Cardiovascular (CV) imaging has become the focus of numerous efforts on the part of public and private payers to constrain further growth in utilization of noninvasive services. The purpose of this brief report is to review the growth of CV imaging, detail recent changes in patterns of growth, discuss possible underlying reasons, and anticipate appropriate responses. This brief report will be one of our periodic reviews detailing important trends in CV imaging services.

The U.S. has experienced significant growth in national health expenditures, averaging 4.8% per year from 1960 to 2006 (1). Today, much of the growth in spending is not only related to coronary heart disease but to most chronic conditions including diabetes, arthritis, hypertension, and kidney disease (2). The growth in spending for imaging parallels an increase in spending for chronic conditions including payments to orthopedic surgeons, radiologists, and cardiologists, to name a few (2). As is illustrated in (Figure 1), payments for imaging services to cardiologists represent a small proportion of payments for all of imaging and reflects the diverse needs of the Medicare population (3). In the year 2000, the total payment to cardiologists was $1.6 billion and increased by more than 200% to $5.1 billion in 2006. In 2006, only 36% of total Medicare Part B revenues were paid to cardiologists for in-office imaging services (3). This payment to cardiologists for imaging services represents 8.7% of total payments for all physician services in 2006 (4). When including estimates of payments by private health insurance, the total expenditures related to CV imaging are estimated to approach $17 billion (5).

CV imaging procedures are commonly listed within the leading 200 Medicare expenditures. (Figures 2, 3) plot the trends of leading Medicare charges for current procedural codes for myocardial perfusion single-photon emission computed tomography (SPECT), echocardiography, exercise testing (without imaging), and cardiac catheterization (6). The growth in the utilization of echocardiography and myocardial perfusion SPECT was substantially higher than that reported for exercise testing (without imaging) and for left heart catheterization.

Advanced imaging techniques, such as cardiovascular magnetic resonance, positron emission tomography, and cardiac computed tomography (CT) have not realized the growth in imaging utilization to the same extent as echocardiography and nuclear cardiology (Figure 4) (7). Of the 3 procedures, cardiac CT has experienced the greatest growth. From 2000 to 2005, the utilization grew from 0.31 to 1.21 CT procedures performed for every 1,000 Medicare patients. A more detailed description of specific utilization by CT codes noted a modicum of growth for these procedures (data provided by the Society of Cardiovascular CT) (Table 1). Substantive growth in utilization with CT is quite possible in the next decade.

The trends in increasing utilization were commented on in Government Accounting Office reports as early as 2002, and culminated in a detailed evaluation of spending growth in all of imaging services in 2008 (6). In fact, the high annual growth rates for both echocardiography and myocardial perfusion SPECT have attenuated after 2005 (Figure 2) (3).

Following a roundtable discussion, the editors of JACC: Cardiovascular Imaging put forth several important considerations on the growth of imaging that focus on the concern over misinterpretation as solely overuse of testing services. At first glance, a review of the data that highlights the growth in CV imaging must also be placed within the context of total growth in imaging services including that of radiology, vascular surgery, orthopedic surgery, primary care, and urology. Throughout the years, Medicare payments for part B services to cardiologists have represented nearly one-fifth to one-third of all imaging payments (Figure 1). The underlying rationale for imaging utilization remains ill defined, yet may be appropriate or related to clinical or health care system causes. The question remains as to whether hidden trends exist within imaging utilization that may have precipitated growth within the outpatient sector.

To answer this question, we reviewed a recent analysis of the change in the source of Medicare spending, which revealed interesting temporal changes (2). Over the last few decades, a large proportion of coronary heart disease spending shifted from inpatient hospitalizations to the outpatient setting (Table 2). From 1997 to 2006, there was a 764.7% decline in spending for inpatient care, coinciding with a 108.8% and 217.6% increase in expenditures for outpatient and also from referring physicians. Should this represent “true” cost shifting where, in lieu of hospitalization, many patients are now cared for in the outpatient setting with imaging playing a gatekeeper role in the decision to hospitalize. If true, this pattern of care could partly explain recent trends in imaging growth. As clinicians working within CV medicine, many clinical examples of these changes can be recalled. Yet, this report provides an important consideration that now requires further investigation in order to define causality in imaging growth.

To form an accurate model of the sources for imaging growth, analyses are required to evaluate the contributory role of age and other disease-related factors in relation to nonclinical or financial considerations. A reasoned approach is required to employ such analyses; otherwise, imaging cuts will affect the quality of patient care. One example of an analysis that has yet to be delineated is a comparison of inpatient versus outpatient imaging growth, since there is no major incentive or referral bias for the cardiologist in the diagnosis-related groups–based hospital setting.

Critical to reform of our current system is the imperative to develop an imaging evidence base that justifies the cost of imaging based on the benefits of downstream decision making. What is desperately needed is more support for comparative effectiveness randomized trials of imaging-guided strategies to reliably guide healthcare coverage and medical necessity decisions. This is the optimal means to devise indications for testing and provide high-quality imaging-guided care.