Cost analysis favours SPECT over PET and CTA for evaluation of coronary artery disease: the SPARC study

There are many ways to perform noninvasive testing in patients with coronary artery disease (CAD), including myocar-dial perfusion imaging with single-photon emission computed tomography (SPECT), positron-emission tomography (PET), and coronary computed tomography angiography (CTA). Results from series of patients evaluated with single modalities have already been published by many researchers [1–3], but there are few head-to-head comparisons of the outcomes of alternative test strategies [4, 5]. Consequently, the comparative effectiveness of different noninvasive cardiac testing strategies has been difficult to assess. The recently published SPARC registry (Study of Myocardial Perfusion and Coronary Anatomy Imaging Roles in Coronary Artery Disease) in JACC by the group of DiCarli et al. (Stanford, CA, USA) was a multicentre study designed to collect standardised clinical data on patients undergoing CTA, PET, or SPECT [6]. The primary purpose of the SPARC study was to evaluate the economic outcomes of using CTA, PET, or SPECT to evaluate patients with suspected CAD. The authors used an observational registry of 1703 patients: 590 patients underwent CTA, 548 patients had PET and 565 patients SPECT for diagnosis of suspected CAD. Patients were followed for 2 years; documented resource use, medical costs for CAD, and clinical outcomes were assessed. The main findings were that costs were significantly lower for SPECT compared with CTA or PET in the evaluation of suspected CAD. SPECT was economically attractive compared with PET, whereas CTA was associated with higher costs and no significant difference in mortality compared with SPECT. More specifically, the authors observed that patients who underwent coronary CTA and PET experienced higher rates of subsequent invasive coronary arteriography (16 % and 15 %, respectively) as compared with patients who underwent SPECT (7 %). The mean total radiation was significantly higher for CTA (15.1 mSV) compared with SPECT (11.7 mSV), both for the initial tests (13 mSV vs. 11 mSV) and for follow-up tests and procedures (2.1 mSV vs. 0.7 mSV). Exposure from follow-up tests and procedures was higher after PET (2.0 mSV) than after SPECT (0.6 mSV). The findings in favour of SPECT are in line with a decision model by Garber and Solomon [7], who compared exercise treadmill testing, stress echocardiography, planar thallium imaging, SPECT, and PET imaging with a strategy of immediate invasive angiography. They found SPECT to be much more cost-effective than PET for noninvasive diagnosis, and SPECT to be a better option than immediate invasive coronary angiography. In terms of …