Higher serum uric acid levels predict higher mortality in heart attack patients
Delhi: Higher the serum uric acid levels, higher is the mortality associated with acute myocardial infarction (heart attack), a recent study in the Journal of the Association of Physicians of India has found.
According to the study, serum uric acid level is significantly associated with Killip class, left ventricular failure and mortality i.e. higher the serum uric acid, higher the Killip class, more severe left ventricular dysfunction and higher the mortality. The Killip classification is a system used to stratify the severity of left ventricular dysfunction and determine the clinical status of post-MI patients.
Coronary artery disease (CAD) is the leading cause of mortality and morbidity in present days. In the US approximately 525,000 experience a new acute myocardial infarction (AMI) and 190,000 experience recurrent AMI each year. More than half of AMI related deaths occurs before the individual reaches to hospital.5 In hospital mortality is approximately 6%. 1year mortality rate after AMI is about 15%.
There are some markers indicating unfavourable prognosis in acute myocardial infarction. Uric acid is one of the markers that is being evaluated for research however, its role as a risk factor remains controversial.
Uric acid may impair kidney function by causing glomerular damage and preglomerular arteriosclerosis, ultimately results in arterial hypertension, which is highly predictive of mortality in patients with coronary artery disease or heart failure. It is a matter of controversy as to whether serum uric acid is an independent cardiovascular risk factor or rather it only represents a reinforcement of typical risk factors.
Niraj Kumar, DNB Resident, Department of Community Medicine, Dr. Baba Saheb Ambedkar Medical College & Hospital, New Delhi, and colleagues conducted an observational prospective study to determine the association between serum uric acid level and severity of left ventricular failure assessed clinically by Killip classification and to know the correlation between serum uric acid level and ejection fraction assessed objectively by 2D echocardiography
For the purpose, the researchers enrolled 100 patients of acute myocardial infarction. Physical examination with special reference to Killip classification, ECG, 2D- Echocardiogram, Serum uric acid and all routine investigations were carried out on 0, 3rd and 7th day. Serum uric acid and Killip class and ejection fractions on day 0, day 3 and day 7 were compared.
Key findings of the study include:
- majority of the patients were in the age group of >50 years (68%).
- There was statistically significant increase in uric acid levels with increasing Killip class on day 0, day 3 and day 7.
- Mean serum uric acid level was 4.4 mg/dl in Killip class I, 7.01 mg/dl in class II, 8.29 mg/dl in class III, and 9.87 mg/ dl in class IV on day 0; 4.46 mg/dl in Killip class I, 7.09 mg/dl in class II, 8.53 mg/ dl in class III, and 9.43 mg/dl in class IV on day 3; 4.72 mg/dl in Killip class I, 6.62 mg/dl in class II, on day 7.
- There was a statistically significant negative correlation between serum uric acid levels and ejection fraction at all the three occasions i.e. day 0, day 3 and day 7.
"As serum uric acid is an economical biomarker that is readily, quickly and reliably obtainable, it can be one of the predictable prognostic indicators in acute myocardial infarction. Further studies on larger cohort are needed to establish these findings," concluded the authors.
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