Number 10-02: Inducible myocardial ischemia by dobutamine CMR- Case 1
Case from: P McParland, B Hudson, J Shambrook, C Peebles, S Harden.
from Department of Cardiothoracic Radiology, Southampton University Hospital Trust, Southampton, UK
*** this is the first case of a series on dobutamine CMR. See also Case 10-05.
Clinical history: A 62 year old asthmatic male presented to his cardiologist with worsening atypical chest pain and breathlessness on exertion. He previously had a stent to the RCA in 1999. A non-invasive assessment of ischaemia was requested.
Given the history of asthma, this patient underwent a dobutamine CMR test. The SSFP short-axis cines of the left ventricle (Movie 1) were acquired at the base (top panel) and at the mid cavity levels(lower panel) at rest (first column), and during dobutamine infusion: 5 mcg/kg/min (second column), 10 mcg/kg/min (third column) and 15mcg/kg/min of dobutamine (fourth column). The images demonstrate an inducible wall motion abnormality in the inferolateral wall of the left ventricle extending from the base to the mid cavity.
In addition, a GRE first pass perfusion images (Movie 2) were acquired at peak stress (top panel) and at rest (lower panel). The basal and mid short axis images of the left ventricle during perfusion at maximum dobutamine stress demonstrates a perfusion abnormality of the inferolateral wall (hypoenhanced area).
Late gadolinium enhancement: the mid short axis post contrast images (Figure 1) reveals no late gadolinium enhancement.
In consideration of the CMR findings, the patient was referred for coronary angiography (Movie 3). This demonstrated and occluded RCA which filled via collaterals from the LAD. A PCI to the right coronary artery was successfully undertaken and the patient's symptoms resolved.
Perspective: This is a good example of an inducible motion wall abnormality and a perfusion defect in response to dobutamine stress. In this case the wall motion abnormality is subtle but definite, addition of first pass perfusion imaging at peak dobutamine stress increases the reporting confidence.
Editor's Comment: This case caused some debate among the 5 COTW reviewers. In particular, one reviewer felt that 15mcg/Kg/min is low dose to achieve a stress heart rate (85% age-predicted max) and therefore ischemia can be underestimated. The majority of the reviewers felt that at peak dobutamine infusion, perfusion images were easier to interpret than the cine images. There was a consensus that this is a nice example on the role of dobutamine CMR to assess inducible perfusion defect in addition to the presence of inducible wall motion abnormalities.
Authors' Reply: Whilst, we appreciate that a target heart rate would normally require a higher dobutamine level, this patient had a brisk response to dobutamine and achieved a target heart rate at this dose. In addition, a new inducible wall motion abnormality is an established end point for stopping a dobutamine stress test.
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2) Gebker R, Jahnke C, Manka R, Hamdan A, Schnackenburg B, Fleck E, Paetsch I. Additional value of myocardial perfusion imaging during dobutamine stress magnetic resonance for the assessment of coronary artery disease. Circ Cardiovasc Imaging. 2008 Sep;1(2):122-30.