Acute myocardial infarction (AMI) in patients over 65 years of age represent more than half of the patients with AMI. Among them, between 60 and 80% represent the first AMI. The objective of this study is to evaluate the behavior of AMI in this group of patients. The clinical charts of patients over 65 years of age with ischemic heart disease admitted into the hospital during the past two years, were reviewed. We used the international criteria (clinical, ECG, enzymatic, echocardiographic and scintigraphic studies) for the diagnosis of AMI. Patients with previous AMI were excluded. We included 274 patients (68% males and 32% females). The age varied from 65 to 91 years with an average of 71.7 +/- 5.3 years. Typical symptoms were present in 90.5% and atypical in 9.5% of the cases, being the latest most frequent in those over 75 years of age. METHODS cigarette smoking was present in 60% of the patients, hypertension in 52% and diabetes mellitus in 37%. Both of them were associated in 21%. In 144 cases (52.5%) the MI localization was anterior and in 130 (47.5%) inferior; among them 47 patients (36%) had extension to the right ventricle and 7 (2.5%) had a non Q AMI. RESULTS Type I-II VPCs of Bernard Lown were present in 18% and type V 10.2%. Compete AV block in 14.2% (all of them with inferior wall MI); bifascicular block in 55 and mitral insufficiency due to papillary muscle dysfunction in 6.5%.(ABSTRACT TRUNCATED AT 250 WORDS)