Three-dimensional 123I-meta-iodobenzylguanidine cardiac innervation maps to assess substrate and successful ablation sites for ventricular tachycardia: feasibility study for a novel paradigm of innervation imaging.
BACKGROUND
Innervation is a critical component of arrhythmogenesis and may present an important trigger/substrate modifier not used in current ventricular tachycardia (VT) ablation strategies.


METHODS AND RESULTS
Fifteen patients referred for ischemic VT ablation underwent preprocedural cardiac (123)I- meta-iodobenzylguanidine ((123)I-mIBG) imaging, which was used to create 3-dimensional (3D) innervation models and registered to high-density voltage maps. 3D (123)I-mIBG innervation maps demonstrated areas of complete denervation and (123)I-mIBG transition zone in all patients, which corresponded to 0% to 31% and 32% to 52% uptake. (123)I-mIBG denervated areas were ≈2.5-fold larger than bipolar voltage-defined scar (median, 24.6% [Q1-Q3, 18.3%-34.4%] versus 10.6% [Q1-Q3, 3.9%-16.4%]; P<0.001) and included the inferior wall in all patients, with no difference in the transition/border zone (11.4% [Q1-Q3, 9.5%-13.2%] versus 16.6% [Q1-Q3, 12.0%-18.8%]; P=0.07). Bipolar/unipolar voltages varied widely within areas of denervation (0.8 mV [Q1-Q3, 0.3-1.7 mV] and 4.0 mV [Q1-Q3, 2.9-5.6 mV]) and (123)I-mIBG transition zones (0.8 mV [Q1-Q3, 0.4-1.8 mV] and 4.6 mV [Q1-Q3, 3.2-6.3 mV]). Bipolar voltages in denervated areas and (123)I-mIBG transition zones were <0.5 mV, 0.5 to 1.5 mV, and >1.5 mV in 35%, 36%, and 29%, as well as 35%, 35%, and 30%, respectively (P>0.05). Successful ablation sites were within bipolar voltage-defined scar (7%), border zone (57%), and areas of normal voltage (36%), but all ablation sites were abnormally innervated (denervation/(123)I-mIBG transition zone in 50% each).


CONCLUSIONS
(123)I-mIBG innervation defects are larger than bipolar voltage-defined scar and cannot be detected with standard voltage criteria. Thirty-six percent of successful VT ablation sites demonstrated normal voltages (>1.5 mV), but all ablation sites were within the areas of abnormal innervation. (123)I-mIBG innervation maps may provide critical information about triggers/substrate modifiers and could improve understanding of VT substrate and facilitate VT ablation.


CLINICAL TRIAL REGISTRATION
URL: http://www.clinicaltrials.gov. Unique Identifier: NCT01250912.
['Klein|Thomas|T|', 'Abdulghani|Mohammed|M|', 'Smith|Mark|M|', 'Huang|Rui|R|', 'Asoglu|Ramazan|R|', 'Remo|Benjamin F|BF|', 'Turgeman|Aharon|A|', 'Mesubi|Olurotimi|O|', 'Sidhu|Sunjeet|S|', 'Synowski|Stephen|S|', 'Saliaris|Anastasios|A|', 'See|Vincent|V|', 'Shorofsky|Stephen|S|', 'Chen|Wengen|W|', 'Dilsizian|Vasken|V|', 'Dickfeld|Timm|T|']
D019797:3-Iodobenzylguanidine D000200:Action Potentials D000368:Aged D000465:Algorithms D015142:Baltimore D017115:Catheter Ablation D022062:Electrophysiologic Techniques, Cardiac D005240:Feasibility Studies D005260:Female D006352:Heart Ventricles D006801:Humans D007090:Image Interpretation, Computer-Assisted D021621:Imaging, Three-Dimensional D008297:Male D008875:Middle Aged D011237:Predictive Value of Tests D011446:Prospective Studies D011877:Radionuclide Imaging D019275:Radiopharmaceuticals D013564:Sympathetic Nervous System D017180:Tachycardia, Ventricular D016896:Treatment Outcome
innervation cardiac imaging techniques tachycardia, ventricular