Temporal trends in referral patterns for invasive coronary angiography - a multicenter 10-year analysis

Understanding how clinicians decide to refer patients for invasive coronary angiography is crucial for improving diagnostic accuracy and resource use. Prior research has shown that non-invasive tests are commonly used before invasive procedures. However, the effectiveness of these tests in identifying obstructive coronary artery disease remains unclear. This gap motivated a 10-year study to track how referral patterns evolved and how often these tests correctly identified significant disease. The study aimed to determine if diagnostic yield changed over time and whether newer tests improved outcomes. It also examined how often patients without prior non-invasive testing still underwent invasive procedures. These findings could help refine diagnostic pathways. The study focused on patients with suspected CAD who underwent elective ICA. It sought to clarify how referral practices changed over a decade and what impact this had on diagnostic yield.

The study aimed to evaluate how the use of non-invasive tests before invasive coronary angiography changed from 2008 to 2017. It also sought to determine the proportion of patients with obstructive coronary artery disease identified through these referrals. The specific problem addressed was the lack of clarity on whether referral patterns improved diagnostic accuracy over time. The motivation stemmed from the high rate of non-obstructive CAD found in patients referred for ICA. The researchers wanted to assess whether newer diagnostic tools like CCTA and stress CMR improved diagnostic yield. They also aimed to track trends in referral sources and their association with obstructive CAD. This information could guide better diagnostic strategies. The study focused on patients with suspected CAD undergoing elective ICA at two centers.

The study used a cross-sectional observational design across two centers from 2008 to 2017. It included 4805 consecutive patients with suspected coronary artery disease undergoing elective ICA. Researchers collected data on non-invasive testing prior to ICA and whether obstructive CAD was found. Obstructive CAD was defined as at least one lesion with ≥50% stenosis on ICA. The study compared patients with and without prior non-invasive testing. It also evaluated trends in diagnostic yield and referral sources over the 10-year period. The researchers analyzed how often patients underwent anatomical versus functional tests. They tracked changes in referral sources like SPECT, exercise ECG, CCTA, and stress CMR. The study also assessed whether revascularization rates varied by test type.

Of the 4805 patients, 84% had a positive non-invasive test before ICA, with SPECT and exercise ECG being the most common. Obstructive CAD was found in 54.5% of patients, and 37.9% underwent revascularization. Patients with prior non-invasive testing had a higher obstructive CAD rate (55.8%) compared to those without (48.1%). The proportion of obstructive CAD decreased over the study period (P < 0.001). Anatomical tests like CCTA were associated with higher obstructive CAD rates than functional tests (P = 0.001). Revascularization rates were also higher after anatomical testing (P = 0.018). Referrals after SPECT and exercise ECG declined (P = 0.005 and 0.006), while referrals after CCTA and stress CMR increased (P < 0.001). Nearly half of ICA patients did not have obstructive CAD, and this proportion increased over time.

The study found that nearly half of patients undergoing ICA for suspected CAD did not have obstructive lesions. This proportion increased over the 10-year period. The diagnostic yield of non-invasive tests varied, with anatomical tests like CCTA performing better than functional tests. Referral patterns shifted toward anatomical testing as SPECT and exercise ECG use declined. The authors suggest that better clinical assessment tools and diagnostic pathways are needed for stable CAD. They propose that current diagnostic strategies may not be optimizing resource use or diagnostic accuracy. The findings indicate a need for improved pre-ICA evaluation to reduce unnecessary procedures. The study highlights the importance of refining referral criteria and testing strategies. These conclusions are based on observed trends and diagnostic outcomes in the patient cohort.