Background: Although troponin is the preferred biomarker to indicate acute myocardial infarction, little is known about the implications of elevated troponin in the absence of plaque rupture.
Study design: Retrospective cohort study.
Setting: Tertiary academic hospitals in the United Kingdom.
Synopsis: The records of 257,948 hospitalized patients with a measured troponin value were analyzed over 8 years. Overall, a positive troponin conferred three times the mortality risk, with the strongest association in those aged 18-29 (hazard ratio, 10.6), compared with those aged 90 or older (HR, 1.5). It may be that those younger patients, for whom a troponin was ordered, are a fundamentally different, sicker cohort when compared with their peers and in contrast to the older patients for whom a troponin is widely sent. Furthermore, mortality increases with age, and a positive troponin may not impact the mortality rate as much as it does in a younger patient. Mortality was heavily concentrated in the first 3 months after discharge. The authors noted an inverted U-shaped relationship between troponin level and mortality in patients admitted to the hospital and in those with acute coronary syndrome. There was a direct positive correlation between troponin value and mortality until a certain threshold was crossed, at which point mortality decreased abruptly. This mortality drop off may result from a higher troponin leading to an increased likelihood of catheterization, a procedure that improves outcomes. Because of this study’s retrospective nature, one cannot establish a causal relationship between troponin values and mortality. However, it highlights the need to study the mechanism for these outcomes across the age spectrum and to ensure close monitoring of elevated troponin values on an outpatient basis.
BOTTOM LINE: Elevated troponin levels are associated with an increased risk of mortality in all age groups and require close outpatient follow-up.
Citation: Kaura A et al. Association of troponin level and age with mortality in 250,000 patients: Cohort study across five UK acute care centres. BMJ. 2019;367:I6055. doi: 10.1136/bmj.l6055.
Dr. Bhasin is a hospitalist at Northwestern Memorial Hospital and Lurie Children’s Hospital and assistant professor of medicine, Feinberg School of Medicine, all in Chicago.