Nakayma M, et al. - In patients with coronary heart disease and patients with noncardiac diseases, researchers analyzed ECG records to determine and compare the prevalence and response of J waves to sudden shortening of the RR interval on the conducted atrial premature beat (APB) as well as to determine change in the QRS complexes on the APB. An APB was present in 243 patients who had percutaneous coronary intervention (PCI) for acute myocardial infarction (MI) or angina pectoris (AP), among overall 17,013 patients. Sixteen patients (6.6%) had J waves. J waves (2.6%) were also seen in 19 patients among an additional 729 patients with noncardiac diseases and APB. Almost similar clinical features were seen between the ischemic and non-ischemic groups. In the ischemic group, J waves were located more often in inferior and high lateral leads. Findings revealed augmentation of J waves at short RR intervals together with distinct changes in the QRS complexes in patients with chronic coronary heart disease and in patients with non-cardiac diseases. Also, an augmentation of J waves at short RR interval could represent a conduction delay.