Computed tomography as a predictive tool for ventricular tachycardia

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Abstract Background Sudden cardiac death is the main cause of mortality worldwide. It is often linked with ventricular tachycardia (VT). To prevent VT, high-risk patients are typically equipped with intracardiac defibrillators (ICDs). Currently, left ventricular ejection fraction (LVEF) is the standard for determining a patient's risk level. Objective We hypothesized that the use of imaging software analyzing cardiac CT-scans could enhance the detection of patients with an increased risk of VT. Methods and Results In this study, 132 patients with ischemic cardiomyopathy (average age 66.2±11.4 years, with an average LVEF of 36.6±10.3%), all with implanted cardiac devices, underwent CT scans. We developed software to automatically analyze the heart's wall tissue thickness, cardiac fat, and calcification levels (Figure.1.A). A viable cardiac wall thickness of less than 3mm typically indicates a ventricular wall predominantly composed of scar tissue with minimal viable tissue remaining. In contrast, a viable wall thickness of less than 5mm includes regions with more viable tissue and therfore represents the total scar. Over an average follow-up of 6.6 years (79.8 ± 30.5 months) via live telemedicine, we observed that patients with VT had a significant difference in wall thickness ratio (3mm/5mm; no VT 0.31±0.18 vs, VT 0.44±0.18, p<0.01)) and higher calcification (0.10±0.38ml vs. 0.47±1.57ml, p=0.039). The amount of cardiac fat did not significantly differ between the no VT and VT groups (1.14±1.38ml vs.1.21±1.01ml, p=0.771). Logistic regression determined a critical cutoff for wall thickness at a ratio of 0.3 for 3mm and 5mm thickness. Kaplan Meyer analysis contrasted this wall thickness ratio of 0.3 (figure.1.B) against the established LVEF threshold of 35% (figure.1.C) for predicting VT-free survival, revealing a notable disparity favoring wall thickness ratio (p<0.01) over LVEF (p=0.77). Conclusions The findings suggest that a higher proportion of regions of thin viable tissue or dense scar in the total scar is a more effective predictor of VT-free survival than LVEF, potentially improving the identification of patients at risk for sudden cardiac death.Figure. 1

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