Temporal trends in pretest probability and normal scan rates in myocardial perfusion imaging: a 24-year experience from a Swiss tertiary referral center (between 2000 and 2024).

Myocardial perfusion imaging (MPI) is widely used to assess coronary artery disease (CAD). U.S. studies have reported increasing normal MPI findings over time. However, European data are limited. This study examined temporal trends in pre-test probability (PTP) and MPI findings at a large Swiss centre. In this retrospective study, 45 686 MPI scans were analysed. Clinical data included demographics, symptoms, risk factors, MPI results, and coronary artery calcium score (CACS). Endpoints were defined as abnormal MPI (Summed Stress Score ≥4), small ischaemia (Summed Difference Score ≥2), and relevant ischaemia (≥10% ischaemia). PTP was calculated using the 2013/2019 ESC chronic coronary syndrome (CCS) guidelines, and risk factor-weighted clinical likelihood (RF-CL) from the 2024 guidelines. Normal MPI results increased significantly over time (53% (2000) → 66% (2024), P < 0.001), irrespective of unchanged PTP/RF-CL, modality, type of stress, symptoms and risk factors. Small ischaemia decreased (37.6% → 34.2%), while relevant ischaemia increased (11.0% → 13.2%, P < 0.001 each) slightly. SSS and SRS decreased significantly, whereas SDS remained unchanged. CACS and the prevalence of zero CACS remained unchanged over time. ESC PTP models overestimated the prevalence of abnormal MPI and small ischaemia. Only RF-CL predicted relevant ischaemia correctly in very low-risk patients. The rate of normal MPI results increased over time, but the trend was less pronounced than previously published. Possible explanations include referral of healthier patients (unchanged CACS despite increasing age), less typical angina, a lower prevalence of established CAD, and more female patients.