Hyperkalaemia: Problem or Epi-phenomenon following Thrombectomy for Arteriovenous Fistulae and AV Grafts

Background: Arteriovenous fistulae/grafts (AVF/G) are felt to be superior to haemodialysis catheters (HDC). Their Achilles’ heel is thrombosis. This often requires intervention to 'rescue' the AVF/G, including percutaneous mechanical thrombectomy with thrombolysis [PMT] or venoplasty and stent insertion. Clot disruption by PMT carries a risk of hyperkalaemia. Some centres have protocols which do not allow PMT to be carried out if potassium (K) is > 5.0 mmol/l prior. Hyperkalaemia is less of a concern when performing thrombectomy by suction/Fogarty balloon. In our centre we perform PMT using Angiojet, a rheolytic thrombectomy device. Hence we decided to find out the magnitude of potassium rise following PMT. Methods: Data were prospectively collected from electronic records for patients who underwent PMT for thrombosed AVF/G between November 2021 – January 2024. Demographic characteristics, K pre and post-PMT, need for dialysis prior to procedure and complications associated with HDC insertion were recorded. Results: 15 procedures were performed in 32 patients. AVF:AVG = 19:13. M:F=20:12. Median age was 61 years (range 40-83). Mean time interval between thrombosis and thrombectomy was 3.02 days (range 1-7). Mean K at time of thrombosis was 5.34mmol/l (range 4 - 7.1). 28 patients had a HDC inserted pre-procedure, of which 21 patients had K > 5.0mmol/l. One non-functioning HDC needed re-insertion. Mean pre-PMT K was 4.54mmol/l (range 4.2 - 5.3). Mean post-PMT K was 4.72mmol/l (range 3.7-5.7); samples were obtained between 1 - 26 hours (mean 7.44) after the procedure. Mean change in K pre and post procedure (‘delta K’) was +0.19mmol/L (range -0.9 to +1.3). Conclusion: We report the outcomes of PMT in AVF/G with focus on change in K pre and post-procedure. The average potassium change was +0.19 mmol/L. None of the patients had severe or life-threatening hyperkalaemia following PMT. Some protocols mandate measures to reduce the K prior to PMT, in some cases this means performing dialysis through a new HDC. The rise in potassium following the procedure in our patients is quite small and suggests that the threshold for instituting potassium lowering measures prior to PMT could be raised without necessarily causing severe or life-threatening hyperkalaemia following the procedure.