Marked first-degree AV block may lead to complete AV block development

Abstract Funding Acknowledgements Type of funding sources: None. Background First-degree atrioventricular (AV) block (PR interval >200 ms) is considered a benign condition with rare progression to higher degree AV block. The site determined electrophysiological (EP) study and measurement His-ventricular (HV) interval, normal values below 55 ms. Prolonged HV > 70 ms predictive higher-grade development. Marked first-degree PR 300 may lead symptoms such as fatigue, poor exercise tolerance palpitations. When are correlated the conduction delay, permanent pacemaker (PPM) implantation restore synchrony should be considered. In Framingham heart study, patients had threefold risk PPM implantation. However, there no data on intervals rate disorder in marked Purpose To assess value for higher-degree disorder. Methods We prospectively evaluated consecutive symptomatic that underwent His electrograms were recorded during implantation, measured from first deflection signal earliest onset ventricular activation 12-lead surface ECG. Patients followed 6 months three out-patient visits, which was temporarily inhibited check intrinsic conduction. Results Seventeen between January 2020 September 2022. Ten (59%) male, 7 (41%) female, an average age 61 ± 19 years. All markedly prolonged (383 47 narrow QRS complex (100 16 ms). Three (17%) intermittent type 1 second-degree block, right bundle branch two (12%) left anterior fascicular four (24%) patients. Except one patient corrected atrial septal defect, echocardiographic signs structural disease ejection fraction 5%. upper limit at 54 6ms above Two developed complete follow-up: 28 83 years old, respectively, 392 363 ms, 104 94 57 48 None any additional blocks time implant. Conclusion our cohort (PR>300 ms), despite Closer monitoring, beyond only EP measurements, warranted potential