Quantitative Perfusion

1339184 - Myocardial perfusion reserve assessed by quantitative CMR is lower in heart transplant patients than in healthy controls and is related to exercise capacity

Thursday, January 26, 2023

1:00 PM – 2:00 PM

Location: Pacific Jewel

Presenting Author(s)

Henrik Engblom, MD, PhD

Professor
Lund University
Lund, Skane Lan, Sweden

Primary Author(s)

KD

Kristian Dimovski, Medical doctor

medical doctor
Lund University, Sweden

Co-Author(s)

KS

Katarina Steding-Ehrenborg, PhD

Associate Professor
Lund University, Skane University Hospital
Lund, Skane Lan, Sweden
GG

Grunde Gjesdal

MD
Lund University, Sweden
RJ

Robert Jablonowski, MD, PhD

MD, PhD
Lund University
Lund, Sweden
HX

Hui Xue, PhD

Director, Imaging AI Program
National Institutes of Health
Bethesda, Maryland, United States
PK

Peter Kellman, PhD

Senior Scientist
National Institutes of Health, Maryland, United States
OB

Oscar Braun, MD, PhD

Associate Professor
Skåne University Hospital, Sweden
HA

Håkan Arheden, MD, PhD

Professor
Lund University
Lund, Sweden

Background: Heart transplant (HTx) patients have reduced exercise capacity compared to the general population. Furthermore, coronary microcirculation can be affected in transplanted hearts due to cardiac allograft vasculopathy (CAV). The possible connection between altered coronary microvascular function and variability in exercise capacity in HTx patients has been scarcely studied. The aim of this study was to evaluate microvascular function in HTx patients and healthy controls by quantitative cardiac magnetic resonance (CMR) perfusion mapping, and to relate microvascular function to objectively measured exercise capacity in HTx patients.

Methods: Twenty-nine HTx patients (51±15 years, 34% females) and 27 healthy controls (55±10 years, 37% females) underwent CMR. Quantitative short-axis perfusion maps (basal, mid, and apical) were acquired using single bolus (0.05 mmol/kg), dual sequence perfusion imaging¹ after 3 minutes of adenosine stress and at rest. Segments with regional hypoperfusion and late gadolinium enhancement-positive segments, either due to infarction or fibrosis, were removed before calculating global myocardial perfusion (MP). Myocardial perfusion reserve (MPR) was defined as the ratio between stress and rest MP. In addition, all patients underwent a maximum cardiopulmonary exercise test with gas-exchange analysis for objective determination of exercise capacity, including maximal workload, O₂ pulse, VO₂peak and VO₂ at the ventilatory anaerobic threshold (AT). Results are presented as mean ± standard deviation (SD). Mean values were compared using the unpaired t-test. The relationship between continuous variables was assessed with Pearson’s linear correlation coefficient.

Results: Heart transplant patients had lower stress MP (2.93 ± 0.76 vs 3.37 ± 0.77, p = 0.048) and MPR (2.72 ± 0.72 vs 3.74 ± 1.17, p < 0.001) compared to healthy controls (Figure 1). Furthermore, MPR in HTx patients was correlated with maximal workload, O₂ pulse, VO₂ peak and VO₂ at the AT (Figure 2). There was no significant difference in MP between female and male HTx patients (rest 1.17 ± 0.30 vs 1.04 ± 0.35, p = 0.37; stress 3.16 ± 0.74 vs 2.80 ± 0.76, p = 0.26).

Conclusion:

Microvascular function as assessed by quantitative CMR perfusion mapping is decreased in HTx patients compared to healthy controls. Furthermore, microvascular function is related to objective measures of exercise capacity in HTx patients.