Pretransplant cardiac stress testing and transplant wait time in kidney transplantation candidates.

OBJECTIVE: Routine screening for cardiovascular disease before kidney transplantation remains controversial. This study aims to compare cardiac testing rates in patients with end-stage renal disease, referred and not referred for transplantation, and assess the impact of testing on transplant wait times. METHODS: This is a retrospective cohort study of 22 687 end-stage renal disease patients from 2011 to 2022, within an integrated health system. Cardiac testing patterns, and the association between cardiac testing and transplant wait times and post-transplant mortality were evaluated. RESULTS: Of 22 687 patients (median age 66 years, 41.1% female), 6.9% received kidney transplants, and 21.0% underwent evaluation. Compared with dialysis patients, transplant patients had a 5.6 times higher rate of stress nuclear myocardial perfusion imaging with single-photon emission (rate ratio (RR) 5.64, 95% CI 5.37 to 5.92), a 6.5 times higher rate of stress echocardiogram (RR 6.51, 95% CI 5.65 to 7.51) and 16% higher cardiac catheterisation (RR 1.16, 95% CI 1.06 to 1.27). In contrast, revascularisation rates were significantly lower in transplant patients (RR 0.46, 95% CI 0.36 to 0.58). Transplant wait times were longer for patients who underwent stress testing (median 474 days with no testing vs 1053 days with testing) and revascularisation (1796 days for percutaneous intervention and 2164 days for coronary artery bypass surgery). No significant association was observed with 1-year post-transplant mortality (adjusted OR 1.99, 95% CI 0.46 to 8.56). CONCLUSIONS: This study found a higher rate of cardiac testing in dialysis patients evaluated for kidney transplants. Cardiac testing was associated with longer transplant wait time, but no association was observed between testing and post-transplant mortality.

Prognostic Value of Stress Myocardial Perfusion Imaging Across the Spectrum of Cardiovascular Risk.

BACKGROUND: Single-photon emission computed tomography (SPECT) myocardial perfusion imaging (MPI) is widely used to identify ischemia. There is limited research to evaluate if there is a risk threshold below which SPECT-MPI may not add significant prognostic value. METHODS: Between January 1, 2012, and December 31, 2018, individuals who underwent SPECT-MPI were stratified into 4 risk groups. The primary outcome was acute myocardial infarction (MI) or death. Multivariable Cox proportional hazards regression analysis was used to calculated hazard ratios (HRs) with 95% confidence intervals (CIs). RESULTS: Among 48,845 patients (52.3% male, median age 67 years), 8.5% were low risk, 4.8% borderline risk, 18.1% intermediate risk, and 68.6% high risk based on the American College of Cardiology pooled cohort equation. Ischemia was more commonly detected in the high-risk cohort (19.4% in high-risk vs 6.5% in low-risk). SPECT-MPI testing was associated with a significantly increased use of preventive medications such as statin therapy, regardless of stress test results. At a median follow-up of 4.2 years, there was no significant association between ischemia and death or MI in the low-risk cohort (adjusted HR, 1.91; 95% CI, 0.94-3.92) or the borderline-risk cohort (adjusted HR, 1.58; 95% CI, 0.79-3.15). Ischemia was associated with a higher risk of death or MI in the intermediate-risk (adjusted HR, 1.57; 95% CI, 1.24-1.99) and high-risk groups (adjusted HR, 1.54; 95% CI, 1.44-1.64). CONCLUSIONS: SPECT-MPI was less useful for risk stratification among low-risk patients because of their low event rates regardless of test results.

Association between vehicle ownership and disparities in mortality after myocardial infarction.

Background: Access to reliable transportation is fundamental in the management of chronic disease. The purpose of this study was to investigate the association between vehicle ownership at the neighborhood-level and long-term mortality after myocardial infarction (MI). Methods: This is a retrospective observational study evaluating adult patients admitted for MI between January 1st, 2006, and December 31st, 2016. Neighborhoods were defined by census tract and household vehicle ownership data was obtained from the American Community Survey courtesy of the University of California, Los Angeles Center for Neighborhood Knowledge. Patients were divided into 2 groups: those living in neighborhoods with higher vehicle ownership, and those living in neighborhoods with lower vehicle ownership. The cutoff of 4.34% of households reporting not owning a vehicle was used to define a neighborhood as one with "higher" vs "lower" vehicle ownership as this was the median value for the cohort. The association between vehicle ownership and all-cause mortality after MI was assessed using Cox proportional hazards regression models. Results: A total of 30,126 patients were included (age 68.1 +/- 13.5 years, 63.2% male). After adjusting for age, sex, race/ethnicity, and medical comorbidities, lower vehicle ownership was associated with increased all-cause mortality after MI (hazard ratio [HR] 1.10; 95% confidence interval [CI] 1.06-1.14; p<0.001). This finding remained significant after adjusting for median household income (HR 1.06; 95% CI 1.02-1.10; p = 0.007). Upon comparison of White and Black patients living in neighborhoods with lower vehicle ownership; Black patients were found to have an increased all-cause mortality after MI (HR 1.21, 95% CI 1.13-1.30, p<0.001), a difference which remained significant after adjusting for income (HR 1.20; 95% CI 1.12-1.29; p<0.001). There was no significant difference in mortality between White and Black patients living in neighborhoods with higher vehicle ownership. Conclusion: Lower vehicle ownership was associated with increased mortality after MI. Black patients living in neighborhoods with lower vehicle ownership had a higher mortality after MI than White patients living in similar neighborhoods but Black patients living in neighborhoods with higher vehicle ownership had no worse mortality than their White counterparts. This study highlights the importance of transportation in determining health status after MI.

Testing the iron hypothesis in a mouse model of atherosclerosis.

Hepcidin, the iron-regulatory hormone and acute phase reactant, is proposed to contribute to the pathogenesis of atherosclerosis by promoting iron accumulation in plaque macrophages, leading to increased oxidative stress and inflammation in the plaque (the "iron hypothesis"). Hepcidin and iron may thus represent modifiable risk factors in atherosclerosis. We measured hepcidin expression in Apoe(-/-) mice with varying diets and ages. To assess the role of macrophage iron in atherosclerosis, we generated Apoe(-/-) mice with macrophage-specific iron accumulation by introducing the ferroportin ffe mutation. Macrophage iron loading was also enhanced by intravenous iron injection. Contrary to the iron hypothesis, we found that hepatic hepcidin expression was not increased at any stage of the atherosclerosis progression in Apoe(-/-) or Apoe/ffe mice and that the atherosclerotic plaque size was not increased in mice with elevated macrophage iron. Our results strongly argue against any significant role of macrophage iron in atherosclerosis progression in mice.