In this episode, I’ll discuss aiming for high-normal potassium to reduce sustained ventricular tachycardia in patients with an ICD.
Both hypokalemia and hyperkalemia are associated with ventricular arrhythmias and sudden death. This is sometimes referred to as a U-shaped association due to the graphical representation of mortality risk vs potassium levels forming a U, where the risk of mortality is lowest at normal potassium levels and increases significantly at both extremely low and high levels.
However the bottom of the U where mortality is lowest does not perfectly correlate to the normal laboratory range for potassium of 3.5-5 mEq/L. Researchers from Denmark published in New England Journal of Medicine a multicenter, open-label, event-driven, randomized superiority trial to determine if aiming for the high end of normal potassium (4.5-5 mEq/L) had beneficial effects on patient outcomes.
The authors randomized 1200 patients with an ICD and a baseline potassium level of 4.3 or lower 1:1 to either usual care or the high-normal potassium group. Patients in the high-normal group were given potassium supplementation, a mineralocorticoid receptor antagonist, or both plus dietary guidance in an effort to get their potassium between 4.5 and 5 mEq/L. The study used a composite endpoint of documented sustained ventricular tachycardia or appropriate ICD therapy, unplanned hospitalization (>24 hours) for arrhythmia or heart failure, or death from any cause.
A primary end-point event occurred in 22.7% of the patients in the high-normal potassium group compared with 29.2% in the usual care group. This difference was statistically significant with a hazard ratio of 0.76 in favor of the high-normal potassium group. There was no difference between groups in the incidence of hospitalization for hyperkalemia or hypokalemia.
The authors concluded:
Among participants with any cardiovascular disease who had an ICD and were at high risk for ventricular arrhythmias, a treatment-induced increase in plasma potassium levels led to a significantly lower risk of appropriate ICD therapy, unplanned hospitalization for arrhythmia or heart failure, or death from any cause than standard care.
Pharmacists should be aware that in at-risk patients such as those with an ICD, the lab range for potassium levels does not match the goal range to minimize cardiovascular events in this patient population.
The article in this episode is a selection from my Hospital Pharmacy Academy’s weekly literature digest. Have you ever felt like your physician colleagues are one step ahead of you with new literature developments? Every week, Academy members are provided a summary curated and explained by me of the top hospital pharmacy-related articles published that week from over 20 major journals and sources to save you time and keep you up to date with the literature. To get immediate access, go to pharmacyjoe.com/academy.
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