Troponin and Cardiac Events in Stable Ischemic Heart Disease and Diabetes

Amanda Breakey, Mercer University College of Pharmacy

Cardiac troponin (cTn) is an essential biomarker of cardiac injury and should be measured in all patients presenting with acute coronary syndrome (ACS), as stated in the practice guidelines set forth by the American College of Cardiology/American Heart Association (ACC/AHA). The ACC/AHA states that the presence of elevated cTn in patients with ACS has demonstrated a strong association with poorer outcomes, however, through detection of this biomarker, physicians are better able to identify those patients that would likely benefit from an early invasive management strategy.1 According to a review published in the Internal Journal of Angiology, cTn levels have demonstrated extreme sensitivity and specificity for myocardial damage, regardless of the etiology. Additionally, authors state that elevated cTn levels can occur in the absence of ACS.2 According to the American College of Cardiology Task Force (ACCF), recent development of high-sensitivity troponin assays has allowed for increased diagnostic and prognostic accuracy in diseases not limited to ACS, including chronic stable coronary artery disease without left ventricular systolic function.3

Title: Troponin and Cardiac Events in Stable Ischemic Heart Disease and Diabetes4
Design Retrospective, cohort; N= 2,285
Objective To evaluate the prognostic implications of high-sensitivity cardiac troponin levels among patients with stable ischemic heart disease and diabetes
Study Groups – Normal (< 14 ng/ liter) troponin T concentration group (n= 2,227)   – Abnormal (≥ 14 ng/ liter) troponin T concentration group (n= 897)
Methods Patients were selected as candidates for either percutaneous coronary intervention (PCI) or coronary artery bypass grafting (CABG).   Patients were then randomly assigned to prompt coronary revascularization plus intensive medical therapy (revascularization group) or intensive medical therapy alone (medical-therapy group).   Plasma samples were obtained at baseline and at 1-year follow-up and cardiac troponin T concentrations were measured using high-sensitivity electrochemiluminescence assays.
Duration 5 years
Primary Outcome Measure Composite death from cardiovascular causes, nonfatal myocardial infarction (MI), or nonfatal stroke
Baseline Characteristics
Characteristic Troponin T < 14 ng/ liter (n= 1,388) Troponin T ≥ 14 ng/ liter

(n= 897)

p value
Median age- yr. 61 64 < 0.001
Male sex- % 65.1 77.8 < 0.001
Race- % 0.006
White non-Hispanic 66.7 63.7
Black non-Hispanic 15.7 19.0
Hispanic 11.8 14.2
Asian non-Hispanic 5.1 2.7
Other non-Hispanic 0.6 0.6
Hypertension requiring treatment- % 80.7 85.2 0.006
History of MI- % 28.4 37.9 < 0.001
History of CHF requiring treatment- % 4.0 10.4 < 0.001
Median duration of diabetes mellitus- yr. 7.2 10.4 < 0.001
Chronic renal dysfunction -% 0.9 6.4 < 0.001
Median glycated Hgb- % 7.3 7.4 0.03
HDL cholesterol- mg/ dL 37 36 0.003
Triglycerides- mg/ dL 146.0 151.5 0.02
Median estimated GFR- ml/ min/ 1.732 80.3 69.6 < 0.001
Median NT-proBNP-   ng/ liter 93.0 280.2 < 0.001
Current medications- %
Insulin 23.2 35.0 < 0.001
Aspirin 89.4 86.1 0.02
Median myocardial jeopardy index score 41.0 46.0 0.001
Number of lesions with ≥ 50% stenosis- % < 0.001
0- 1 33.9 24.1
2- 3 41.9 40.8
> 3 24.3 35.1
Number of vessels with lesions with ≥ 50% stenosis- % < 0.001
1 41.4 31.7
2 35.4 36.4
3 23.2 31.9
LVEF < 50%- %
Any ECG abnormality- % 48.6 50.5 < 0.001
CABG revascularization stratum- % 30.9 35.9 0.01

MI= myocardial infarction, CHF= congestive heart failure, Hgb= hemoglobin, HDL= high-density lipoprotein, GFR= glomerular filtration rate, NT-proBNP= N-terminal pro-brain natriuretic peptide, LVEF= left ventricular ejection fraction, ECG= electrocardiogram, CABG= coronary-artery bypass grafting

Results The 5–year rate of the composite end point was 27.1% among the patients who had had abnormal troponin T concentrations at baseline, as compared with 12.9% among those who had had normal baseline troponin T concentrations.
Adverse Events Common Adverse Events: N/A
Serious Adverse Events: N/A
Percentage that Discontinued due to Adverse Events: N/A
Study Author Conclusions The cardiac troponin T concentration was an independent predictor of death from cardiovascular causes, myocardial infarction, or stroke in patients who had both type 2 diabetes and stable ischemic heart disease.

Few studies have assessed cardiac troponin T as a marker of risk for patients with stable ischemic heart disease and diabetes. Researchers found that patients with elevated troponin T levels had an 85% greater risk of cardiovascular mortality, MI or stroke compared to those who did not have elevated troponin T levels. In order to better implicate these findings into clinical practice, further research needs to be done to help determine the source of elevated troponin T levels in stable heart disease patients.

References

  1. ACC/AHA Guidelines for the Managament of Patients with Unstable Angina and Non-ST-Segment Elevation Myocardial Infarction: Executive Summary and Recomendations. Circulation. 2000;102:1193-1209. doi:10.1161/01.CIR.102.10.1193.
  2. Skeik N, Patel DC. A review of troponins in ischemic heart disease and other conditions. Int J Angiol. 2007;16(2):53-8.
  3. ACCF 2012 Expert Consensus Document on Practical Clinical Considerations in the Interpretation of Troponin Elevations. J Am Coll Cardiol. 2012;60(23):2427-2463. doi:10.1016/j.jacc.2012.08.969.
  4. Everett BM, Brooks MM, Vlachos HE, et al. Troponin and Cardiac Events in Stable Ischemic Heart Disease and Diabetes. N Engl J Med. 2015;373(7):610-20.
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