Aims Heart failure with preserved ejection fraction (HFpEF) causes substantial morbidity and mortality. Importantly, atrial remodeling and atrial fibrillation is frequently observed in HFpEF. Sodium-glucose cotransporter 2 inhibitors (SGLT2i) have recently been shown to improve clinical outcomes in HFpEF, and post-hoc analyses suggest atrial antiarrhythmic effects. We tested if isolated human atrial cardiomyocytes from patients with HFpEF exhibit an increased Na influx, which is known to cause atrial arrhythmias, and if that is responsive to treatment with the SGTL2i empagliflozin. Methods and Results Cardiomyocytes were isolated from atrial biopsies of 124 patients (82 with HFpEF) undergoing elective cardiac surgery. Na influx was measured with the Na-dye Asante Natrium Green–2 AM (ANG-2). Compared to patients without heart failure (NF), Na influx was doubled in HFpEF patients (NF vs HFpEF: 0.21±0.02 vs 0.38±0.04 mmol/L/min (N=7 vs 18); p=0.0078). Moreover, late INa (measured via whole-cell patch clamp) was significantly increased in HFpEF compared to NF. Western blot and HDAC4 pulldown assay indicated a significant increase in CaMKII expression, CaMKII autophosphorylation, CaMKII activity, and CaMKII-dependent NaV1.5 phosphorylation in HFpEF compared to NF, whereas NaV1.5 protein and mRNA abundance remained unchanged. Consistently, increased Na influx was significantly reduced by treatment with the CaMKII inhibitor autocamtide-2 related inhibitory peptide (AIP), late INa inhibitor tetrodotoxin (TTX) but also with NHE1 inhibitor cariporide. Importantly, empagliflozin abolished both increased Na influx and late INa in HFpEF. Multivariate linear regression analysis, adjusting for important clinical confounders, revealed HFpEF to be an independent predictor for changes in Na handling in atrial cardiomyocytes. Conclusion We show for the first time increased Na influx in human atrial cardiomyocytes from HFpEF patients, partly due to increased late INa and enhanced NHE1-mediated Na influx. Empagliflozin inhibits Na influx and late INa, which could contribute to antiarrhythmic effects in patients with HFpEF.

中文翻译：

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恩格列净抑制 HFpEF 患者心房心肌细胞 Na 内流增加

目的 射血分数保留的心力衰竭 (HFpEF) 导致大量的发病率和死亡率。重要的是，心房重构和心房颤动在 HFpEF 中经常观察到。钠-葡萄糖协同转运蛋白 2 抑制剂 (SGLT2i) 最近被证明可以改善 HFpEF 的临床结果，事后分析表明具有房性抗心律失常作用。我们测试了从 HFpEF 患者分离的人心房心肌细胞是否表现出 Na 内流增加（已知这会导致房性心律失常），以及这是否对 SGTL2i 恩格列净治疗有反应。方法和结果 从 124 名接受择期心脏手术的患者（82 名 HFpEF）的心房活检中分离出心肌细胞。 Na 流入量使用 Na 染料 Asante Natrium Green–2 AM (ANG-2) 进行测量。与无心力衰竭 (NF) 的患者相比，HFpEF 患者的 Na 流入量增加了一倍（NF vs HFpEF：0.21±0.02 vs 0.38±0.04 mmol/L/min（N=7 vs 18）；p=0.0078）。此外，与 NF 相比，HFpEF 中的晚期 INa（通过全细胞膜片钳测量）显着增加。 Western blot 和 HDAC4 Pulldown 测定表明，与 NF 相比，HFpEF 中 CaMKII 表达、CaMKII 自磷酸化、CaMKII 活性和 CaMKII 依赖性 NaV1.5 磷酸化显着增加，而 NaV1.5 蛋白和 mRNA 丰度保持不变。一致地，使用 CaMKII 抑制剂 autocamtide-2 相关抑制肽 (AIP)、晚期 INa 抑制剂河豚毒素 (TTX) 以及 NHE1 抑制剂卡立泊利治疗显着减少了 Na 流入的增加。重要的是，恩格列净消除了 HFpEF 中增加的 Na 内流和晚期 INa。多元线性回归分析，调整重要的临床混杂因素，揭示 HFpEF 是心房心肌细胞 Na 处理变化的独立预测因子。结论 我们首次发现 HFpEF 患者的人心房心肌细胞中 Na 内流增加，部分原因是晚期 INa 增加和 NHE1 介导的 Na 内流增强。 Empagliflozin 抑制 Na 流入和晚期 INa，这可能有助于 HFpEF 患者的抗心律失常作用。