Renal T1 Times on Cardiac Magnetic Resonance Reflect Renal Dysfunction and Are Associated with Adverse Outcomes: Insights from an All-Comer Cohort

<b>Background:</b> Renal disease is common in patients with cardiovascular disease (CVD) and is associated with adverse outcomes. Cardiac magnetic resonance (CMR) with advanced mapping techniques is the gold standard for characterizing myocardial tissue, and renal tissue is often visualized on these maps. However, it remains unclear whether renal T1 times accurately reflect renal dysfunction or predict adverse outcomes. <b>Aim:</b> To analyze the relationship between renal T1 times, renal dysfunction, and adverse outcomes. Adverse outcomes were defined as all-cause and cardiovascular death. <b>Methods:</b> Renal T1 times were measured in the native short-axis view in an all-comers cohort undergoing CMR. Renal function parameters were assessed at the time of CMR. <b>Results:</b> A total of 506 patients (mean age 60 ± 15 years, 53% male) were included in the analysis. A significant correlation was observed between log10 renal cortical T1 times and eGFR (r = -0.701, <i>p</i> < 0.001) and creatinine (r = 0.615, <i>p</i> < 0.001). Kaplan-Meier analysis showed an increased risk of all-cause (<i>p</i> < 0.001 by log-rank test) and cardiovascular mortality (<i>p</i> = 0.004 by log-rank test) in patients with renal cortical T1 times above the median. In the univariable Cox regression analysis, there was a significant association between renal cortical T1 times and increased risk of all-cause (HR = 1.73 [95% CI, 1.42-2.11] per every 100 ms increase <i>p</i> < 0.001) and cardiovascular mortality (HR = 1.41 [95% CI, 1.05-1.90] per every 100 ms increase, <i>p</i> = 0.021). This association remained statistically significant after adjustment for prespecified clinical factors (adjusted HR for all-cause death = 1.49 [95% CI, 1.10-2.02] per every 100 ms increase, <i>p</i> = 0.01; adjusted HR for cardiovascular death = 1.42 [95% CI, 1.05-1.90] per every 100 ms increase, <i>p</i> = 0.021). <b>Conclusions:</b> Our results indicate that there is a significant association between increased renal cortical T1 times and impaired renal function, as well as an increased risk of all-cause and cardiovascular mortality, although it should be noted that our results are preliminary and need to be validated in external cohorts performing renal biopsies.