The ECG may simply show sinus rhythm or sinus bradycardia. This is different than a first-degree atrioventricular, or AV, block, which shows a prolonged PR interval. Second-degree sinoatrial exit ...

such as sinus bradycardia, sinus arrhythmia, first-degree atrioventricular (AV) block, early repolarisation, incomplete right bundle branch block (IRBBB) and voltage criteria for left ventricular ...

including sinus pause, heart block, and cardiac arrest have occurred with the use of Toprol-XL. Increased risk for bradycardia in patients with first-degree AV block, sinus node dysfunction ...