The POTCAST study examined the effect of increasing potassium levels on the risk of ventricular arrhythmias in 1,200 patients with cardiovascular disease and an implantable cardiac pacemaker/defibrillator (ICD), with a mean age of 62.7 years, and 19.8% were women[1][2][3]. Patients were randomized to target high-normal potassium levels (4.5–5.0 mmol/L) using potassium supplements, mineralocorticoid receptor antagonists (MRAs), diet, or a combination thereof, versus standard care[2][3][4]. From a mean basal level of 4.01 mmol/l, an average of 4.36 mmol/l was reached in the intervention group after 6 months, while in the control group it was 4.05 mmol/l[1]. The primary endpoint (appropriate ICD therapy, sustained ventricular tachycardia, unplanned hospitalization for arrhythmia/heart failure, or death from any cause) occurred in 22.7% of patients (7.3 events per 100 person-years) in the intervention group versus 29.2% (9.6 events per 100 person-years) in the control group (HR 0.76; 95% CI 0.61–0.95; P=0.01)[2][3]. Median follow-up was 39.6 months[1][2][3]. The incidence of hospitalization for hyperkalemia or hypokalemia was 1% in both groups, and unplanned hospitalization or death occurred in 29.5% in the intervention group versus 33.2% in the control group (HR 0.88; 95% CI 0.72–1.08)[ 1 ]. Increasing potassium levels by approximately 0.3 mmol/L significantly reduced the burden of arrhythmias without safety risks[1][4].