Effects of dabigatran versus warfarin on 2-year cognitive outcomes in old patients with atrial fibrillation: results from the GIRAF randomized clinical trial.

BACKGROUND: Observational studies support a role for oral anticoagulation to reduce the risk of dementia in atrial fibrillation patients, but conclusive data are lacking. Since dabigatran offers a more stable anticoagulation, we hypothesized it would reduce cognitive decline when compared to warfarin in old patients with atrial fibrillation. METHODS: The GIRAF trial was a 24-month, randomized, parallel-group, controlled, open-label, hypothesis generating trial. The trial was done in six centers including a geriatric care unit, secondary and tertiary care cardiology hospitals in São Paulo, Brazil. We included patients aged ≥ 70 years and CHA2DS2-VASc score > 1. The primary endpoint was the absolute difference in cognitive performance at 2 years. Patients were assigned 1:1 to take dabigatran (110 or 150 mg twice daily) or warfarin, controlled by INR and followed for 24 months. Patients were evaluated at baseline and at 2 years with a comprehensive and thorough cognitive evaluation protocol of tests for different cognitive domains including the Montreal Cognitive Assessment (MoCA), Mini-Mental State Exam (MMSE), a composite neuropsychological test battery (NTB), and computer-generated tests (CGNT). RESULTS: Between 2014 and 2019, 5523 participants were screened and 200 were assigned to dabigatran (N = 99) or warfarin (N = 101) treatment. After adjustment for age, log of years of education, and raw baseline score, the difference between the mean change from baseline in the dabigatran group minus warfarin group was - 0.12 for MMSE (95% confidence interval [CI] - 0.88 to 0.63; P = 0.75), 0.05 (95% CI - 0.07 to 0.18; P = 0.40) for NTB, - 0.15 (95% CI - 0.30 to 0.01; P = 0.06) for CGNT, and - 0.96 (95% CI - 1.80 to 0.13; P = 0.02) for MoCA, with higher values suggesting less cognitive decline in the warfarin group. CONCLUSIONS: For elderly patients with atrial fibrillation, and without cognitive compromise at baseline that did not have stroke and were adequately treated with warfarin (TTR of 70%) or dabigatran for 2 years, there was no statistical difference at 5% significance level in any of the cognitive outcomes after adjusting for multiple comparisons. TRIAL REGISTRATION: Cognitive Impairment Related to Atrial Fibrillation Prevention Trial (GIRAF), NCT01994265 .

Empagliflozin Inhibits Proximal Tubule NHE3 Activity, Preserves GFR, and Restores Euvolemia in Nondiabetic Rats with Induced Heart Failure.

BACKGROUND: SGLT2 inhibitors reduce the risk of heart failure (HF) mortality and morbidity, regardless of the presence or absence of diabetes, but the mechanisms underlying this benefit remain unclear. Experiments with nondiabetic HF rats tested the hypothesis that the SGLT2 inhibitor empagliflozin (EMPA) inhibits proximal tubule (PT) NHE3 activity and improves renal salt and water handling. METHODS: Male Wistar rats were subjected to myocardial infarction or sham operation. After 4 weeks, rats that developed HF and sham rats were treated with EMPA or untreated for an additional 4 weeks. Immunoblotting and quantitative RT-PCR evaluated SGLT2 and NHE3 expression. Stationary in vivo microperfusion measured PT NHE3 activity. RESULTS: EMPA-treated HF rats displayed lower serum B-type natriuretic peptide levels and lower right ventricle and lung weight to tibia length than untreated HF rats. Upon saline challenge, the diuretic and natriuretic responses of EMPA-treated HF rats were similar to those of sham rats and were higher than those of untreated HF rats. Additionally, EMPA treatment prevented GFR decline and renal atrophy in HF rats. PT NHE3 activity was higher in HF rats than in sham rats, whereas treatment with EMPA markedly reduced NHE3 activity. Unexpectedly, SGLT2 protein and mRNA abundance were upregulated in the PT of HF rats. CONCLUSIONS: Prevention of HF progression by EMPA is associated with reduced PT NHE3 activity, restoration of euvolemia, and preservation of renal mass. Moreover, dysregulation of PT SGLT2 may be involved in the pathophysiology of nondiabetic HF.

Cardioprotection conferred by sodium-glucose cotransporter 2 inhibitors: a renal proximal tubule perspective.

Sodium-glucose cotransporter 2 (SGLT2) inhibitors, also known as gliflozins, improve glycemia by suppressing glucose reuptake in the renal proximal tubule. Currently, SGLT2 inhibitors are primarily indicated as antidiabetic agents; however, their benefits extend far beyond glucose control. Cardiovascular outcome trials indicated that all studied SGLT2 inhibitors remarkably and consistently reduce cardiovascular mortality and hospitalization for heart failure (HF) in type 2 diabetes (T2D) patients. Nevertheless, the mechanisms underlying the unprecedented cardiovascular benefits of gliflozins remain elusive. Multiple processes that directly or indirectly improve myocardial performance may be involved, including the amelioration of proximal tubular dysfunction. Therefore, this paper provides a perspective on the potential cellular and molecular mechanisms of the proximal tubule that may, at least in part, mediate the cardioprotection conferred by SGLT2 inhibitors. Specifically, we focus on the effects of SGLT2 on extracellular volume homeostasis, including its plausible functional and physical association with the apical Na+/H+ exchanger isoform 3 as well as its complex and its possible bidirectional interactions with the intrarenal angiotensin system and renal sympathetic nervous system. We also discuss evidence supporting a potential benefit of gliflozins in reducing cardiovascular risk, attributable to their effect on proximal tubule handling of uric acid and albumin as well as in erythropoietin production. Unraveling the mechanisms behind the beneficial actions of SGLT2 inhibitors may not only contribute to a better understanding of the pathophysiology of cardiovascular diseases but also enable repurposing of gliflozins to improve the routine management of HF patients with or without T2D.