High Cardiac Troponin Levels Predict Mortality in CAP

In patients hospitalized with community-acquired pneumonia, elevated cardiac troponin T is a strong predictor of mortality.
In patients hospitalized with community-acquired pneumonia, elevated cardiac troponin T is a strong predictor of mortality.

Elevated cardiac troponin T (cTnT), a dependable marker for myocardial infarction,1,2 is also strongly prognostic of cardiac mortality observed in association with community-acquired pneumonia (CAP), according to a study by Vestjens et al, recently published in Respirology.3 Cardiac troponin T (cTnT) is a cardiac regulatory protein with high sensitivity and specificity to cardiac muscle enzyme measurements that quantify cardiac muscle damage.4

In the current study, the investigators retrospectively extracted data from 295 hospitalized participants in an earlier randomized placebo-controlled trial of adjunctive dexamethasone treatment for CAP conducted in The Netherlands from November 2007 to September 2010. The cohort was comprised of 167 men and 128 women (median age 67) diagnosed with CAP; the most common comorbid conditions included smoking (27.1%), heart disease (16.6%), diabetes mellitus (14.2%), chronic renal failure (9.2%), and neoplastic diseases (6.4%).

Of the study participants, 132 (44.7%) had elevated cTnT levels of 14 ng/L or greater, designated as “elevated,” measured from blood samples taken from the participants upon admission. Overall, short-term survival was poor in this group: 15 out of 16 patients who died soon after admission were among the patients with elevated cTnT levels, 19 patients (6.4%) died before day 30, and another 49 patients (16.4%) died within 1 year of hospitalization.

High cTnT levels had a negative impact on both morbidity and mortality that increased exponentially at the highest levels. Intensive care unit (ICU) admission went from 3.1% and 4.7% at 14 ng/L and 14-28 ng/L, respectively, to 11.8% at >28 ng/L. Early death in the hospital increased from 0.6% and 1.6% to 20.6%, and 30-day mortality rose from 0.6% and 1.6% to 22.1%. No other factor or comorbidity was so significantly associated with 30-day mortality. At 1 year, mortality increased from 3.1% at levels below 14 ng/L to 12.5% at 14-28 ng/L, and 52.9% at 28 ng/L.

This study was the first to assess long-term mortality, which was 32% from all causes at 4.1 years post-hospitalization, and directly associated with high cTnT upon admission. The impact of the highest cTnT levels on long-term mortality was most striking: increasing from 6.1% below 14 ng/L to 13.7% at 14-28 ng/L, and 72.1% at 28 ng/L and above.

Elevated cTnT was strongly prognostic of both short- and long-term mortality in CAP compared with other measures used to predict survival in CAP, including the Pneumonia Severity Index (PSI) and CURB-65 (confusion, urea, respiratory rate, blood pressure in patients older than  65). Patients with high cTnT were older and had more comorbidies, captured as part of the PSI rating; therefore, patients with a higher PSI also had higher cTnT levels. The use of antiplatelet therapy also increased long-term mortality in the presence of even moderately elevated cTnT levels (≥14 ng/L). One surprising trend was that cTnT was less likely to be elevated in smokers in the study than nonsmokers.

The investigators suggested that elevated cTnT in patients admitted with CAP warrants diagnostic consideration of cardiac risks and modified treatment plans to reduce risks of all-cause mortality.

References

  1. Braunwald E , Antmann EM, Beasley JW, et al. ACC/AHA guidelines for the management of patients with unstable angina and non ST elevation myocardial infarction: executive summary and recommendations. A report of the American College of Cardiology/American Heart Association task force on practice guidelines (Committee on the Management of Unstable Angina). Circulation. 2000;102:1193-1209. doi:10.1161/01.CIR.102.10.1193
  2. Bertrand ME, Simoons ML, Fox KA, et al. Management of acute coronary syndromes: acute coronary syndromes without persistent ST segment elevation. Recommendations of the Task Force of the European Society of Cardiology. Eur Heart J. 2000;21:1406-1432. doi:10.1053/euhj.2000.2301
  3. Vestjens SM, Spoorenberg SM, Rijkers GT, et al; Ovidius Study Group. High-sensitivity cardiac troponin T predicts mortality after hospitalization for community-acquired pneumonia [published online February 21, 2017]. Respirology. doi:10.1111/resp.12996
  4. Collinson PO, Boa FG, Gaze DC. Measurement of cardiac troponins. Ann Clin Biochem. 2001;38:423-429. doi:10.1177/000456320103800501
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