Archived case 84 · Jan 14-Jan 21, 2011
Acute Transmural Myocardial Infarction with No-Reflow Zone
Acute Onset of Chest Pain
The question posed to readers
Describe the pertinent imaging findings. Be as specific as possible. What is your diagnosis?
Images
Diagnosis
Acute Transmural Myocardial Infarction with No-Reflow Zone
Radiologic Findings Selected Cardiac MRI images: Cine 4-chamber view SSFP (Fig. 1) shows a diminished ejection fraction calculated at 30% with left ventricular apical dyskinesis. Cine short-axis (Fig. 2) and 4-chamber (Fig. 3) SSFP 5-minute delayed contrast-enhanced images reveal transmural enhancement of the left ventricle extending from the apex to the mid-ventricular level with concomitant involvement of the inferior lateral wall and mid- and inferior septal wall. Dark foci of signal intensity are seen in the left ventricular apex surrounding by hyper-enhancing myocardium. Short-axis (Fig. 4-6), 4-chamber (Fig. 7), and 2-chamber (Fig. 8) PSIR images confirm the large area of left ventricular transmural myocardial delayed hyperenhancement. No thrombus is seen. Diagnosis: Acute Transmural Myocardial Infarction with No-Reflow Zone
Differential Diagnosis
None
Discussion
The vast majority of cases of transmural left ventricular myocardial enhancement are due to ischemic heart disease and myocardial infarction from atherosclerotic disease. On delayed contrast-enhanced cardiac MRI, there is near or complete full-thickness myocardial wall enhancement that correlates with a specific vascular territory. In this case, the left anterior descending coronary artery (LAD) or more specifically, a wrap-around LAD that extends over the left ventricular apex. This pattern of delayed enhancement is often associated with regional hypokinesis, akinesis or dyskinesis.
A “no-reflow zone” manifests on delayed enhancement imaging as a region of dark signal intensity surrounded by hyper-enhancing myocardium. The finding reflects impaired diffusion of gadolinium into the central core of the infarction and is caused by extensive microvascular obstruction (MVO) and endothelial microvascular destruction resulting in myocyte death. Contrast diffuses into the periphery of the infract resulting in hyperenhancement but is delayed in reaching the central core of the infarct. This finding is time-dependent, not only within an exam itself, but when the exam is performed relative to the timing of the infraction. With respect to the former, these areas of MVO will eventually “fill-in” on delayed-imaging if one waits sufficiently long enough. With respect to the latter, the no-reflow zone is typically seen during the first 6-weeks following the infraction. It is more conspicuous early on and becomes less so with time.
Treatment
- Delayed contrast-enhanced cardiac MRI is now widely accepted as a tool for assessing myocardial viability and in identifying those potential patients that may benefit from coronary artery revascularization
- If the region of enhancement involves >50% of the myocardial wall, the infarction is considered to be transmural; most such patients have little functional recovery if bypassed
Prognosis
- The presence of a “no-reflow zone” and microvascular obstruction (MVO) has been shown to correlate with a significantly increased risk of adverse outcomes from myocardial infarction including:
- Adverse remodeling
- Diminished systolic function
- Dysrhythmias
Selected Readings
- Cummings KW, Bhalla S, Javidan-Nejad C, et al. A Pattern-Based Approach to Assessment of Delayed Enhancement in Non-Ischemic Cardiomyopathy at MR Imaging. RadioGraphics 2009; 29:89-103.
- Grizzard JD, Judd RM, Kim RJ. Ischemic Heart Disease and Non-Ischemic Cardiomyopathies. In: Cardiovascular MRI in Practice: A Teaching File Approach. Springer-Verlag; London: 2008; 26-27; 97-98.
- Mahrholdt H, et al. Assessment of Myocardial Viability by Cardiovascular Magnetic Resonance Imaging. Eur Heart J. 2002; 23(8): 602-619.
- Wagner A, et al. MR Imaging of Myocardial Perfusion and Viability. Magn Reson Imaging Clin N Am. 2003; 11(1): 49-66.
Filed under: Radiology, Medicine/Pulmonary
Original case written by its authors at Virginia Commonwealth University and published at this address as part of a weekly teaching collection. Reproduced here as an archive.