ECG findings

  QT interval is shortened due to shortening of the ST segment. When compared with the second half (descending limb) of the T wave, the first half (ascending limb) of the T wave is more steep. In normal subjects, the descending limb of the T wave is normally more steep than the ascending limb.

  When serum calcium level is above 16 mg/dL, T wave time starts to prolong and shortened QT interval starts to disappear.

  ST segment elevation (mimicking acute myocardial infarction) may be observed.

  Left bundle branch block (rare).

Clinical significance

  Hypercalcemia may ease the emergence of digoxin intoxication in patients taking digoxin.

  Significant elevation of serum calcium level may give the appearence of acute myocardial infarction.

  The sensitivity and specificity of ECG findings of hypercalcemia are not high. Absence of the anticipated ECG findings does not necessarily rule out the possibility of hypercalcemia.


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ECG 1. The ECG above belongs to a 69 years old woman. ST segment elevation in anterior leads give the impression of acute
anterior myocardial infarction. However, this patient has normal cardiac enzymes and chest pain is absent: she is not
experiencing acute myocardial infarction. Her corrected serum calcium level was found to be 20.36 mg/dL (5.09 mmol/L).
In patients with no signs and symptoms of acute coronary syndrome, hypercalcemia should be included among the differential
diagnosis of ST segment elevation.

Dr. Laura C. Wesson has donated the above ECG to our website.

Click here for a more detailed ECG