Optimizing resource consumption with pre-test probability and the acoustic-based rule-out CAD-score - insights from the FILTER-SCAD trial

Abstract Background/Introduction The FILTER-SCAD randomized controlled trial (1) combined a pre-test probability (PTP) with the FDA-cleared CAD-score to improve deferred testing in patients suspected of obstructive coronary artery disease (OCAD). However, adherence to the recommended diagnostic strategy in the trial was low, with less than 25% of patients deferred. Purpose To evaluate the impact of a PTP and CAD-score-based deferral strategy on diagnostic resource utilization and clinical outcomes. Methods We conducted an observational post hoc analysis including patients from the FILTER-SCAD trial intervention group. Deferred testing was recommended for patients with PTP ≤5% and/or CAD-score ≤20, indicating low risk of OCAD. PTP was based on sex, age, and angina characteristics according to ESC guidelines. CAD-score was obtained using a non-invasive acoustic device. We assessed the number of potentially deferred tests and clinical outcomes, including significant OCAD and major adverse cardiac events (MACE) if following recommendations. Results Among the 1002 patients included in the study’s intervention group (mean age 62±12 years, 44.3% male), PTP ≤5% was observed in 135 (13.5%) and CAD-score ≤20 in 374 (37.3%) patients. Diagnostic testing was frequent, even in patients with PTP ≤5%, of whom 43.7% underwent testing, with only one (0.7%) positive test result, no invasive coronary angiographies, and no MACE. Among patients with CAD-score ≤20, OCAD was rare (≤2.1%), revascularisation was infrequent (≤1.9%), and MACE was minimal (two non-fatal events, both in patients with PTP 15%). In contrast, 11.4% of higher PTP patients required revascularisation and 20 experienced a MACE. Deferral of testing in PTP ≤5% would reduce testing by 13.5% of patients. Adding CAD-score ≤20 to the patients with PTP5%, would increase the number of patients with a deferred testing strategy to 40.5% (Figure 1). Combining PTP and CAD-score would safely reduce the overall number of diagnostic tests (n=1043) by 26% (Figure 2). Conclusion A PTP- and CAD-score-based deferred testing strategy could safely reduce unnecessary testing in low-risk CCS patients, thus optimizing resource use without compromising patient outcomes.