Risk Factors Indicating Recurrent Myocardial Infarction After Recovery From Acute Myocardial Infarction

Daiji Saito, Teruo Shiraki, Takefumi Oka, Akio Kajiyama, Toshiyuki Takamura
2002 Circulation Journal  
yocardial infarction (MI) is now one of the most frequent causes of death in elderly subjects in Japan; in 1999 approximately 15,000 cardiac deaths occurred in Japan and the majority was related to myocardial infarction (MI). 1 Furthermore, among survivors of an acute MI (AMI), the incidence of a subsequent MI is increased 3-to 6-fold, and the risk of any cardiovascular event is as high as 80%. 2 Because patients with a previous history of cardiovascular events are at high risk for a future MI,
more » ... sk for a future MI, 3 aggressive management, including risk factor modification, is mandatory in this patient group. 4-6 Considerable evidence indicates that a secondary prevention program to reduce cardiovascular risk factors can favorably affect cardiovascular mortality and morbidity. 7,8 Although there are many available studies from North America and Europe regarding the risk factors for recurrent MI after the recovery from AMI, [9] [10] [11] little is known concerning the Japanese population. 12 Racial differences, including genetic factors, life style, and the environmental circumstances of the patients, will affect the factors that accelerate coronary atherosclerosis and advance to subsequent MI, so we evaluated the risk factors of a recurrent MI in Japanese patients after recovery from the first AMI. 2000 within 48 h of developing chest pain and who were discharged after recovery. The diagnosis of AMI was established by the presence of 2 of the following 3 criteria: (1) elevation of serum creatine kinase (CK) more than triple the upper normal limit, (2) characteristic chest pain, or (3) ECG findings of ST-T change with evolution of the Q wave. Non-Q wave infarction was diagnosed by typical ST segment and/or T wave changes associated with serum CK elevation. All patients were in New York Heart Association functional class I or II at discharge. The patients were followed up at the hospital or by mail at 6 and 12 months, and 5 and 10 years after discharge, and follow-up data was available from more than 90% of patients at 1 year post discharge. Patients who died from an unknown cause were excluded. Because most of the patients who had a second MI were admitted to Iwakuni National Hospital, there was no apparent difficulty in obtaining information regarding the second cardiac event. Risk factors identified from the medical history, physical findings, laboratory data, ECG and chest X-ray were reviewed. The standard 12-lead ECG was recorded on admission, 3 h later and then once a day for 4 days. The ECG in leads CM5 and NASA was continuously monitored for at least 48 h after admission. The location of the infarction was divided into 2 groups based on involvement of the left ventricular anterior wall: (1) anterior and (2) other. Serum low-density lipoprotein-cholesterol (LDL-C) concentration was calculated from the values of total cholesterol (TC) and high-density lipoprotein-holesterol (HDL-C) and triglyceride, according to Friedewald's formula. 13 The laboratory data on admission, except for C-reactive protein (CRP), were used for analysis. The CRP concentration at discharge, instead of at admission, was used because the admission value was abnormally elevated as a result of the inflammatory nature of AMI. Little is known of the risk factors of recurrent myocardial infarction (MI) among Japanese patients who have survived their first MI. The risk factors for the second MI were studied in 808 of 1,042 consecutive patients who recovered from an acute MI in Iwakuni National Hospital. Multivariate logistic regression analysis revealed that only 3 of 21 variables measured were closely related with the recurrence of MI during a follow-up period of 3.2± 4.3 years: (1) transient atrial fibrillation (relative risk (RR) 3.16), (2) previous cerebrovascular accident (RR 3.05), and (3) dyslipidemia (RR 2.19). Of the parameters of dyslipidemia, a low ratio of high-density lipoproteinholesterol (HDL-C) to low-density lipoprotein-cholesterol (LDL-C) alone indicated subsequent MI. None of age, gender, location of the infarction, hypertension, diabetes mellitus, pulmonary congestion (Killip's class ≥2), peak serum creatine kinase activity, serum total-cholesterol, HDL-and LDL-cholesterol levels, nor smoking habit on admission was a statistically significant predictor for the second MI. The result suggests that more intensive treatment is needed for patients with the 3 risk factors. (Circ J 2002; 66: 877 -880)
doi:10.1253/circj.66.877 pmid:12381077 fatcat:bxqskgzfa5apjahh6lekmdknee