Objective To investigate the electrocardiographic manifestations of excessive prolonged PR interval syndrome. Methods Five patients with excessively prolonged PR interval were selected and analyzed

and their electrocardiograms were analyzed. Results Excessive prolongation of the PR interval showed complex ECG performance. The P wave is mistaken for the U wave; the ventricle induced by supraventricular agitation is mistaken for the ventricular or junctional escape beat; the relationship between the P wave and the QRS complex is misdiagnosed; the degree of AV block is misdiagnosed. Conclusions The ECG appearance of excessive PR interval is helpful for clinical diagnosis of PR interval excessively prolonged syndrome.