiovascular magnetic resonance (CMR) imaging to demonstrate abnormalities in not just subendocardial but also subepicardial perfusion.
In the European Heart Journal, Vermeltfoort et. al from the VU University Medical Centre in Amsterdam report their findings in a cohort of 34 patients with typical chest pain and normal coronary angiograms. All patients had exterional angina and an abnormal EKG. All patients underwent coronary angiography and CMR imaging. Patients who underwent PTCA, CABG or had a previous MI were excluded. The mean time between the angiogram and CMR was 11.6 months.
Myocardial perfusion index (MPI) was quantified by plotting the maximum up-slopes of the myocardium and the left ventricular blood pool using five- and three- linear fits. The authors hypothesized that adenosine-induced perfusion dysfunction would be present in the subendocardium. However, the authors found that patients with classic chest pain and normal angiograms had microvascular dysfunction in both the subendocardium and the subepicardium.
The limitations of this study include its small size, the long duration of time between the angiogram and the CMR, and the presence of flow-related artifacts on the CMR scans. Further studies using a CMR sequence more sensitive to coronary flow, and a greater sample size are needed to determine if 'Syndrome x' involves dysfunction of both the subendocardial and the subepicardial microvasculature.
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