LAUSR

Cardiovascular disease (CVD) is the leading cause of morbidity and mortality among patients with chronic kidney disease (CKD). Mortality from CVD progressively increases with worsening severity of CKD, despite adjustment for confounders. The prevalence of coronary artery disease (CAD) is more than two-fold greater among patients with CKD than those with normal kidney function. This is likely a result of a combination of traditional risk factors, such as diabetes and hypertension, and non-traditional risk factors, such as oxidative stress and chronic inflammation. Thus, patients with CKD more frequently undergo revascularization procedures. Among Medicare beneficiaries, patients with CKD have a higher prevalence of percutaneous coronary intervention and coronary artery bypass grafting. Expectedly, these patients have a lower adjusted survival probability when stratified by CKD stage. Therefore, clinicians have long attempted to risk stratify patients with kidney disease. Risk stratification based on clinical variables alone, such as the Framingham risk score, has shown poor predictive accuracy for cardiovascular events in this population. Therefore, although clinical variables are used as the first step in defining risk, further stratification is often based on noninvasive or invasive imaging. Stress single-photon emission computed tomography (SPECT) myocardial perfusion imaging (MPI) is the most commonly used non-invasive testing modality in patients with CKD. The sensitivity and specificity of MPI is lower in patients with CKD than the general population, which may impact the prognostic utility of MPI in this population. Although there is plethora of retrospective, single-center data demonstrating the prognostic utility of SPECT MPI, a few studies have failed to demonstrate statistically significant results. In this issue of the Journal, Cantoni, Green and colleagues performed an updated systematic review and a comprehensive meta-analysis looking at the prognostic significance of SPECT MPI in patients with kidney disease. They summarized data from 16 studies (11 stage IV–V, 3 stage III–V, and 2 stage I–V), encompassing a total of 7834 CKD patients undergoing either pharmacological or exercise stress testing. The summary effect size was quantitatively presented as hazard ratios (HR). Although only studies that had a sample size of [ 100 patients and reported adjusted or unadjusted HRs were included, the statistical analysis is sound and appropriate. The primary outcome was the occurrence of adverse events, including death, myocardial infarction (MI), late coronary revascularization, stroke, heart failure, or acute coronary syndrome. A secondary analysis was performed for hard events of cardiac death or MI. Expectedly, this meta-analysis affirmed the prognostic value of SPECT MPI in patients with CKD, with a pooled HR for adverse events of 2.02 (95% CI 1.68– 2.42). The pooled HR for hard events (cardiac death or MI) was 2.36 (95% CI 1.77–3.13). The meta-regression analysis showed an association between HR for adverse events and age, hypertension and smoking. Generally, meta-analyses are performed to analyze cumulative data from several studies and calculate a more precise pooled effect size, taking into account the heterogeneity between studies. In the present report, there was little doubt about the prognostic value of MPI in patients with CKD, as most individual studies reported statistically significant results. The rare exceptions of negative studies were generally Reprint requests: Rami Doukky, MD, MSc, MBA, FASNC, Division of Cardiology, Cook County Health, 1901 W. Harrison St., Suite 3620, Chicago, IL 60612; [email protected] J Nucl Cardiol 2022;29:155–7. 1071-3581/$34.00 Copyright 2021 American Society of Nuclear Cardiology.