High-Sensitivity Cardiac Troponin and the Risk Stratification of Patients with Renal Impairment Presenting with Suspected Acute Coronary Syndrome
Background—High-sensitivity cardiac troponin testing may improve the risk-stratification and diagnosis of myocardial infarction, but concentrations can be challenging to interpret in patients with renal impairment and the effectiveness of testing in this group is uncertain.
Methods—In a prospective multi-center study of consecutive patients with suspected acute coronary syndrome, we evaluated the performance of high-sensitivity cardiac troponin I in those with and without renal impairment (estimated glomerular filtration rate <60mL/min/1.73m2). The negative predictive value (NPV) and sensitivity of troponin concentrations below the risk stratification threshold (5ng/L) at presentation were reported for a primary outcome of index type 1 myocardial infarction, or type 1 myocardial infarction or cardiac death at 30 days. The positive predictive value (PPV) and specificity at the 99th centile diagnostic threshold (16ng/L in women, 34ng/L in men) was determined for index type 1 myocardial infarction. Subsequent type 1 myocardial infarction and cardiac death were reported at 1 year.
Results—Of 4,726 patients identified, 904 (19%) had renal impairment. Troponin concentrations <5ng/L at presentation identified 17% of patients with renal impairment as low-risk for the primary outcome (NPV 98.4%, 95% confidence interval [CI] 96.0-99.7%; sensitivity 98.9%, 95%CI 97.5-99.9%), compared to 56% without renal impairment (P<0.001) with similar performance (NPV 99.7%, 95%CI 99.4-99.9%; sensitivity 98.4%, 95%CI 97.2-99.4%). The PPV and specificity at the 99th centile were lower in patients with renal impairment at 50.0% (95%CI 45.2-54.8%) and 70.9% (95%CI 67.5-74.2%) respectively, compared to 62.4% (95%CI 58.8-65.9%) and 92.1% (95%CI 91.2-93.0%) in those without. At 1 year, patients with troponin concentrations >99th centile and renal impairment were at greater risk of subsequent myocardial infarction or cardiac death than those with normal renal function (24% vs. 10%, adjusted hazard ratio 2.19, 95%CI 1.54-3.11).
Conclusions—In suspected acute coronary syndrome, high-sensitivity cardiac troponin identified fewer patients with renal impairment as low-risk and more as high-risk, but with lower specificity for type 1 myocardial infarction. Irrespective of diagnosis, patients with renal impairment and elevated cardiac troponin concentrations had two-fold greater risk of a major cardiac event compared to those with normal renal function, and should be considered for further investigation and treatment.
Clinical Trial Registration—URL: https://clinicaltrials.gov Unique Identifier: NCT01852123
- Received July 6, 2017.
- Revision received August 31, 2017.
- Accepted September 18, 2017.
Circulation is published on behalf of the American Heart Association, Inc., by Wolters Kluwer. This is an open access article under the terms of the Creative Commons Attribution License (http://creativecommons.org/licenses/by/3.0/), which permits use, distribution, and reproduction in any medium, provided that the original work is properly cited.