What causes peaked T waves on an electrocardiogram (ECG)?

From the Guidelines

Peaked T waves on an ECG are primarily caused by hyperkalemia, which is an elevated level of potassium in the blood, as evidenced by the most recent study in 2021 1. This electrolyte abnormality affects cardiac cell membrane polarization, leading to characteristic tall, narrow, and symmetric T waves on the electrocardiogram.

• Key points about hyperkalemia include:
  • Potassium levels above 5.5 mEq/L can produce these changes, with more pronounced T wave peaking as levels increase.
  • Other causes of peaked T waves include early myocardial infarction, left ventricular hypertrophy, cerebral injury, and certain medications like digitalis.
  • Hyperkalemia requires prompt treatment based on severity, including calcium gluconate to stabilize cardiac membranes, insulin with glucose to shift potassium intracellularly, and sodium bicarbonate in cases of acidosis.
  • Severe hyperkalemia (>6.5 mEq/L) may require emergent dialysis, as noted in the 2021 study 1. The peaked T waves occur because excess extracellular potassium alters the normal potassium gradient across cell membranes, accelerating repolarization and creating the characteristic ECG pattern that serves as an early warning sign of potentially life-threatening electrolyte disturbance, as described in the 2010 American Heart Association guidelines 1.
• Treatment options for acute hyperkalemia, as outlined in the 2021 study 1, include:
  • Intravenous calcium gluconate administration to rapidly reduce the membrane excitatory effects of K+ on cardiac tissue.
  • Intravenous insulin (plus glucose) and inhaled β-agonists to promote redistribution of serum K+ into the intracellular space.
  • Short-term treatment with oral sodium bicarbonate to promote K+ excretion in patients with concurrent metabolic acidosis.
  • Dialysis to increase K+ elimination from the body, which may be used as an adjunctive therapy in acute hyperkalemia.

From the Research

Causes of Peaked T Waves on ECG

• Peaked T waves on an electrocardiogram (ECG) are often associated with hyperkalemia, a condition where the serum potassium level is elevated above 5.5 mmol/l 2, 3, 4.
• Hyperkalemia can be caused by various medical conditions, such as chronic kidney disease (CKD), diabetes mellitus, and other disorders that affect potassium levels in the body 4.
• In addition to hyperkalemia, peaked T waves can also be seen in patients with multiple electrolyte imbalances, including hypocalcemia and hypomagnesemia 3.
• The presence of peaked T waves is not always a reliable indicator of hyperkalemia, as other factors such as the patient's overall health and the presence of other electrolyte imbalances can influence the ECG reading 2, 5.

Electrocardiographic Manifestations

• The ECG can be a useful tool in identifying patients with hyperkalemia, but the accuracy of the diagnosis depends on various factors, including the severity of the condition and the presence of other electrolyte imbalances 2, 3.
• In patients with acute kidney injury (AKI), electrocardiographic changes in T waves are poor predictors of serum potassium levels and the presence of hyperkalemia 5.
• Other ECG abnormalities, such as a prominent U wave and prolongation of the descending limb of the T wave, can also be seen in patients with hyperkalemia and multiple electrolyte imbalances 3.

Clinical Considerations

• Hyperkalemia is a life-threatening condition that requires prompt treatment, and the ECG can be a useful tool in diagnosing the condition 2, 4.
• The management of hyperkalemia involves various therapies, including insulin and glucose, which can help to reduce serum potassium levels 4, 6.
• However, the use of insulin and glucose can also increase the risk of hypoglycemia, and patients should be monitored closely for this complication 6.