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Study of Myocardial Perfusion and Coronary Anatomy Imaging Roles in CAD |
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Study of Myocardial Perfusion and Coronary Anatomy Imaging Roles in CAD (SPARC)
Protocol Summary
What is SPARC? SPARC is a prospective, open-label, multicenter, sequentially sampled, observational study to define the clinical value of stress perfusion (stress SPECT, stress PET), noninvasive angiography (CTA) and combined perfusion-anatomy (PET/CT) studies.
Why SPARC? Recent advances in cardiac imaging–the availability of cardiac stress PET, the maturation of cardiac CTA, and the development of hybrid imaging with PET-CT– have stirred excitement and interest in the cardiology community. Although these modalities are an exciting new addition to cardiologist’s diagnostic armamentarium, data are necessary not only for gaining clinical acceptance for this modality amongst practicing physicians, but also to justify reimbursement for these modalities amongst payers. SPARC addresses several distinct questions regarding the efficacy of modalities used in the evaluation of CAD. First, how does stress perfusion imaging with PET compare to that of SPECT, a widely available and extensively validated modality. Second, how does a strategy of perfusion imaging compare to a strategy of coronary angiography using CTA. Further, is there a role for hybrid imaging, such as PET-CT, versus single modality approaches in the evaluation of patients with known or suspected CAD. Finally, the impact of patients’ clinical characteristics (sex, age, diabetes mellitus, history of CAD, geographic location, type of practice, etc.) impact on the questions addressed above. As detailed below, these questions will be addressed with respect to several endpoints including resource utilization, incremental prognostic value and risk stratification.
What are SPARC’s specific objectives? Three main clinical outcomes will be assessed: Post-test resource utilization as assessed by referral rate to catheterization within 90-days of the index study; Incremental prognostic value and risk stratification for predicting cardiac death and myocardial infarction; Cost-effectiveness
To this end, SPARC is organized with two distinct specific objectives with important differences in patient population and endpoints.
Specific Aim 1: To evaluate the impact of stress perfusion imaging with SPECT or PET, CT Angiography, and hybrid PET-CT on post-test resource utilization. The primary endpoint of specific aim 1 is to compare the impact of combined myocardial perfusion-coronary anatomy data to that of perfusion only [stress SPECT, stress cardiac PET (without CTA)] and anatomy only (CTA alone) on post-test resource utilization, as measured by referral to cardiac catheterization within 90 days of index noninvasive testing, in patients without CAD. Secondary endpoints: to compare the diagnostic accuracy for detection of epicardial CAD of stress PET and hybrid PET-CT, stress SPECT, and CTA, as defined by coronary angiography; to compare the referral rate to revascularization within 90 days of cardiac catheterization.
Specific Aim 2: To compare the incremental prognostic value and risk stratification of stress perfusion imaging with SPECT or PET, CT coronary angiography, and combined perfusion-anatomy imaging approaches. The primary endpoint of specific aim 2 is to compare the incremental value of stress perfusion only (stress PET and stress SPECT), coronary anatomy only (CTA data), and combined perfusion-anatomy studies (PET+CTA and SPECT+CTA) over clinical, historical and stress test data for the prediction of cardiac death and nonfatal myocardial infarction. Secondary endpoints: to compare the incremental value of these noninvasive imaging approaches over clinical, historical and stress test data for the prediction of a composite endpoint including cardiac death, nonfatal myocardial infarction, late (>6 month from index study) referral to revascularization, or late (>6 month from index study) hospitalization for chest pain or heart failure; to compare the incremental value of these noninvasive imaging approaches over clinical, historical and stress test data for the prediction of all cause mortality. In addition, the ability of these modalities –together and separately– to risk stratify patients is a primary goal of specific aim 2.
Who is eligible to enroll in SPARC? SPARC will enroll approximately 3,700 patients with (N=1,240) and without (N=2,460) a history of CAD who are being referred for routine clinical studies to one of four noninvasive imaging arms (stress SPECT, stress PET or PET/CT, or CTA). There will be approximately 925 patients in each of the four imaging arms (see Figure below). Inclusion criteria Intermediate or high pretest likelihood of CAD (>0.25; as defined by ACC-AHA Stable Angina Guidelines) Willingness to sign written informed consent Exclusion criteria Low pretest likelihood of CAD (<0.25 as defined by ACC-AHA Stable Angina Guidelines) Major concomitant noncardiac disease, which in the opinion of the investigator will preclude the patient from participation in the follow-up in the study Any social condition/situation that, in the opinion of the investigator, would preclude follow-up during the course of the study
Statistical Power A population sample size of 3,700 (including 2,460 patients without prior CAD and 1,240 patients with known CAD) will have >90% power, for a two-sided test at α=0.01, to detect a 2% difference in the primary endpoints (90-day catheterization rate, and occurrence of cardiac death or nonfatal MI within 2 years of the index noninvasive test) across imaging arms.
Figure. Integrated Study Populations in SPARC |