123 I-mIBG scintigraphy to predict inducibility of ventricular arrhythmias on cardiac electrophysiology testing: a prospective multicenter pilot study.
BACKGROUND
Disturbances of autonomic function after infarction are associated with both total mortality and sudden death. Although many imaging techniques for assessing the cardiac autonomic nervous system have been studied, the clinical usefulness of these techniques remains uncertain. This exploratory pilot study examined the relationship between abnormalities of ventricular sympathetic innervation delineated by scintigraphic imaging with (123)I-mIBG and inducible ventricular tachyarrhythmias in patients with left ventricular dysfunction and previous myocardial infarction.


RESULTS
Fifty patients underwent electrophysiological (EP) testing and 15-minute and 4-hour planar and single photon emission computed tomography (SPECT) imaging with (123)I-mIBG and SPECT imaging with (99m)Tc-tetrofosmin. The primary efficacy variables were the 4-hour heart:mediastinum ratio (H/M) and the (123)I-mIBG/(99m)Tc-tetrofosmin SPECT mismatch score. EP studies were categorized as positive (EP(+)) or negative (EP(-)) for inducibility of sustained (>30 seconds) ventricular tachyarrhythmias. Thirty patients were EP(+), and 20 were EP(-). There were no significant differences in the 4-hour H/M ratios or (123)I-mIBG/(99m)Tc-tetrofosmin SPECT mismatch scores between the two groups. In a multivariable analysis using all (123)I-mIBG and (99m)Tc-tetrofosmin SPECT measurements, the only variable that showed a significant difference between EP(+) and EP(-) patients was the 4-hour (123)I-mIBG SPECT defect score. A 4-hour (123)I-mIBG SPECT defect score of > or =37 yielded a sensitivity of 77% and specificity of 75% for predicting EP results.


CONCLUSIONS
The standard indices of (123)I-mIBG imaging (H/M and innervation-perfusion mismatch score) are not predictive of EP test results. The association of (123)I-mIBG SPECT defect severity with EP test inducibility in this exploratory study will require confirmation in a larger cohort of patients.
Bax
Jeroen J
JJ
Leiden University Medical Centre, Albinusdreef 2, Leiden, The Netherlands. j.j.bax@lumc.nl
Kraft
Otakar
O
Buxton
Alfred E
AE
Fjeld
Jan Gunnar
JG
Parízek
Petr
P
Agostini
Denis
D
Knuuti
Juhani
J
Flotats
Albert
A
Arrighi
James
J
Muxi
Africa
A
Alibelli
Marie-Jeanne
MJ
Banerjee
Gopa
G
Jacobson
Arnold F
AF
D019797:3-Iodobenzylguanidine; D000368:Aged; D001145:Arrhythmias, Cardiac / Q000503:physiopathology*; D001341:Autonomic Nervous System / Q000503:physiopathology*; D022062:Electrophysiologic Techniques, Cardiac; D005260:Female; D006321:Heart / Q000294:innervation*; D006801:Humans; D007457:Iodine Radioisotopes; D008297:Male; D008875:Middle Aged; D009203:Myocardial Infarction / Q000503:physiopathology; D009943:Organophosphorus Compounds; D015609:Organotechnetium Compounds; D049268:Positron-Emission Tomography; D019275:Radiopharmaceuticals; D013564:Sympathetic Nervous System / Q000503:physiopathology; D015899:Tomography, Emission-Computed, Single-Photon; D016277:Ventricular Function, Left
D007457:Iodine Radioisotopes; D009943:Organophosphorus Compounds; D015609:Organotechnetium Compounds; D019275:Radiopharmaceuticals; D019797:3-Iodobenzylguanidine; C078700:technetium tc-99m tetrofosmin