Published on 02/03/2015 by admin
Filed under Internal Medicine
Last modified 02/03/2015
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Case 9
A 56-year-old woman with diabetes and a family history of coronary artery disease (CAD) was referred for exercise SPECT MPI for evaluation of exertional chest pain. The resting ECG was normal.
She exercised for 9:20 on a Bruce protocol, achieving an estimated workload of 10 METs. The peak heart rate was 144 beats/min (88% of maximum age-predicted heart rate). She described severe (9/10) chest pain at peak exercise, and there was greater than 1 mm ST depression at peak exercise. The blood pressure response was normal.
The SPECT images demonstrate a severe and extensive, partially reversible perfusion defect involving the anterior, anteroseptal, apical, and inferoapical regions. The perfusion pattern suggests proximal left anterior descending (LAD) disease.
In addition, the left ventricular cavity appears larger on poststress images compared to resting images. This finding (sometimes termed transient ischemic dilatation) is suggestive of extensive ischemia and is a marker of increased risk for future cardiac events. Note that the increased stress/rest LV cavity ratio (SRLVCR) is apparent on the vertical and horizontal long-axis images. Be wary of commenting on increased SRLVCR if the finding is only visually evident on the short-axis images. Misalignment of the short-axis slices may result in artifactual elevated SRLVCR. Misalignment of the long-axis slices will result in apparent increased SRLVCR on only half of the slices, while the reverse (decreased SRLVCR) will be evident on the other half of the slices.
When the tracer distribution is compared to a female-specific normal database, there is an extensive (46% of the left ventricle), partially reversible (26% of the defect) perfusion defect in the anterior, anteroseptal, apical, and inferoapical regions. The partial (rather than complete) defect reversibility is suggestive of infarction with residual (“border zone”) inducible ischemia.
Using a 50% reduction in resting regional 99m
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