5-Minute Journal Club: High-Sensitivity Cardiac Troponin and the Risk Stratification of Patients with Renal Impairment Presenting With Suspected Acute Coronary Syndrome

Author: Dr. Eric Moyer

Background:

It is often difficult to interpret high-sensitivity cardiac troponin values in patients with renal impairment given the reduced clearance by the kidneys. This study attempts to quantify ways to risk stratify patients with renal impairment and suspected acute coronary syndrome using high-sensitivity cardiac troponins.

Design:

• Prospective, multicenter study
• Inclusion: All patients in whom cardiac troponin was ordered for suspected ACS
• Exclusion:
  • Diagnosed with STEMI
  • Admitted previously during the study period
  • Those unable to have hospital records linked with outcomes
• Primary outcome: type 1 myocardial infarction, cardiac death at 30 days
• Other outcomes evaluated: Readmission with type 1 myocardial infarction, cardiac death, and all-cause death at 1 year

Takeaways/Results:

1. Patients with and without renal impairment with an initial troponin of <5 ng/L at presentation can be deemed low risk for ACS.
2. Patients with renal impairment are more likely to present with cardiac troponin concentrations >99^th percentile and myocardial infarction compared to those without impairment, however, the PPV, likelihood ratio and specificity of cardiac troponin concentrations >99^th percentile for type 1 myocardial infarction were lower in those with renal impairment.
3. Patients with cardiac troponin concentrations >99th percentile and renal impairment had a 2-fold greater risk of subsequent type 1 myocardial infarction or cardiac death at 1 year

Discussion:

• Limitations:
  • Only a small population in the study were on dialysis. Caution must be taken in this patient population
  • Predominantly white population (93%)
  • Limited to a single high-sensitivity cardiac troponin I assay
• The study affirms the use of a lower threshold of 5 ng/L to identify those low-risk for ACS in all patients, irrespective of renal disease. Our high-sensitivity cardiac troponin algorithm at Rush uses the same cutoff and I feel even more confident in discharging patients who have an initial troponin <5 ng/L from the ED. However, if the initial troponin is >99^th percentile, it is less clear whether this indicates acute coronary syndrome in those with renal impairment. Care must be taken in this patient population because they have a 2-fold greater risk of cardiac death or myocardial infarction at 1 year than those without renal impairment. This observation supports those who suggest that elevations in cardiac troponin concentrations in kidney disease reflect underlying cardiovascular disease, rather than impaired renal clearance. It is difficult to say whether this means all patients with renal impairment and a high-sensitivity troponin >99^th percentile should be admitted for further investigation, but I would exercise more caution and think twice about discharge.

Take Away:

High-sensitivity troponin values aren’t as sensitive or specific for ACS in patients with renal impairment, but care should be taken in patients with elevated values given their increase risk.

Citation:

Miller-Hodges E, Anand A, Shah ASV, Chapman AR, Gallacher P, Lee KK, Farrah T, Halbesma N, Blackmur JP, Newby DE, Mills NL, Dhaun N. High-Sensitivity Cardiac Troponin and the Risk Stratification of Patients With Renal Impairment Presenting With Suspected Acute Coronary Syndrome. Circulation. 2018 Jan 30;137(5):425-435. doi: 10.1161/CIRCULATIONAHA.117.030320. Epub 2017 Oct 4. PMID: 28978551; PMCID: PMC5793996.