An analysis of Medicare Part B databases found that the use of radionuclide myocardial perfusion imaging (MPI), stress echocardiography and coronary CT angiography for suspected coronary artery disease declined in recent years.

Although studies have shown the value of coronary CT angiography, it is still being used much less frequently than the other two noninvasive imaging techniques.

Lead researcher David C. Levin, MD, of Thomas Jefferson University Hospital in Philadelphia, and colleagues published their results online in the Journal of the American College of Radiology on Jan. 16.

“We do not mean to imply that MPI and [stress echocardiography] have no value,” they wrote. “They are tests of cardiac function, whereas [coronary CT angiography] provides an assessment of coronary artery anatomy. As such, the two types of examinations complement each other. [Coronary CT angiography] does have its own drawbacks. In patients who are obese or have heavily calcified vessels, rapid heart rates, or arrhythmias, [coronary CT angiography] quality may be suboptimal. Nevertheless, we believe that in appropriate patients, [coronary CT angiography] is the best first imaging test when [coronary artery disease] is suspected.”

The researchers mentioned that noninvasive imaging helps diagnose cardiovascular disease, which is the leading cause of death in the world. They cited data that found 379,559 people in the U.S. died of coronary artery disease in 2010, while 620,000 people have new, nonfatal MIs, 295,000 have recurrent MIs and 150,000 have new, silent MIs each year.

For this study, the researchers analyzed data on procedure volume, allowed payments and other administrative information for fee-for-service Medicare Part B enrollees from 2001 to 2013.

The utilization rates for MPI increased from 63.4 per 1,000 in 2001 to 88 per 1,000 in 2006. During that time period, the researchers noted that private practice cardiologists bought nuclear cameras with the intention of increasing their revenue by doing more MPI exams. However, the rates for MPI steadily declined each year thereafter to 61.9 per 1,000 in 2013. The trend was similar for cardiologists and radiologists.

The rates for stress echocardiography were around 12 to 13 per 1,000 each year from 2001 to 2010. They then steadily decreased and reached 10.8 per 1,000 in 2013. The researchers mentioned radiologists have little involvement in stress echocardiography, which is almost always handled by cardiologists.

The researchers added that cardiologists in private offices typically perform MPI and stress echocardiography exams. The decline in those exams coincided with the closure of many private cardiology offices and the acquisitions of private cardiology offices by hospitals. At the same time, the Centers for Medicaid & Medicare Services implemented sharp reductions in reimbursement for MPI and echocardiography.

Other possible reasons for the decline in MPI and stress echocardiography include that physicians may have adhered to the American College of Radiology and American College of Cardiology cardiac imaging appropriateness criteria and patients with high deductible health plans may have skipped the exams because they were too expensive. In addition, the economy was weak during those years, while the incidence of coronary artery disease decreased, as well.

“The downtrends in these examinations are likely to be welcomed by payers and policymakers, although it is not clear whether reduced use will adversely affect patient care,” the researchers wrote.

The codes for coronary CT angiography were first available in 2006. That year, the utilization rate was 0.99 per 1,000. The rate was 2.1 per 1,000 in 2007, but it declined to 1.07 per 1,000 in 2012 and 2013. In 2007, the rates were 1.26 per 1,000 for cardiologists and 0.67 per 1,000 for radiologists. However, by 2013, the rates were similar between the specialists: 0.49 per 1,000 for cardiologists and 0.52 per 1,000 for radiologists.

“The overall lack of growth in [coronary CT angiography] seems to be due to several factors, including the high cost of multidetector CT scanners with the required special software, the labor-intensive nature of the procedure, frequent denials by insurance carriers, and relatively poor reimbursement,” the researchers said.

The researchers noted that Medicare payments in 2013 were $234 for stress echocardiography, $463 for coronary CT angiography and $502 for MPI.

Although MPI has “significant shortcomings” in evaluating patients with suspected coronary artery disease, there were 58 times as many MPI’s performance in 2013 compared with coronary CT angiography.