PR interval prolongation is a diagnostic term used on ECG reports to refer to a prolongation of the time it takes for electrical signals from the atria to reach the ventricles, and its severity is determined by the cause of the prolonged PR interval. The normal PR interval should be 0.12 to 0.20 seconds. If the PR interval exceeds 0.20 seconds, it often indicates atrioventricular block, i.e., the transmission of signals from the atria to the ventricles is impeded, which may be caused by physiologic and pathologic factors. 1. Physiological factors: Mild PR interval prolongation is usually asymptomatic, requires no treatment, and is less severe. It is usually due to recent poor nutritional status and poor sleep quality. After removing the triggers, the PR interval will return to normal. A few drugs may also cause PR interval prolongation, such as saquinavir and escitalopram. 2. Pathological factors: changes in cardiac structure (dilated cardiomyopathy, hypertrophic cardiomyopathy, etc.), pericarditis, arrhythmia, hyperkalemia, heart failure, coronary artery disease and other causes can lead to prolongation of the PR interval, which is more serious, and need to be vigilant. It suggests organic lesions of the heart, and further examinations such as cardiac ultrasound, nuclear myocardial imaging, coronary CTA, etc. are needed to clarify the cause of the disease. When PR interval prolongation occurs, need to actively consult the doctor, follow the doctor’s instructions for reasonable treatment.