Dysfunctional but viable myocardium

Ischemic heart disease assessed by MRI and SPECT

Martin Ugander, MD

Department of Clinical Sciences, Lund

Department of Clinical Physiology

Lund University

Supervisor: Håkan Arheden, MD, PhD

Clinical Physiology, Lund

Co-supervisor: Peter Cain, MBBS, PhD

Wesley Heart Clinic, Brisbane, AU

Funding:• Swedish Research Council• Swedish Heart Lung Foundation• Faculty of Medicine at Lund University• Region of Scania

Aim

• To further elucidate the pathophysiology of dysfunctional but viable myocardium in patients with ischemic heart disease.

Outline of Studies

• Study I - Method for quantitative MRI & SPECT

• Study II - Wall thickening vs. Infarct transmurality

• Study III - LVEF vs. Infarct size

• Study IV - Time course of perfusion & function

after revascularization

Study I

Quantitative polar representation of left ventricular myocardial perfusion, function and viability using SPECT and cardiac magnetic resonance: initial results

Cain PA, Ugander M, Palmer J, Carlsson M, Heiberg E, Arheden H.

Clin Physiol Funct Imag 2005 (25) 215-222

Background

• Clinical management of CAD involves complex assessment of the extent and severity of changes in function, perfusion and viability.

• No adequate research tools for quantitative assessment exist.

Aims

• To explore the feasibility of integrative quantitative representation of LV perfusion, function and viability in polar plots.

• To determine agreement between visual scoring and quantitative measures.

Methods

• 10 patients scheduled for CABG– rest/stress SPECT– Cine and delayed enhancment CMR

• Quantification with in-house software

• Comparison with visual scoring using Kendall’s coefficient of concordance (W)

Methods

Results

Results

Kendall’s W: 1.0 (p<0.001) 0.85 (p<0.001)

Conclusions

• Side-by-side quantitative polar representation of LV perfusion, function and viability is feasible and may aid in the complex assessment of these parameters.

• The agreement between quantitative measurement and visual scoring was very good.

Study II

Infarct transmurality and adjacent segmental function as determinants of wall thickening in revascularized chronic ischemic heart disease

Ugander M, Cain PA, Perron A, Hedström E, Arheden H.

Clin Physiol Funct Imag 2005 (25) 209-214

Background

• Regional LV function in patients with IHD may be influenced by many factors.

Aims

• To explore how regional wall thickening in patients with chronic IHD is affected by both infarct transmurality and the function of adjacent segments.

• To compare with results from healthy subjects.

Methods

• 20 patients– 6 months after revascularization– Cine CMR– Delayed enhancement CMR

• 20 matched controls– Cine CMR

Multivariate analysis of parameters contributing to

wall thickening t p

Infarct transmurality -4.5 <0.001

Number dysf. adjacent seg. -22.9 <0.001

Conclusion

• The number of dysfunctional adjacent segments is a greater determinant than infarct transmurality on regional wall thickening.

• Infarction is difficult to assess by resting function alone.

• DE CMR is an important tool in this setting.

Study III

A maximum predicted left ventricular ejection fraction in relation to infarct size in patients with ischemic heart disease

Ugander M, Ekmehag B, Arheden H.

Submitted

Background

• An understanding of the relationship between LVEF and infarct size is important when assessing the potential benefit of revascularization in patients with IHD.

Aims

• To explore the relationship between LVEF and IS.

• To determine a maximum predicted LVEF for a given IS.

Methods

• 297 patients clinically referred for viability assessment by CMR

• LVEF

• Infarct size (% LVM)

Methods

Infarct size (%LVM)

LVE

F (

%)

A

θ BC

Patient characteristics (IHD)

Distribution of infarctions

Distribution of number of coronary artery vessel

territories

Results

Cine Contrast

LVEF=29% IS=36%

2ch

4ch

Cine Contrast

LVEF=25% IS=6%

2ch

4ch

Conclusions

• LVEF cannot be used to estimate IS.

• IS cannot be used to estimate LVEF.

• LVEF can be used to estimate a maximum predicted IS.

• IS can be used to estimate a maximum predicted LVEF.

Study IV

Influence of the presence of chronic non-transmural myocardial infarction on the time course of perfusion and functional recovery after revascularization.

Ugander M, Cain PA, Johnsson P, Palmer J, Arheden H.

Manuscript

Background

• The time course of recovery of LV function and perfusion after revascularization is not fully understood.

Aims

• To study the effect of presence of infarction on the time course of recovery of perfusion and function after elective revascularization.

Methods

• 15 patients (inclusion ongoing)– first time elective CABG (n=13) or PCI (n=2)

• Imaging– rest/stress SPECT– cine and delayed enhancement CMR– Before revasc., 1 & 6 months after revasc.

Patient characteristics

• 14 men, 1 woman

• mean age 68 years (range 52-84)

• 3VD n=6

• 2VD n=6

• 1VD n=3

• LVEF = 49 10%

Distribution of infarct transmuralities

Conclusions

• Dysfunctional segments without infarction improved both perfusion and function at 1 month.

• Segments with infarction showed improved perfusion at 1 month and improved function at 6 months.

• This may reflect more severe ischemic burden in segments with infarction.

Summary

• Study I - Method for quantitative MRI & SPECT

• Study II - Wall thickening vs Infarct transmurality

• Study III - LVEF vs Infarct size

• Study IV - Time course of perfusion & function

after CABG

Conclusion

• It is important to perform quantitative assessment of function,perfusion and viability in combination when studying the pathophysiology of dysfunctional but viable myocardium in IHD.

www.med.lu.se/cmr

Martin Ugander, MD, PhD-student

Ann-Helen Arvidsson, tech

Erik Hedström, PhD

Marcus Carlsson, MD, PhD-student

Christel Carlander, tech

Håkan Arheden, MD PhD

Karin Markenroth, PhD

Bo Hedén, MD PhDHenrik Engblom, MD, PhD-student

Einar Heiberg ,PhD

Henrik Mosén, MD, PhD

Erik Bergvall, MSc, PhD-student

The ischemic cascade

Mahrholdt et al2005 Eur Heart J