Acoustic-based rule-out of stable coronary artery disease: the FILTER-SCAD trial

Abstract

Background and aims: Overtesting of low-risk patients with suspect chronic coronary syndrome (CCS) is widespread. The acoustic-based coronary artery disease (CAD)-score has superior rule-out capabilities when added to pre-test probability (PTP). FILTER-SCAD tested whether providing a CAD-score and PTP to cardiologists was superior to PTP alone in limiting testing.

Methods: At six Danish and Swedish outpatient clinics, patients with suspected new-onset CCS were randomized to either standard diagnostic examination (SDE) with PTP, or SDE plus CAD-score, and cardiologists provided with corresponding recommended diagnostic flowcharts. The primary endpoint was cumulative number of diagnostic tests at one year and key safety endpoint major adverse cardiac events (MACE).

Results: In total, 2008 patients (46% male, median age 63 years) were randomized from October 2019 to September 2022. When randomized to CAD-score (n = 1002), it was successfully measured in 94.5%. Overall, 13.5% had PTP ≤ 5%, and 39.5% had CAD-score ≤ 20. Testing was deferred in 22% with no differences in diagnostic tests between groups (P for superiority = .56). In the PTP ≤ 5% subgroup, the proportion with deferred testing increased from 28% to 52% (P < .001). Overall MACE was 2.4 per 100 person-years. Non-inferiority regarding safety was established, absolute risk difference 0.49% (95% confidence interval -1.96-0.97) (P for non-inferiority = .003). No differences were seen in angina-related health status or quality of life.

Conclusions: The implementation strategy of providing cardiologists with a CAD-score alongside SDE did not reduce testing overall but indicated a possible role in patients with low CCS likelihood. Further strategies are warranted to address resistance to modifying diagnostic pathways in this patient population.

Keywords: Chronic coronary syndrome; Coronary artery disease; Deferred testing; Diagnostic strategy; Heart sound; Implementation strategy; Pre-test probability; Risk stratification.

Graphical Abstract

Summary of the aim, methods and main findings of the FILTER-SCAD trial.

Figure 1

CONSORT diagram. Screening, randomization, and follow-up in the FILTER-SCAD trial

Figure 2

Cumulative no of diagnostic tests during follow-up, by allocated treatment group. Cumulative numbers of the primary endpoint diagnostic tests over time (weeks) for the SDE group and the SDE plus CAD score group. No differences were seen between the groups (1073 vs. 1042 diagnostic tests, P = .56)

Figure 3

Forest plot—subgroup analysis for the primary endpoint. Forest plot of stratifying variables (study site and PTP ≤ 5% vs. PTP > 5%) and pre-specified subgroup analysis of PTP, age, sex, hypertension, hyperlipidaemia, diabetes mellitus, smoking status, family history of premature CAD, and body mass index for the primary endpoint of cumulative numbers of diagnostic tests. P-values for interaction are unadjusted. PTP is estimated according to the 2019 European Society of Cardiology guidelines. CAD, coronary artery disease; PTP, pre-test probability

Figure 4

Key secondary composite endpoint of major adverse cardiac events (MACE). Probability of MACE over time (months) for the SDE group and the SDE plus CAD-score group. MACE includes all-cause death, non-fatal myocardial infarction, hospitalization for unstable angina pectoris, heart failure, or ischaemic stroke, and major complications from cardiovascular procedures adjudicated by a clinical event committee