Abstract
Following the development of CCU, rate of death due to fatal arrhythmia in acute myocardial infarction (aMI) has been markedly reduced, on the other hand, circulatory failure presents remaining problem as notorious cause of death in this clinical catastrophe. Attempt has been made to evaluate the left ventricular performance in the acute stage of myocardial infarction, in which systolic time intervals (STI) were used by non-invasive technique. The relationship of STI with prognosis was also studied, and the results were compared with those of old myocardial infarction. Materials and Methods: In 30 cases of aMI with an average age of 60.2 years, admitted to the CCU, phonocardiogram, electrocardiogram, and carotid pulse tracings were simultaneously recorded, after exclusion of cases with atrial fibrillation, left bundle branch block, and frequent supraventricular or ventricular premature beats. Diagnosis was based on clinical signs, electrocardiogram, and serum enzyme studies. Transmural infarction was noted in all cases. The tracings were recorded by a Fukuda MCM-800 polygraph and TY-303 transducer with paper speed of 100mm/sec, as early as possible on the admission day. Thereafter the recordings were performed in every morning in the CCU, then once a weak after transfer to the general ward until discharge. Recording was carried out to ensure measurement of R-R, I-II, total electromechanical systole (Q-II), and left ventricular ejection time (LVET) in 5 consecutive cycles. Using the average values, pre-ejection period (PEP) was calculated as (Q-II)-LVET, and isometric contraction time (ICT) as (I-II)-LVET, and PEP/LVET to be expressed as a percentage of the ratecorrected normal value according to Sawayama et al. Clinical signs were classified into the following two categories: Group 1: Complete absence of left ventricular heart failure (16 cases). Group 2: Definite left ventricular heart failure with dyspnea, auscultatory and chest x-ray abnormalities, including those requiring digitails administration though left ventricular failure was not always evident (10 cases). Death occurred during hospitalization in 4 cases, all with heart failure. These were classified in a separate group.
