Transient Left Bundle Branch Block in the Setting of Hyperkalemia

Area of Science:

• Cardiology
• Nephrology
• Electrophysiology

Background:

• Hyperkalemia is a critical electrolyte imbalance with significant cardiovascular risks, including arrhythmias and sudden cardiac death.
• End-stage renal disease (ESRD) patients are particularly vulnerable to hyperkalemia due to impaired renal potassium excretion.
• Left bundle branch block (LBBB) is a recognized electrocardiogram (EKG) finding, often associated with underlying structural heart disease.

Observation:

• A 48-year-old female with ESRD presented with weakness and dyspnea following a missed hemodialysis session.
• Electrocardiogram (EKG) revealed a transient left bundle branch block (LBBB) pattern, left axis deviation, prolonged PR interval, and peaked T-waves.
• Initial serum potassium level was critically elevated at 8.5 mEq/L.

Findings:

• The observed LBBB pattern on EKG was directly attributable to severe hyperkalemia.
• Prompt correction of the serum potassium level led to the complete resolution of the EKG abnormalities, including the LBBB.

Implications:

• This case highlights the importance of considering and rapidly assessing for hyperkalemia in patients with ESRD presenting with new-onset EKG changes suggestive of LBBB.
• Recognizing hyperkalemia as a reversible cause of LBBB can prevent misdiagnosis and guide appropriate, timely management, potentially averting adverse cardiac events.
• Clinicians should maintain a high index of suspicion for hyperkalemia-induced EKG changes in at-risk populations, emphasizing the critical role of electrolyte monitoring.