Written by Vivian Lei
Spoon Feed
In patients with an implantable cardioverter-defibrillator (ICD) at risk for ventricular arrhythmias, keeping potassium in the high-normal range (4.5-5.0 mmol/L) reduced shocks, arrhythmia hospitalizations, and deaths, without added harm.
The real K-Pop hit: raising potassium, reducing ICD shocks
The POTCAST trial, a large Danish randomized study, asked whether deliberately raising potassium into the high-normal range (4.5-5.0 mmol/L) could protect patients with implantable cardioverter-defibrillators (ICDs) from ventricular arrhythmias and related complications. All 1200 participants had baseline potassium ≤4.3 mmol/L and were considered at high arrhythmia risk. They were randomized either to usual care or to an intervention that included potassium supplementation, mineralocorticoid receptor antagonists (spironolactone/eplerenone), and potassium-rich dietary guidance.
Patients were followed for a median of 40 months. The primary composite outcome included sustained VT, appropriate ICD therapy, arrhythmia or heart failure hospitalization, or death. This occurred in 22.7% of the high-normal potassium group versus 29.2% in the standard-care group. The number needed to treat to prevent one event was 13. The treatment strategy did not cause more hyperkalemia hospitalizations compared with control.
How will this change my practice?
Based on this study, aiming toward the high-normal potassium range may reduce arrhythmia burden and unnecessary ICD shocks. I intend to pay closer attention to potassium management in cardiac patients at risk for ventricular arrhythmias, and I anticipate this study will help me better understand therapeutic strategies recommended by my patients’ cardiologists.
Editor’s Note: I would have been interested by a sub-group of only the patients who received potassium supplementation. The other interventions are well known heart failure treatments and may have affected the outcomes through mechanisms besides potassium elevation. Especially since target potassium levels were not attained. ~ Nick Zelt
Source
POTCAST Study Group. Increasing the Potassium Level in Patients at High Risk for Ventricular Arrhythmias. N Engl J Med. 2025 Aug 29. doi: 10.1056/NEJMoa2509542. Epub ahead of print. PMID: 40879429.
