For people at elevated risk of ventricular arrhythmias, sustaining high-normal potassium concentration levels lead to improved outcomes in a new randomized controlled investigation of 1,200 people with implanted cardioverter defibrillators (ICDs). The outcomes of the trial were published in the New England Journal of Medicine.

POTCAST Trial

The Danish study, named the POTCAST trial (Targeted Potassium Levels to Decrease Arrhythmia Burden in High-Risk Patients with Cardiovascular Diseases), after observing participants for 3.3 years. Researchers compared those whose potassium levels were elevated to the “high-normal” range (4.5–5.0 mmol/L) with a cohort whose levels were not particularly adjusted.

By the conclusion of the trial:

• 22.7% of high-normal potassium volunteers experienced significant cardiovascular incidents versus 29.2% in the untreated group.
  
• Just 15.3% of the high-normal cohort had ventricular tachycardia or needed ICD therapy, compared to 20.3% of the control group.
  
• Hospital admissions for arrhythmias were 6.7% in the high-normal cohort versus 10.7% in the untreated group.
  

Volunteers used a blend of dietary counseling, potassium supplements, and mineralocorticoid receptor antagonists (MRAs) to achieve the target levels within 85 days.

Why Potassium Matters for Heart Health

Potassium is important for maintaining the heart’s electrical stability. Too little potassium triggers arrhythmias, while excessive can also interrupt rhythms. As panelist Theresa McDonagh, MD, described , the investigation sought to discover a “good sweet spot” for potassium.

Cardiologist Morgan cautioned, “Low levels also can create a risk of arrhythmias, just as high levels can. This includes superventricular tachycardia, torsades de pointes, and even cardiac arrest in severe cases. Levels below 2.5 mmol/L carry a severe risk level, with levels between 2.5–2.9 mmol/L carrying a moderate risk level.”

She also added that excessively high potassium can be equally riskier: “The most serious risk is the very thing that is trying to be avoided by increasing the potassium range, which are arrhythmias, including ventricular fibrillation, and asystole [cessation of heart function].”

Beyond the heart, increased potassium may also affect muscles and nerves. “In addition to ECG changes, nerve and/or muscle function can be impacted, including diaphragmatic weakness,” Morgan cited.

Monitoring: Major Challenge

Increasing potassium isn’t easy. Trial volunteers underwent blood tests in each of two weeks to ensure their levels stayed in balance. Cardiologist Ziegelstein highlighted , “This is something we must consider when recommending potassium supplements to patients, or when treating patients with other medications that may increase serum potassium levels.”

He also warned that such constant monitoring is often unrealistic in day to day practice.

Expert Reactions

While Morgan labelled the results “interesting” and consistent with other researches , she showcased limitations:

• The mortality advantage wasn’t evident until year four.
  
• Volunteers in the active arm had, on average, more time since their ICD therapy, which might have impacted results.
  
• There were more hospital admissions for electrolyte issues like hyperkalemia, emphasizing the requirement for close supervision.
  

She also emphasized that comparing ancestral potassium-rich diets with today’s schedule is not simple: “The comparison of human ancestral diets that were richer in potassium and lower in sodium is confounding, as the life expectancy was frequently less than 45 years ancestrally.”

“In this study, participants had blood tests performed every other week to make sure that their potassium was in the desired range and neither too high nor too low — this is often very difficult to do in routine clinical practice,” Ziegelstein highlighted.

Disclaimer: This article is intended for educational or informational purposes only and does not substitute expert medical advice. Always consult a qualified physician before making alterations on your own. Do not self-medicate with supplements or change prescriptions without proper medical oversight.

FAQs:

Q1. What is potassium?
Potassium is an important mineral and electrolyte that helps to manage fluid balance, nerve signals, and heart rhythm. It is found in several food items such as bananas, potatoes, beans, and spinach.

Q2. Why is potassium significant for heart health?
Potassium aids the electrical activity of the heart and enables it to stabilize blood pressure. Both low and high levels can result in irregular heartbeats or cardiac issues .