160 survivors of acute myocardial infarction (AMI) were evaluated to assess the clinical significance of supraventricular tachyarrhythmias (SVTA) occurring at discharge from the hospital after the acute event. All the variables considered for the study were estimated before hospital discharge; arrhythmias were quantified with a 24 h Holter ECG monitoring system. SVTA occurred in 88 patients (55%). Single or repetitive supraventricular premature beats were found in 65 (41%), paroxysmal atrial or junctional tachycardias in 20 (12%), bouts of atrial flutter or fibrillation in 3 (2%). Bivariate statistical analysis showed no relationship between sex, previous cardiovascular history, type, and location of AMI and SVTA occurrence. A close positive relationship was found between age, left atrial dimension (LAD), cardio-thoracic ratio (CTR) and SVTA occurrence; an inverse relationship was found for left ventricular ejection fraction (LVEF). The presence of SVTA appeared significantly related to age above 55 years, to LAD greater than 40 mm, to LVEF less than 45%, to serum creatine kinase peak levels over 1400 U l-1 and to CTR over 0.49. Multivariate statistical analysis showed that five variables are important in discriminating patients suffering from SVTA: age, LAD, LVEF, left ventricular fractional shortening, and CTR. SVTA occurring at discharge from hospital after AMI are indicative of impaired left ventricular pump function.

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To assess the usefulness of a step by step evaluation of exercise left ventricular ejection fraction (LVEF), 219 consecutive patients with recent uncomplicated myocardial infarction and 30 normal subjects underwent a symptom-limited cycloergometer test followed by exercise radionuclide ventriculography (ExRNV). LVEF was monitored throughout the whole test. 49 patients underwent coronary arteriography for clinical reasons. 5 patterns of exercise LVEF could be observed: progressive increase: 55 patients (25%) and 27 normal subjects (90%); progressive decrease: 37 patients (17%); initial increase followed by significant decrease: 54 patients (25%); lack of initial modification and terminal decrease: 35 patients (16%); no modification: 38 patients (17%) and 3 normal subjects (10%). Grouping the patients in this fashion allowed us to increase the specificity of ExRNV from 70% to 100%, without loss of sensitivity (95%). As for the patients in subgroup C, 32/54 showed unequivocal ECG ischaemic changes, occurring simultaneously with LVEF decrease; in 33/54 LVEF dropped during the last workload; in 25/54 the last stage LVEF was equal to or higher than the basal LVEF. The statistical analysis showed that ischaemic ECG changes (P less than 0.0001), exercise-induced wall-motion abnormalities (P less than 0.0001), and the presence of multivessel coronary artery disease (P less than 0.0001) were significantly more frequent in patients showing patterns (b)-(d), which should be considered as ischaemic. Our method allowed the unequivocal identification of ischaemic patterns in LVEF during exercise, which might be missed if only its basal and final values are considered.