Clinical variables and outcome
All patients were interviewed at enrollment in the prospective cohort study. Clinical parameters recorded were: age (years), sex (male/female), type of chest pain (atypical vs. typical), body mass index (BMI) (defined as weight/height2 in kg/m2), smoking status (past or current smoker, yes/no), hypertension (present/absent), dyslipidaemia (serum cholesterol >200 mg/dL or 5.18 mmol/L, present/absent), diabetes (plasma glucose ≥126 mg/dL or 7.0 mmol, present/absent) and family history of CAD (present/absent).
The CTCS was measured by the Agatston method [15] using dedicated software (syngo Calcium Scoring VE31H, Siemens, Germany). The outcome of interest was the presence of obstructive CAD defined as ≥50% stenosis in at least one vessel (present/absent) on CCA.