A low voltage electrocardiogram result can be caused by a problem in the heart's ability to generate electricity or can be due to the presence of fluid or air in the chest between the electrodes and the heart. Chronic heart diseases, such as cardiomyopathy, can cause low voltage ECGs.
Low voltage ECGs can also be caused by fluid around the heart blocking the electrical signal. Chronic obstructive pulmonary disease can also cause low voltage ECGs due to hyper-inflation of the lungs or pneumothorax. Low voltage ECGs are common after open-beat heart surgery.
If low voltage ECG is a new finding, it may indicate the presence of cardiac tamponade, which is a medical emergency.