Abstract 3417: T2-Weighted Cardiovascular Magnetic Resonance Detects Acute Myocardial Ischemia Before the Onset of Irreversible Myocardial Injury
Background Specific detection of purely reversible ischemic myocyte injury early in the ischemic cascade has not been possible in vivo. T2-weighted cardiovascular magnetic resonance (CMR) is known to visualize the area at risk in myocardial infarction. However, no data are available for reversible ischemic injury, before the onset of necrosis.
Methods We studied seven dogs with serial T2-weighted and cine imaging at baseline, during transient coronary occlusion (25–35 minutes) and immediately after reperfusion in a 1.5 T MRI system. Late Gd enhancement (LGE) was used to assess irreversible injury. Myocardial water content was assessed using wet/dry weight measurements.
Results Systolic wall thickening was lost immediately after occlusion (baseline: 52Â±32%, occlusion: −18Â±16%; p<0.0001). In T2-weighted images the contrast to noise ratio between ischemic and remote myocardium increased progressively over time resulting with a transmural area of high T2 signal intensity 28Â±4 minutes after occlusion (CNR: 11.0Â±10; p<0.0001). This persisted after reperfusion (figure 1⇓). LGE performed after reperfusion did not show irreversible injury in any of the dogs. Myocardial water content was mildly elevated in ischemic compared to remote segments (65Â±7% vs. 63Â±7%; p=ns).
Conclusion We provide first evidence that T2-weighted CMR imaging detects acute myocardial ischemia before the onset of irreversible injury. T2-weighted CMR may provide a non-invasive biomarker for reversible myocyte injury in patients with acute coronary syndromes.