Rate-Dependent Pacemap Matching in Scar-Related Ventricular Tachycardia: Impact of "TR Fusion" Phenomenon.

Background: The impact of varying rates of pacemapping (PM) rates on QRS morphology and PM score matching in patients with scar-related ventricular tachycardia (VT) has not been systematically assessed.

Objectives: In this study, the authors sought to assess the variability in PM score matching at different pacing rates.

Methods: During substrate mapping for VT ablation, PM was performed at cycle lengths (CLs) of 600 ms, 500 ms, 400 ms, 300 ms, and VT CL.

Analysis of stress-only imaging, comparing upright and supine CZT camera acquisition to conventional gamma camera images with and without attenuation correction, with coronary angiography as a reference.

Background: Diagnostic performance of stress-only imaging using a Cadmium-Zinc-Telluride (CZT) camera has not been directly compared in the same patients to stress-only attenuation-corrected conventional Anger camera images.

Methods: 112 subjects with correlative coronary angiographic data and 40 subjects with <5% pre-test likelihood of coronary disease completed attenuation-corrected stress-only images on a conventional Anger camera and uncorrected upright and supine stress images on a CZT camera. Two readers provided independent, blinded interpretations of stress-only images.

Computer derived transient ischemic dilation ratio for identifying extensive coronary artery disease using a CZT camera and imaging in the upright position.

Background: Transient ischemic dilation (TID) of the left ventricle (LV) has not been validated as a marker of extensive coronary artery disease (CAD) for studies using a cadmium-zinc-telluride (CZT) camera with upright imaging.

Methods: TID ratios were obtained from upright stress and rest images on a CZT camera. Separate cut-off values were determined for exercise and for regadenoson stress.