116 Contractility reserve in segments non-viable on delayed enhancement; analysis with low dose dobutamine MRI

Background

Transmural extent of infarction (TEI) of >50% on delayed enhancement (DE) images is considered as non-viable and as a result not revascularised.

Purpose

To investigate the contractility reserve before revascularisation of a chronic total coronary occlusion (CTO).

Methods and materials

Dobutamine stress leads to an increase in systolic wall thickening in viable tissue. Forty-seven patients with a CTO of a coronary artery were included. Segmental wall thickening (SWT) at rest and during dobutamine stress (5 and 10 microg/kg/min) were evaluated. DE-images were performed to calculate the TEI. Segments were scored as dysfunctional if SWT was <45%.

Results

Seventy percent (151/216) of the segments in patients with a CTO were dysfunctional. Mean SWT of all CTO perfused segments was 35% ± 34% which was significantly lower compared to remote segments; 52 ± 48% (p < 0.001). Dysfunctional segments with a TEI<50% showed a significant improvement in SWT with 5 microg/kg/min dobutamine. Interestingly segments with TEI 50%–75% showed a significant improvement in SWT were a higher dose was used (Figure 1).

Figure 1

All dysfunctional CTO segments. Contractility reserve in segments non-viable on delayed enhancement; analysis with low dose dobutamine MRI. This was observed as an increase in segmental wall thickening in segments with TEI<50% and 50%–75% although a higher dose was needed when TEI 50%–75%.

Conclusion

Contractility reserve is present in segments with TEI<50% and 50%–75% although a higher dose was needed when TEI 50%–75%.