Exceptional prevalence of interatrial block in a general hospital population

Background: Interatrial block (IAB: P wave greater than or equal to 110 ms) is a strong correlate of left atrial (LA) enlargement and an important pre dictor of supraventricular tachyarrhythmias, notably atrial fibrillation an d flutter. It is surprising that, despite its association with arrhythmias and its effects on the electromechanical properties of the left atrium, the re is widespread neglect of this common abnormality. Hypothesis: The study was undertaken to investigate the prevalence of JAB i n a general hospital population. Methods. We prospectively evaluated the electrocardiograms of 1,000 consecu tive adult patients, analyzed for P-wave duration. Results: Our results showed a very high prevalence of IAB (41. 1% of patien ts in sinus rhythm and 32.8% of all patients). As expected, it was more com mon inpatients aged > 60 years. Conclusions: Given this unusually high prevalence, of IAB in hospital patie nts and its ominous portents (LA enlargement, thrombosis and embolism, arrh ythmias), physicians should be aware of its frequency and computer software should be programmed to recognize it.