Quantitative troponin elevation does not provide incremental prognostic value beyond comprehensive risk stratification in patients with non-ST-segment elevation acute coronary syndromes

Non-alcoholic fatty liver disease and outcomes in persons with acute coronary syndromes: insights from the GRACE-ALT analysis

OBJECTIVE

Non-alcoholic fatty liver disease (NAFLD) is associated with a higher risk of cardiovascular disease, but no data exist about the relation between NAFLD and adverse outcomes in persons with acute coronary syndromes (ACS). We evaluated elevated serum alanine aminotransferase (ALT) as a marker of NAFLD, in association adverse outcomes following ACS.

METHODS

We conducted a retrospective cohort study of participants enrolled in the Global Registry of Acute Coronary Events (GRACE) admitted for ACS to St Michael's Hospital, Toronto, between 1999 and 2007. Multivariable linear regression was used to determine the change in maximum measured cardiac troponin I (cTnI) per each 1 IU/l increase in serum ALT concentration. The association between an elevated ALT >90th centile, and adverse outcomes in-hospital and at 6 months were calculated using multiple logistic regression analyses, adjusting for age, sex, body mass index, serum creatinine, glucose, triglycerides and LDL-C, as well as chronic statin or other lipid-lowering agent use.

RESULTS

528 participants were included. Each 1 IU/l increase in ALT was associated with an increase in maximum measured cTnI of 0.16 µg/l (95% CI 0.10 to 0.22). An elevated ALT concentration >90th percentile was associated with a maximum measured cTnI in the highest quartile (adjusted OR 7.07, 95% CI 1.83 to 27.37). An elevated ALT >90th percentile was also significantly associated with all-cause mortality in-hospital, and up to 6 months after discharge (adjusted OR 8.96, 95% CI 3.28 to 24.49).

CONCLUSIONS

NAFLD, determined by an elevated serum ALT, is associated with a higher risk of adverse outcomes in persons with ACS. Whether ALT is a valid and independent prognostic marker in ACS remains to be determined.

An assessment of the concentration-related prognostic value of cardiac troponin I following acute coronary syndrome

In 2004 the British Cardiac Society redefined myocardial infarction by cardiac troponin I (cTnI) concentration: ≤ 0.06 μg/L (unstable angina), >0.06 to < 0.5 μg/L (myocardial necrosis), and ≥ 0.5 μg/L (myocardial infarction). We investigated the effects of this classification on all-cause mortality in 1,285 patients from the Evaluation of the Methods and Management of Acute Coronary Events (EMMACE)-2 registry. There were 528 deaths (6.6-year all-cause mortality 41.1%). Survival was greatest in the cTnI ≤ 0.06-μg/L subgroup at 30 days (p = 0.005), 6 months (p = 0.015), 1 year (p = 0.002), and 6.6 years (p = 0.045). After adjustment there was no significant difference in survival between the cTnI >0.06- to < 0.5-μg/L and ≥ 0.5-μg/L subgroups. Increased mortality (hazard ratio, 95% confidence interval) was associated with ages 70 to 80 years (2.58, 1.17 to 3.91) and >80 years (3.30, 3.50 to 5.06), peripheral vascular disease (1.50, 1.16 to 1.94), heart failure (1.36, 1.05 to 1.83), diabetes mellitus (1.68, 1.36 to 2.07), severe left ventricular systolic dysfunction (1.50, 1.00 to 2.21), and creatinine per 10 μmol/L (1.65, 1.02 to 1.08), whereas ages 50 to 60 years (0.55, 0.32 to 0.96), β blockers (0.53, 0.44 to 0.64), aspirin (0.80 0.65 to 0.99), angiotensin-converting enzyme inhibitors (0.67, 0.56 to 0.80), statins (0.73, 0.59 to 0.90), and revascularization (0.33, 0.12 to 0.92) were associated with a lower risk of death. In conclusion, although quantitative evaluation of cTnI concentration in patients with acute coronary syndrome with cTnI > 0.06 μg/L was associated with no added prognostic information, the dichotomization of patients by cTnI status ("positive" and "negative") facilitates acute coronary syndrome risk stratification.