A slightly enlarged left atrium is not exactly the same as an enlarged left atrium. An enlarged left atrium is defined as a left atrium with an internal diameter of 35mm or more, which may be mildly enlarged or severely enlarged. During an ECG, a bimodal shape of the P-wave will be found, which is common in mitral stenosis, hypertension or restrictive cardiomyopathy. A slightly enlarged left atrium is a mild enlargement of the left atrium, which is not serious if it is not combined with an enlarged left ventricle or other structural changes in the heart. Thus, a slightly enlarged left atrium falls under the category of left atrial enlargement. Once the ECG shows that the left atrium is slightly enlarged, it is recommended to cooperate with your doctor for further examination to clarify whether there is left ventricular enlargement or other atrial chamber enlargement, so as to promptly exclude the possibility of cardiac system-related diseases. Even if the left atrium is only mildly enlarged, it is recommended to review the examination regularly and pay attention to the changes of the left atrium.