TARGETING HIGH-NORMAL POTASSIUM LEVELS IN PATIENTS WITH IMPLANTABLE CARDIOVERTER–DEFIBRILLATORS (ICD)
Study finds higher potassium targets are beneficial in patients with ICDs and CVD
Straight Healthcare
October 2025
October 2025
Hypokalemia and low-normal potassium levels (<4.0 mEq/L) are known risk factors for ventricular arrhythmias in patients with cardiovascular disease. Consequently, maintaining high-normal potassium levels (4.5 - 5 mEq/L) in these patients may be beneficial. To examine the issue, researchers performed the POTCAST trial, where 1200 patients with an ICD (underlying heart disease: heart failure - 64%, ischemic heart disease - 50%, nonischemic cardiomyopathy and primary arrhythmia disorders - 50%) and a potassium of less than 4.3 mEq/L were randomized to a target potassium level of 4.5 to 5.0 mEq/L (high-normal group) or standard care. In the high-normal group, potassium levels were increased using potassium supplements, mineralocorticoid receptor antagonists (spironolactone or eplerenone), or both. Guidance on a potassium-rich diet was also provided, and potassium-losing diuretics were stopped if able. After a median follow-up of 39.6 months, the primary outcome (a composite of documented sustained ventricular tachycardia or appropriate ICD therapy, unplanned hospitalization for arrhythmia or heart failure, or death from any cause) was significantly lower in the high-normal group compared to standard treatment (22.7% vs 29.2%, P=0.01) Appropriate ICD therapy or documented ventricular tachycardia and unplanned hospitalization for arrhythmia accounted for the majority of the difference in the primary end point. Hospitalization for hyperkalemia or hypokalemia was similar between groups.
The protocol for achieving the target range included initial visits every other week for blood tests and medication adjustments. The median duration for this intensive adjustment period was 85 days. Despite this rigorous protocol, only 42% of participants in the high-normal potassium group achieved a target potassium level. This type of frequent monitoring would be impractical in most routine outpatient practices. However, this study does offer an important takeaway: the beneficial effect was not dependent on achieving the high-normal target, suggesting the goal should be to avoid hypokalemia or low-normal potassium levels in this patient population.
The protocol for achieving the target range included initial visits every other week for blood tests and medication adjustments. The median duration for this intensive adjustment period was 85 days. Despite this rigorous protocol, only 42% of participants in the high-normal potassium group achieved a target potassium level. This type of frequent monitoring would be impractical in most routine outpatient practices. However, this study does offer an important takeaway: the beneficial effect was not dependent on achieving the high-normal target, suggesting the goal should be to avoid hypokalemia or low-normal potassium levels in this patient population.
