Correlation of coronary artery geometry with the complexity and severity of coronary atherosclerosis: rationale and design of the GEOMETRY-CTA study
Authors: Rampidis G , Kouskouras K , Rafailidis V , Kampaktsis PN , Giannopoulos A , Giannakoulas G , Prassopoulos P , Karvounis H 
Published: July 2021

Abstract

Funding Acknowledgements
Type of funding sources: Public grant(s) – EU funding. Main funding source(s): This research is co-financed by Greece and the European Union (European Social Fund-ESF) through the Operational Programme «Human Resources Development, Education and Lifelong Learning 2014-2020» in the context of the project “Correlation of coronary artery tree geometry and clinical parameters with the distribution, complexity and severity of coronary artery disease: a pilot study using multislice CT coronary angiography” (MIS 5047882)

Background
Development and progression of coronary atherosclerosis is complex and not yet fully understood. Accumulative evidence supports the notion that coronary artery disease (CAD) results from an interaction of systemic factors, such as dyslipidemia, with local hemodynamic factors that regulate the site-specific predilection of atherosclerosis, particularly low endothelial shear stress (ESS). Since low ESS develops in geometrically irregular regions of the coronary tree for a given arterial blood flow, geometrical factors affect atherosclerotic plaque distribution and vulnerability. However, the correlation of coronary geometric features with the complexity and severity of CAD has not been fully elucidated.

Purpose
GEOMETRY-CTA is a prospective, non-randomized, observational study that aims to investigate the correlation of coronary artery geometrical features with the complexity and severity of CAD using Coronary Computed Tomography Angiography (CCTA). The prognostic value of a CCTA-derived geometric risk score will also be assessed.

Methods
The study aims to recruit 100 consecutive patients with suspected CAD and low/intermediate pre-test probability. Coronary geometrical characteristics such as angulation of coronary bifurcations, tortuosity, coronary artery volume index (CAVi) and vessel-length will be assessed with multi-planar reformation and volume rendering techniques, and integrated into a single geometric risk score. The extent and vulnerability of plaque burden will be calculated using several anatomical scoring systems such as the Leiden CTA risk score, CT-SYNTAX score, and CT-adapted Gensini score. Patients will be prospectively followed for 12 months after enrollment.

Results
The primary objective of the study is to evaluate the correlation of the geometric risk score with CAD severity and plaque vulnerability. We also hypothesize that wider bifurcation angles and lower CAVi augmenting the atherosclerosis-prone environment and predict higher CAD extent and complexity.

Conclusion
The present study aims to introduce a quantitative, non-invasive imaging biomarker expressing CAD severity and investigate its prognostic value in regards to adverse cardiovascular events. The derived index will be available for incorporation in larger national prospective studies for further cardiovascular risk stratification.