External validation of novel clinical likelihood models to predict obstructive coronary artery disease and prognosis.

Objectives. The risk factor- and coronary artery calcium score-weighted clinical likelihood (RF-CL and CACS-CL respectively) models improve discrimination of patients with suspected obstructive coronary artery disease (CAD). However, external validation is warranted.
Compared to the 2019 European Society of Cardiology pre-test probability (ESC-PTP) model, the aims were 1) to validate the RF-CL and CACS-CL models for identification of obstructive CAD and revascularization, and 2) to investigate prognosis by CL thresholds.
Methods. Stable de novo chest pain patients (n=1,585) undergoing coronary computed tomography angiography (CTA) were investigated. Obstructive CAD was defined as >70% diameter stenosis in a major epicardial vessel on CTA. Decision of revascularization within 120 days was based on onsite judgment. The endpoint was non-fatal myocardial infarction or cardiovascular death. The ESC-PTP was calculated based on age, sex and symptom typicality, the RF-CL additionally included number of risk factors, and the CACS-CL incorporated CACS to the RF-CL.
Results. Obstructive CAD was present in 386/1,585 (24.4%) patients, and 91/1,585 (5.7%) patients underwent revascularization. Both the RF-CL and CACS-CL classified more patients to very-low CL (<5%) of obstructive CAD compared to the ESC-PTP model (41.4% and 52.2% vs. 19.2%, p<0.001). In very-low CL patients, obstructive CAD and revascularization prevalences (≤6% and <1%) remained similar combined with low event risk during 5.0 years follow-up.
Conclusion. In an external validation cohort, the novel RF-CL and CACS-CL models improves categorization to a very-low CL group with preserved prevalences of obstructive CAD, revascularization and favorable prognosis.
Keywords: coronary artery disease; chronic coronary syndrome; clinical likelihood; pre-test probability.