[Bradyarrhythmias in the acute phase of myocardial infarct]

The functioning of the Intensive Care Units has permitted a better study and treatment of the arrhythmias which complicate the acute phase of myocardial infarction. 1,100 charts of patients admitted to the Coronary Unit of the National Institute of Cardiology of Mexico were reviewed. Acute myocardial infarction was demonstrated in 819 of them by the usual methods. The frequency and characteristics of the following bradiarrhythmias were studied: sinus bradicardia, sinus stoppage, seno-atrial block, migration of the atrial pacing, union rhythm and slow ventricular tachycardia. Sinus bradicardia was presented in 23.7% of the infarctions, sinus stoppage in 2.4%, migration of the atrial pacing in 9.4%, nodal rhythm in 7.2% and slow ventricular tachycardia in 7.8%. Bradiarrhythmias, generally considered as "lesser" arrhythmias, favor the appearance of lethal arrhythmias, regardless of the degree of mechanical failure, and thus should be treated actively.