Arrhythmias Complicating Acute Myocardial Infarction—Bradyarrhythmias

In acute myocardial infarction (AMI) in addition to myocardium, the specialized conduction system can be affected directly by ischemia, necrosis, or auto-nomic imbalance [1]. Many serious arrhythmias develop within 1 hour of onset of symptoms, before presentation to the hospital and patient monitoring [2, 3]. It is important to recognize and treat them in this setting, as they may complicate the course and have prognostic signifi cance [4–10].

Bradycardia is defi ned as a heart rate less than 60 beats per minute and is usually caused either by a failure of the sinus node (SN) impulse generation or failure of impulse propagation in distal conduction system [11]. The diagnosis of bradyarrhythmia starts with physical examination and is confi rmed by electrocardiogram. The two most frequent bradycardic rhythms in the setting of AMI are sinus bradycardia, seen in 30%to 40 %of patients [12–14], and atrio-ventricular (AV) block, seen in 4%to 20%of patients with the following occurrence: 8%to 15 % fi rst-degree, 5% to 12% second-degree, and 6% to 8% third-degree AV block [15–17]. Most of these arrhythmias are associated with inferior AMI [4–10, 16, 18]. The incidence of bradyarrhythmias has decreased in the era of thrombolysis and early invasive revascularization [4, 5, 8].