Can rhabdomyolysis (Rhabdo) cause arrhythmias?

Rhabdomyolysis Causes Arrhythmias Through Hyperkalemia and Electrolyte Disturbances

Yes, rhabdomyolysis directly causes arrhythmias, primarily through hyperkalemia released from damaged muscle cells, which can progress to life-threatening ventricular arrhythmias and cardiac arrest if not promptly recognized and treated. 1, 2, 3

Primary Arrhythmogenic Mechanism: Hyperkalemia

The pathway from rhabdomyolysis to arrhythmias follows a predictable cascade:

• Muscle cell breakdown releases massive amounts of intracellular potassium into the circulation, creating hyperkalemia that directly destabilizes cardiac membranes and triggers dysrhythmias 1, 2, 3
• The American Heart Association recognizes that exertional rhabdomyolysis promotes hyperkalemia, lactic acidosis, and potentially lethal arrhythmias through this mechanism 1
• Hyperkalemia from rhabdomyolysis can cause fatal heart rhythm disturbances as one of the most serious complications of the syndrome 2

ECG Progression and Clinical Recognition

The ECG changes follow a predictable sequence that you must recognize immediately:

• Peaked T waves appear first at potassium levels >5.5 mmol/L, serving as the earliest warning sign 1
• The progression follows: peaked T waves → flattened P waves → prolonged PR interval → widened QRS → sine wave pattern → asystole 1
• Any ECG changes beyond peaked T waves (flattened P waves, prolonged PR, widened QRS) require immediate calcium administration for membrane stabilization 1

Additional Electrolyte-Mediated Arrhythmia Risk

Beyond hyperkalemia, rhabdomyolysis creates a perfect storm of arrhythmogenic factors:

• Hypocalcemia occurs early in rhabdomyolysis as calcium precipitates in damaged muscle tissue, further destabilizing cardiac conduction 3
• Hyperphosphatemia develops from muscle cell breakdown, contributing to metabolic derangements 3
• Metabolic acidosis from lactic acid production by damaged muscle undergoing anaerobic metabolism compounds the arrhythmia risk 1, 4, 2
• Hypomagnesemia may occur and must be corrected before treating hypokalemia or hypocalcemia, as these will be refractory to replacement otherwise 5

Critical Management Priorities

When rhabdomyolysis is suspected with any cardiac symptoms:

• Severe hyperkalemia (>6.0 mEq/L) with ECG changes mandates hospital admission with continuous cardiac monitoring 1
• Aggressive fluid resuscitation (15-20 mL/kg/h isotonic saline initially) is the cornerstone of treatment to restore hypovolemia and prevent further complications 4
• Monitor electrolytes (K, Mg, Ca) serially, as the release from damaged muscle continues over hours to days 5
• Check creatine kinase (CK), serum creatinine, complete metabolic panel with electrolytes, and urinalysis for myoglobinuria immediately 4

High-Risk Clinical Scenarios

Certain presentations carry particularly high arrhythmia risk:

• Exertional rhabdomyolysis in sickle cell trait patients creates a medical emergency with combined rhabdomyolysis, lactic acidosis, hyperkalemia, and impaired cardiac function 4
• Severe cases can progress to pulseless electrical activity from the combined metabolic insult of lactic acidosis, hyperkalemia, and hypocalcemia 4
• Disseminated intravascular coagulation from severe rhabdomyolysis worsens hypoxia and impairs cardiac function, creating additional arrhythmia substrate 1, 3

Common Pitfalls to Avoid

• Do not wait for myoglobinuria to appear before treating suspected rhabdomyolysis—it may be absent in up to 50% of cases, and arrhythmias can occur before visible myoglobin appears 6
• Never treat hypokalemia or hypocalcemia without checking and correcting magnesium first, as replacement will be ineffective 5
• Do not underestimate the arrhythmia risk in patients with "mild" rhabdomyolysis—even modest CK elevations can release enough potassium to cause life-threatening dysrhythmias in susceptible individuals 2, 3
• Self-resolution of peaked T waves indicates potassium normalization, but continued monitoring is essential as ongoing muscle breakdown can cause recurrent hyperkalemia 1

Prevention in At-Risk Populations

• The American College of Cardiology recommends that patients with history of exertional rhabdomyolysis implement gradual conditioning, adequate hydration, modified training pace, and immediate cessation of activity if warning symptoms develop 1
• Recognize that the arrhythmia risk persists for hours after the initial insult as muscle continues to break down and release intracellular contents 2, 3