Does myocardial fibrosis hinder contractile function and perfusion in idiopathic dilated cardiomyopathy? PET and MR imaging study.
OBJECTIVE
To prospectively evaluate, by using positron emission tomography (PET) and magnetic resonance (MR) imaging, the interrelationships between regional myocardial fibrosis, perfusion, and contractile function in patients with idiopathic dilated cardiomyopathy (DCM).


METHODS
The study protocol was approved by the hospital ethics committee, and all subjects gave written informed consent. Sixteen patients with idiopathic DCM (mean age, 54 years +/- 11 [standard deviation]; nine men) and six healthy control subjects (mean age, 28 years +/- 2; five men) were examined with PET and MR tissue tagging. Oxygen 15-labeled water and carbon monoxide were used as tracers at PET to assess myocardial blood flow (MBF) and the perfusable tissue index (PTI), which is inversely related to fibrosis. MBF was determined at rest and during pharmacologically induced hyperemia. Maximum circumferential shortening (E(cc)) was determined with MR tissue tagging. Student t tests were performed for comparison of data sets, and linear regression was used to investigate the association between parameters.


RESULTS
Mean global hyperemic MBF (2.23 mL/min/mL +/- 0.73), E(cc) (-10.5% +/- 2.9), and PTI (0.95 +/- 0.10) were lower in the patients with DCM than in the control subjects (4.33 mL/min/mL +/- 0.85, -17.4% +/- 0.6, and 1.09 +/- 0.12, respectively; P < .05 for all). In the patients with DCM, regional PTI was related to E(cc) (r = -0.21, P = .009) but not to resting or hyperemic MBF. Furthermore, regional E(cc) was correlated to both resting (r = -0.28, P = .004) and hyperemic MBF (r = -0.29, P < .001). In addition, the ratio of left ventricular end-diastolic volume to mass, as a reflection of wall stress, was related to global hyperemic MBF (r = -0.52, P = .047) and to global E(cc) (r = 0.69, P = .003).


CONCLUSIONS
In idiopathic DCM, the extent of myocardial fibrosis is related to the impairment in contractile function, whereas fibrosis and perfusion do not seem to be interrelated. The degree of impairment of hyperemic myocardial perfusion is related to contractility and end-diastolic wall stress.
Knaapen
Paul
P
Department of Cardiology, VU University Medical Center, De Boelelaan 1117, Room 6D 120, 1081 HV Amsterdam, The Netherlands. p.knaapen@vumc.nl
Götte
Marco J W
MJ
Paulus
Walter J
WJ
Zwanenburg
Jaco J M
JJ
Dijkmans
Pieter A
PA
Boellaard
Ronald
R
Marcus
J Tim
JT
Twisk
Jos W R
JW
Visser
Cees A
CA
van Rossum
Albert C
AC
Lammertsma
Adriaan A
AA
Visser
Frans C
FC
D000328:Adult; D000368:Aged; D000704:Analysis of Variance; D002311:Cardiomyopathy, Dilated / Q000000981:diagnostic imaging* / Q000473:pathology* / Q000503:physiopathology; D016022:Case-Control Studies; D003287:Contrast Media; D003326:Coronary Circulation; D003331:Coronary Vessels / Q000000981:diagnostic imaging* / Q000473:pathology*; D005260:Female; D005355:Fibrosis / Q000000981:diagnostic imaging / Q000473:pathology / Q000503:physiopathology; D006801:Humans; D007090:Image Interpretation, Computer-Assisted; D008279:Magnetic Resonance Imaging; D008297:Male; D008875:Middle Aged; D009200:Myocardial Contraction / Q000502:physiology; D011446:Prospective Studies; D014055:Tomography, Emission-Computed
D003287:Contrast Media