Key trends in diagnostic heart testing: CT on the rise as some traditional techniques fall out of favor
The different techniques and technologies clinicians use to evaluate patients for cardiovascular disease (CVD) have changed significantly in recent years, according to a new analysis published in Circulation: Cardiovascular Imaging.[1] While some modalities are on the rise, others are being utilized much less now than ever before.
“Controversies exist regarding the optimal use of each testing modality,” wrote corresponding author Andrew J. Einstein, MD, PhD, a cardiologist and cardiac imager with Columbia University Irving Medical Center and NewYork-Presbyterian Hospital, and colleagues. “Furthermore, the recent COVID-19 pandemic has had a documented impact on cardiac testing. The long-term impact of these disruptions remains poorly understood. Demonstration of trends in cardiac testing allows for anticipating the shifting technological requirements of cardiovascular service lines, tailoring the educational offerings of cardiology fellowship training programs and understanding how real-world clinical practice reflects guidelines.”
Einstein et al. explored U.S. Centers for Medicare and Medicaid Services data from 2010 to 2022, charting a variety of trends in how clinicians performed diagnostic testing to evaluate Medicare patients for CVD.
Transthoracic echocardiography remains the most common testing modality
The authors found that transthoracic echocardiography (TTE) was the most utilized modality in both 2011 and 2022, accounting for 61.5% and 67.7%, respectively, of all diagnostic cardiac tests performed in those years.
The use of single-photon emission computed tomography myocardial perfusion imaging (SPECT MPI), meanwhile, dropped from 20.8% of all tests in 2011 to 12.9% in 2022. Invasive coronary angiography (ICA), stress echocardiography and exercise treadmill tests (ETT) also decreased in overall utilization over the course of the study, replaced my increased utilization for transesophageal echocardiography (TEE), coronary computed tomography angiography (CCTA), structural cardiac CT, coronary artery calcium scoring (CACS), cardiac magnetic resonance (CRM), cardiac positron emission tomography myocardial perfusion imaging (PET MPI) and stress CMR.
One telling sign of SPECT MPI’s decreased utilization is how it compares with other modalities over time. While the ratio of SPECT MPI to CCTA was 61:1 in 2011, for example, that ratio was 10:1 in 2022. PET MPI and stress CMR have also been used more and more as SPECT MPI has grown less and less common among care teams.
Changes before and after the start of the pandemic
The utilization of all testing techniques took a hit in 2019 and 2020 due to the pandemic; some of those techniques bounced back, but others did not.
For example, the use of CCTA, CACS, CMR, stress CMR and cardiac positron emission tomography (PET) all “recovered to and well exceeded 2019 levels” by 2022.
“Conversely, traditional functional testing modalities, overall nuclear imaging and ICA showed decreases in 2020 and 2022,” the authors wrote. “TTE and TEE use in 2022 had recovered from 2020 reductions, but were still used 15% and 16% less often than in 2019.”
Radiologists much more involved in cardiac care than in the past
When tracking how different healthcare specialties used these different modalities from 2010 to 2022, Einstein et al. found that the biggest change was seen in CACS utilization. While cardiologists performed 65% of CACS scans in 2010, they only performed 13% in 2022. A similar trend was seen in CCTA; cardiologists read 63% of CCTA exams in 2010, but just 36% in 2022. In both instances, increased utilization by radiologists was directly responsible.
When it came to fractional flow reserve CT (FFR-CT), however, utilization increased significantly for both cardiologists and radiologists in recent years, but the ratio has remained similar.
SPECT vs. PET
The decline of SPECT MPI has been matched by an increase in PET MPI.
“Despite limitations to its widespread availability, including high costs and challenges in access to PET radiopharmaceuticals, our findings show that the large gap in procedure volumes between SPECT and PET perfusion imaging in the United States is decreasing,” the authors wrote. “The emergence of novel 18F-based perfusion radiopharmaceuticals such as 18F-flurpiridaz, which have longer half-lives compared with current tracers and are expected to be available in unit dosing, will likely further expand access to PET MPI.”
SPECT MPI is still being used regularly, of course, and cardiologists appear to be reading more of these exams now than they did in the past. While they were responsible for 85% of all SPECT MPI exams in 2010, for instance, that number increased to 88% in 2022. A similar trend was seen in PET MPI.
Reviewing key takeaways
Looking over these data, the authors noted that traditional stress testing has grown out of favor with many U.S. clinicians, replaced in many instances with advanced functional testing modalities such as PET MPI.
Another one of the study’s biggest takeaways was the rise of cardiac CT.
“Throughout the past decade, CT-based cardiac tests exhibited some of the highest growth rates among all testing modalities,” the authors wrote. “This is consistent with the growing use of anatomic testing in clinical practice, which enables not just stenosis assessment but also characterization of atherosclerotic plaque features as well as the rise of CACS in CAD risk stratification and the growth of cardiac CT for structural heart disease assessment and procedure planning. Although its optimal role in clinical practice remains debated, our finding that CCTA exhibited one of the highest growth rates across the study period, with an increasing number of practitioners, suggests a growing appreciation of its use as an alternative to functional testing.”
The group concluded its in-depth analysis with some final thoughts about the current state of diagnostic testing in the United States.
“In the U.S. Medicare population, advanced functional imaging including PET MPI and stress CMR, is rapidly growing in use relative to SPECT MPI, consistent with increasing evidence of their superior diagnostic accuracy, shorter study times and lower or no radiation exposure,” the authors wrote. “Despite current U.S. guidelines granting a Class 1 level of recommendation to both functional and anatomic testing for CAD evaluation, with a preference toward the former in patients over 65 years of age, CCTA displayed one of the highest growth rates of all tests. SPECT MPI volumes were almost halved from 2011 to 2022 and displayed a faster rate of decline post-2019, while PET MPI grew at one of the largest rates of any other modality.”
Click here to read the full analysis.
Michael has more than 18 years of experience as a professional writer and editor. He has written at length about cardiology, radiology, artificial intelligence and other key healthcare topics.