Raising Potassium Lowers Arrhythmia Risk in ICD Patients
A large randomized trial shows that boosting potassium levels in patients with implantable cardioverter-defibrillators reduces arrhythmia events and ICD shocks.
The POTCAST trial, presented at ESC 2025 found that actively increasing plasma potassium levels in high-risk patients with cardiovascular disease and ICDs reduced arrhythmia-related events by 24%.
Study Details
The trial included 1,200 patients with cardiovascular disease and an implantable cardioverter-defibrillator (ICD). All participants had baseline potassium levels below 4.3 mmol/L and preserved to moderately impaired kidney function.
Patients were randomized to either standard care or an intervention designed to increase plasma potassium to the high-normal range of 4.5–5.0 mmol/L.
Methodology
The intervention combined dietary counseling to encourage potassium-rich foods with pharmacologic support such as mineralocorticoid receptor antagonists and potassium supplements.
Potassium-sparing diuretics were reduced when possible. Patients were followed every six months with blood tests, ECGs, and ICD data collection. The trial was conducted in Denmark and funded by national research foundations.
Key Findings
Patients who increased their potassium by about 0.3 mmol/L had 24% fewer serious heart rhythm problems, ICD shocks, hospitalizations, or deaths. Most of the benefit came from a 25% drop in episodes of ventricular tachycardia.
The treatment was generally safe, with no major increase in kidney or electrolyte problems.
Implications for Practice
For patients with ICDs and low-to-normal potassium levels, modestly increasing plasma potassium into the high-normal range may meaningfully reduce arrhythmia burden and ICD shocks, improving quality of life.
The trial suggests that potassium supplementation and dietary adjustments represent a simple, low-cost, and widely available strategy.
Clinicians must remain cautious in patients with advanced kidney disease or multiple comorbidities, where hyperkalemia risk is greater. While findings are strongest for ICD patients, the broader cardiovascular population may also benefit, particularly given the generally low potassium intake in modern diets.