High-Sensitivity Cardiac Troponin I Levels Below 99th Percentile Upper Reference Limit in Patients Presenting with Suspicion of Acute Coronary Syndrome (ACS) in Emergency Department at a Tertiary Care Hospital in Karachi, Pakistan.

INTRODUCTION

Troponin I levels are biomarkers of choice for diagnosis of acute myocardial infarction (AMI). However, prognostic significance of values below the 99th percentile upper reference limit (URL) in patients presenting with symptoms suggestive of Acute coronary syndrome (ACS) need further evaluation.

AIM

The objectives of the study were to find the association of High sensitivity (hs)-Troponin I values below 99th percentile URL with age and the Emergency Department (ED) outcome, to determine single cut-off for safe discharge of these patients from the ED and to determine the 30-day outcome of the patients admitted under cardiac speciality.

METHODS

This is a retrospective study of patients presenting with suspicion of ACS in the ED between January 2019 till April 2021 and hs-Troponin I values below 99th percentile URL.

RESULTS

Among 15,441 patients, 8034 (52%) were males and 7407 (48%) were females. 9677 (63%) of the patients had hs-Troponin I values < 5 ng/L while 5764 (37%) had values between 5 ng/L and 99th percentile URL. Higher hs-Troponin I values were associated with a worse ED outcome. Serial troponin I levels were performed in only 2.4% of the cohort. Receiver operating characteristics for ACS demonstrated an AUC of 0.84 at a cut off value of 12.75 ng/L, with sensitivity (76.9%) and specificity was 75.1%. The 30-day outcome of the patients admitted under cardiac speciality revealed no mortality in either group.

CONCLUSION

An overall single cut-off value of 12.75 ng/L can be used in our population for ruling our ACS provided it is unaccompanied by other supportive clinical and ECG findings.