Background: The present study of patients with Wenckebach-type second-degree sinoatrial block (W-block) evaluated the probability of the development of a more advanced grade of sinoatrial block. Data on the clinical significance of W-block are limited. It is unknown whether W-block predicts a more advanced grade of sinoatrial block.
Methods: Standard ECGs of 412 patients with symptoms that might have been related to cardiac arrhythmias were reviewed for the presence of W-block. In the initial ECG W-block occurred in 29. During the follow-up period of 62 ± 35 months the main end-point was the first episode of type II second-degree sinoatrial block. An additional end-point was the occurrence of a sinus pause greater than 3 s or the development of type II second-degree sinoatrial block.
Results: Of the 29 patients with W-block initially, 6 (20.7%) developed higher grade sinoatrial block, and sinoatrial arrhythmic events occurred in 9 (31%). In the 383 patients without W-block subsequent episodes of higher grade sinoatrial block occurred in 14 (3.7%) and sinoatrial arrhythmic events in 28 (7.3%). A multivariate Cox analysis identified W-block as an independent marker for developing type II second-degree sinoatrial block (HR = 3.72, 95% CI 1.39-9.99) and for the occurrence of sinoatrial arrhythmic events (HR 3.01, 95% CI 1.37-6.58).
Conclusions: In patients with symptoms that might be caused by cardiac arrhythmias the presence of W-block in a standard ECG indicates a high probability of developing a more advanced grade of sinoatrial block. (Cardiol J 2007; 14: 391-395)