Cardiac adrenergic nerve function in patients with cardiac syndrome X.
BACKGROUND
We previously found a severe impairment of cardiac uptake of I-metaiodobenzylguanidine (MIBG), an analogue of norepinephrine, on myocardial scintigraphy in a small group of patients with cardiac syndrome X (CSX), suggesting a dysfunction of cardiac adrenergic nerve fibres. In this study, we assessed the consistency of these previous findings in a larger group of these patients.


METHODS
Planar and single-photon emission computed tomography MIBG myocardial scintigraphy was performed in 40 CSX patients (58 +/- 7 years, 17 men). Cardiac MIBG uptake was measured by the heart/mediastinum ratio and by a single-photon emission computed tomography regional cardiac MIBG uptake defect score (higher values = lower uptake). As a control group, we studied 20 healthy individuals (56 +/- 6 years, nine men). An exercise stress Tc-SestaMIBI myocardial scintigraphy was performed in 34 CSX patients (85%).


RESULTS
Cardiac MIBG defects were observed in 30 patients (75%), with nine (22.5%) showing no cardiac MIBG uptake at all. Compared with controls, CSX patients showed a significantly lower heart/mediastinum ratio (1.70 +/- 0.35 vs. 2.1 +/- 0.22, P < 0.001) and a higher cardiac MIBG defect score (27 +/- 25 vs. 4.4 +/- 2.5, P < 0.001). No differences were found in lung MIBG uptake between the two groups. Reversible perfusion defects on stress myocardial scintigraphy were found in 17 out of 34 CSX patients (50%), all of whom also had abnormal cardiac MIBG uptake; cardiac MIBG uptake abnormalities were also present in nine of 17 patients with normal perfusion scintigraphic images. Cardiac MIBG uptake findings were similar in our first 12 patients and in the 28 patients studied subsequently.


CONCLUSIONS
Our data show a relevant impairment of cardiac MIBG uptake in patients with CSX, suggesting that functional abnormalities in cardiac adrenergic nerve function may play a significant role in the mechanisms responsible for the syndrome.
Di Monaco
Antonio
A
Istituto di Cardiologia, Università Cattolica del Sacro Cuore, Rome, Italy.
Bruno
Isabella
I
Calcagni
Maria Lucia
ML
Nerla
Roberto
R
Lamendola
Priscilla
P
Barone
Lucy
L
Scalone
Giancarla
G
Mollo
Roberto
R
Coviello
Ilaria
I
Bagnato
Antonio
A
Sestito
Alfonso
A
Giordano
Alessandro
A
Lanza
Gaetano A
GA
Crea
Filippo
F
D019797:3-Iodobenzylguanidine; D000320:Adrenergic Fibers; D000368:Aged; D016022:Case-Control Studies; D003326:Coronary Circulation; D005260:Female; D006321:Heart / Q000000981:diagnostic imaging / Q000294:innervation*; D006801:Humans; D008297:Male; D008833:Microcirculation; D017566:Microvascular Angina / Q000000981:diagnostic imaging / Q000503:physiopathology*; D008875:Middle Aged; D055414:Myocardial Perfusion Imaging / Q000379:methods; D011237:Predictive Value of Tests; D019275:Radiopharmaceuticals; D013564:Sympathetic Nervous System / Q000503:physiopathology*; D017256:Technetium Tc 99m Sestamibi; D015899:Tomography, Emission-Computed, Single-Photon
D019275:Radiopharmaceuticals; D019797:3-Iodobenzylguanidine; D017256:Technetium Tc 99m Sestamibi