The initial anion gap is a predictor of mortality in acute myocardial infarction.
OBJECTIVE
To determine the relationship between the anion gap and outcomes in patients with acute myocardial infarction.


METHODS
We assessed the relationship between the initial anion gap and in-hospital outcomes among consecutive acute myocardial infarction patients admitted to a single coronary care unit. The anion gap was calculated as [sodium-(chloride+CO2)]. Anion gap>12 was considered to represent anion gap acidosis.


RESULTS
Complete data were available for 773 patients. Anion gap acidosis on admission was found in 90 patients (12%), and was more common among older patients (P=0.02), women (P=0.008), non-whites (P=0.04), and patients with diabetes (P=0.03), chronic renal failure (P<0.001), a lower glomerular filtration rate (P<0.001), and cardiogenic shock (P<0.001). In-hospital death occurred in 33% of patients with initial anion gap acidosis compared with 8% in those with a normal anion gap (P<0.001). On multivariate analysis, the presence of an initial anion gap acidosis was associated with the risk of death (odds ratio 4.2, 95% confidence interval 2.3-7.5, P<0.001), independent of other data available at the time of admission. The addition of ejection fraction to the model significantly attenuated this association.


CONCLUSIONS
The admission anion gap provides important incremental information for initial risk stratification in acute myocardial infarction.
Sahu
Anurag
A
Washington Hospital Center, Washington, District of Columbia 20010, USA.
Cooper
Howard A
HA
Panza
Julio A
JA
D000136:Acid-Base Equilibrium; D000138:Acidosis; D000208:Acute Disease; D000368:Aged; D003325:Coronary Care Units / Q000706:statistics & numerical data; D004219:District of Columbia; D005260:Female; D017052:Hospital Mortality; D006801:Humans; D008297:Male; D008875:Middle Aged; D009203:Myocardial Infarction / Q000401:mortality / Q000503:physiopathology*; D011379:Prognosis; D016896:Treatment Outcome