Electrolyte-Related ECG Abnormalities in Acute GI Illness

Mechanism and Clinical Evidence

• The American Heart Association acknowledges that acute gastrointestinal issues can cause ECG T-wave abnormalities, primarily through electrolyte disturbances—particularly hypokalemia from vomiting and diarrhea—which produces characteristic T-wave flattening, ST-segment depression, and prominent U waves that can even mimic myocardial ischemia 1
• Hypokalemia is the most common electrolyte abnormality resulting from vomiting and diarrhea, causing potassium loss that directly affects cardiac repolarization 1
• ECG changes from hypokalemia include: T-wave flattening or inversion, ST-segment depression, and prominent U waves 1
• Hypokalemia produces: broadening of T waves, ST-segment depression, and prominent U waves that may be more prominent than the T wave itself 1

Diagnostic Approach and Management

• The American College of Cardiology recommends immediately checking serum potassium, magnesium, and calcium levels before attributing T-wave changes to cardiac ischemia 1
• Obtaining detailed history of vomiting, diarrhea, and diuretic use is crucial, as these are the primary mechanisms for electrolyte depletion 1
• If ECG abnormalities persist despite electrolyte correction, consider alternative cardiac causes including ischemia, myocarditis, or cardiomyopathy 2, 3