The effect of increased plasma potassium on myocardial function; a randomized POTCAST substudy.

Area of Science:

• Cardiology
• Electrophysiology
• Internal Medicine

Background:

• High-normal plasma potassium (p-K) levels may reduce cardiovascular arrhythmias and mortality.
• The impact of elevated p-K on myocardial function in patients with reduced ejection fraction is not fully understood.
• Left ventricular ejection fraction (LVEF) is a critical indicator of heart function.

Purpose of the Study:

• To investigate if increasing p-K to high-normal levels improves systolic and diastolic myocardial function.
• To assess changes in Global Longitudinal Strain (GLS) and diastolic parameters in patients with LVEF 35-55%.

Main Methods:

• A randomized controlled trial (POTCAST) involving 50 patients with LVEF 35-55%.
• Intervention group received guidance on potassium-rich diets, supplements, and mineralocorticoid receptor antagonists to achieve p-K of 4.5-5.0 mmol/l.
• Echocardiography assessed GLS, mechanical dispersion, E/A, e', and E/e' at baseline and after 44 days.

Main Results:

• The intervention group achieved a mean p-K increase of 0.52 mmol/l compared to controls (P<0.001).
• Significant improvements were observed in GLS (mean difference -1.0%, P<0.05) and e' (mean difference 0.9 cm/s, P=0.04).
• Diastolic function improved, indicated by a significant change in E/e' (P=0.03).

Conclusions:

• Inducing high-normal plasma potassium levels positively impacts systolic and diastolic myocardial function.
• This approach may be beneficial for patients with low-normal to moderately reduced left ventricular ejection fraction.
• Targeting potassium levels represents a potential strategy for improving cardiac function in at-risk populations.