A MULTICENTRE Danish trial has shown that actively increasing plasma potassium levels to the high-normal range significantly lowers the risk of ventricular arrhythmias, unplanned hospitalisation, and death among patients with implantable cardioverter-defibrillators (ICDs).
Hypokalaemia and even low-normal potassium levels are known to increase arrhythmic risk in patients with cardiovascular disease, yet strategies to optimise potassium have been understudied. The POTCAST trial enrolled 1,200 high-risk participants with baseline plasma potassium ≤4.3 mmol/L across multiple centres in Denmark. Participants were randomised 1:1 to either a treatment strategy aimed at raising potassium to 4.5–5.0 mmol/L (using potassium supplementation, mineralocorticoid receptor antagonists, or both, along with dietary guidance and standard care) or to standard care alone. The primary composite endpoint included documented sustained ventricular tachycardia or appropriate ICD therapy, unplanned hospitalisation for arrhythmia or heart failure, or death from any cause, assessed in a time-to-first-event analysis.
Over a median follow-up of 39.6 months, the primary endpoint occurred in 136 participants (22.7%; 7.3 events per 100 person-years) in the high-normal potassium group versus 175 participants (29.2%; 9.6 events per 100 person-years) in the standard-care group. This corresponds to a hazard ratio of 0.76 (95% CI: 0.61–0.95; P=0.01). Notably, rates of hospitalisation for either hyperkalaemia or hypokalaemia were similar between the groups, indicating the intervention was safe and well tolerated.
The findings suggest that actively targeting high-normal potassium levels can provide meaningful protection against life-threatening ventricular arrhythmias and related hospitalisations in ICD patients. POTCAST supports potassium optimisation as a practical adjunctive strategy in high-risk patients with cardiovascular disease, highlighting the role of electrolyte management in modern arrhythmia prevention.
Reference
Jons C. POTCAST – a randomized controlled trial of arrhythmia prevention using targeted plasma potassium levels in ICD patients. ESC Congress 2025, 29 August-1 September, 2025.
