The Importance of Serum Uric Acid Levels and Killip Classification in Predicting Prognosis of Acute Myocardial Infarction

Abstract

BACKGROUND The study was conducted in an attempt to correlate serum uric acid levels with Killip class i.e. severity of heart failure in patients with acute myocardial infarction and to assess any influence of serum uric acid levels on predicting prognosis in patients with acute myocardial infarction. Ischaemic heart disease, particularly acute myocardial infarction is one of the leading causes of death across the world accounting for 12.7 % of global mortality. Low and middle-income countries are facing 80 % of the global burden of ischaemic heart disease death. Since the pathophysiology of acute myocardial infarction is complicated, proper risk stratification is essential for appropriate management and better outcome. Serum uric acid levels (SUA) have been correlated with coronary artery calcification and atherosclerosis. High SUA levels also have been identified as a risk marker for cardiovascular disease development, progression and mortality. METHODS The study design was a one-year cross-sectional study. 100 patients admitted with acute myocardial infarction within one day of the start of symptoms in the Department of Cardiology & Medicine were included from September 2018 to September 2019. In this study, patients with known causes of elevated uric acid levels (chronic kidney disease, gout, haematological malignancy, hypothyroidism, metabolic syndrome, myeloproliferative disease, lymphoproliferative disease, drugs– pyrazinamide, diuretics, ethambutol, ethanol, malignancy, G6PD deficiency and psoriasis) were included. Patients on drugs which raise serum uric acid e.g., salicylates (2 gm / d, hydrochlorothiazide, pyrazinamide), and chronic alcoholics were not included. Patients were further subjected to investigations like serum uric acid, ECG, 2D echo and other routine investigations. Urine albumin levels, troponin I, chest x-ray, fundoscopy, and fasting lipid profile were done. Investigation reports were analysed with the clinical profile and the data was compiled and appropriate statistical test was applied. RESULTS There were more cases of myocardial infarction above 40 years as compared to below 40 years of age and males (69 %) were more as compared to females (31 %) with the commonest presentation as chest pain. Majority of the patients had inferior wall myocardial infarction (IWMI) (40 %) and most (91 %) of the patients had left ventricular (LV) dysfunction (mild, moderate and severe). More patients with Killip class III and IV had abnormal uric acid levels as compared to class I, and II. Among 27 patients who expired, 23 were in Killip class III and IV (13 in Killip class III and 10 in class IV) and the mean serum uric acid levels of expired patients were elevated on all the 3 days with maximum elevation on day 1. CONCLUSIONS Patients with higher Killip class had higher levels of serum uric acid in comparison to patients of lower Killip class. Serum uric acid level in association with Killip class is a good predictor of the severity of heart failure and short-term mortality after myocardial infarction.