Serum Potassium and Mortality in High-Risk Patients: SPRINT

Association between the preprocedural serum potassium level and atrial fibrillation recurrence after catheter ablation

BACKGROUND

The association between serum potassium and atrial fibrillation (AF) recurrence after catheter ablation remains unclear.

OBJECTIVE

The purpose of this study was to investigate whether preprocedural serum potassium influences AF recurrence in patients who underwent catheter ablation.

METHODS

We used data of patients with AF who underwent de novo catheter ablation from the prospective Chinese Atrial Fibrillation Registry Study. Patients with prior ablation and without baseline serum potassium were excluded. The primary outcome was 1-year AF recurrence after a 3-month blanking period from the ablation procedure. Restricted cubic spline and Cox proportional models were used to compare outcomes across serum potassium categories.

RESULTS

A total of 4838 patients with AF who underwent de novo catheter ablation was enrolled. At 1 year, AF recurrence occurred in 1347 patients (27.8%). The relationship between preprocedural serum potassium and 1-year AF recurrence after ablation presented as U shape (P for nonlinear = .048). Compared with the group of serum potassium within 4.41-4.60 mmol/L, the risk of AF recurrence increased significantly in the lowest serum potassium group (≤4.00 mmol/L) after multivariate analysis (hazard ratio [HR] 1.26; 95% confidence interval 1.06-1.51; P = .010). Other categories with lower or higher serum potassium levels including 4.01-4.20 mmol/L (HR 1.18), 4.21-4.40 mmol/L (HR 1.16), 4.61-4.80 mmol/L (HR 1.07), and ≥4.81 mmol/L (HR 1.11) showed nonsignificant higher recurrence risk.

CONCLUSION

The relationship between preprocedural potassium and AF recurrence was U shaped, with an optimal potassium range (4.41-4.60 mmol/L). Lower potassium level is associated with increased AF recurrence risk after catheter ablation.

Microfluidic-based ion-selective thermoplastic electrode array for point-of-care detection of potassium and sodium ions

A microfluidic paper-based thermoplastic electrode (TPE) array has been developed for point-of-care detection of Na⁺ and K⁺ ions using a custom-made portable potentiometer. TPEs were fabricated using polystyrene as the binder and two different types of graphite to compare the electrode performance. The newly designed TPE array embedded in a polymethyl methacrylate chip consists of two working electrodes modified with carbon black nanomaterial and an ion-selective membrane, and an all-solid-state reference electrode modified with Ag/AgCl ink and poly(butyl methacrylate-co-methyl methacrylate) membrane via drop-casting. Ion-selective membrane compositions and conditioning steps were optimized. Under optimized conditions, ion-selective TPEs demonstrated fast response time (4 s) and good stability. The TPE array demonstrated a Nernstian behavior for K⁺ with a sensitivity of 59.2 ± 0.2 mV decade^-1 and near-Nernstian response for Na⁺ with a sensitivity of 54.0 ± 1.1 mV decade^-1 in the range 10^-1 - 10^-4 M and 1 -  10^-3 M, respectively. The detection limits were 1 × 10^-5 M and 1 × 10^-4 M for K⁺ and Na⁺, respectively. In addition, a K⁺ and Na⁺ selective microfluidic paper-based analytical device (µPAD) was applied to artificial serum analysis and found in good agreement with average recoveries of 101.3% and 99.7%, respectively, suggesting that the developed ISE array is suitable for detection of sodium and potassium in complex matrix.