Association of regional myocardial conduction velocity with the distribution of hypoattenuation on contrast-enhanced perfusion computed tomography in patients with postinfarct ventricular tachycardia

BACKGROUND Cardiac magnetic resonance imaging has been shown to be beneficial for identification of the ventricular tachycardia (VT) substrate before catheter ablation. Contrast-enhanced perfusion multidetector computed tomography (CEP-MDCT) is more generalizable to clinical practice, and wall thickness and regional hypoenhancement on CEP-MDCT can identify potential substrate sites, albeit with decreased specificity. OBJECTIVE The purpose of this study was to evaluate the association between wall thickness and attenuation on CEP-MDCT with local conduction velocity (CV) and electrogram abnormalities in patients with postinfarct VT. METHODS Fourteen patients with postinfarct VT underwent preprocedural CEP-MDCT followed by endocardial electroanatomic mapping (EAM) and ablation. Myocardial attenuation and wall thickness were calculated from 3-dimensional MDCT images using ADAS-VT software (Galgo Medical). EAM was registered with 3-dimensional MDCT images using the CartoMERGE module of CARTO3 software (Biosense Webster). Local CV was calculated by averaging the velocity between each point and 5 adjacent points with concordant wavefront direction. RESULTS A total of 3689 points were included. In multivariable regression analysis clustered by patient, local CV was positively associated with myocardial attenuation, bipolar voltage, unipolar voltage, and wall thickness. Each 10-HU drop in full- thickness attenuation correlated to 2.6% decrease in CV (P <.001) and 5.5% decrease in bipolar voltage amplitude (P <.001), after adjusting for wall thickness. CONCLUSION Myocardial attenuation distribution on CEP-MDCT is associated with regional CV and electrogram amplitude. Regions with low CV identified with low attenuation on CEP-MDCT may serve as important VT substrates in postinfarct patients.