Based on the provided references, "Cad" most commonly refers to Coronary Artery Disease. It can be obstructive or non-obstructive, and non-obstructive CAD is often caused by endothelial dysfunction at the microvascular level, such as in cardiac syndrome X and coronary slow flow syndrome [2]. CAD is a chronic inflammatory disease, and its progression can rapidly change the functional capacity of patients.

CAD-RADS (Coronary Artery Disease-Reporting and Data System) is a tool for standardizing coronary CTA reports. CAD-RADS classification, ranging from CAD-RADS 0 (absence of CAD) to CAD-RADS 5 (total occlusion of a coronary artery), can be used to predict the incidence of major adverse cardiovascular events (MACE) and all-cause mortality, guiding physicians in risk assessment and prognosis prediction [1,3]. A novel functional CAD-RADS integrated with coronary CT angiography-derived fractional flow reserve (FFRCT) has superior value over anatomical CAD-RADS in guiding therapeutic decisions and is an independent predictor for 1-year outcomes [4].

In conclusion, CAD is a significant health concern related to coronary artery-based chronic inflammation. The CAD-RADS system, especially the functional CAD-RADS, plays an important role in standardizing reports, guiding treatment, and predicting patient outcomes. Understanding CAD and related classification systems helps in better management and prevention of cardiovascular diseases.