Abstract 8734: The Utility of Troponin I in Two Cohorts of Cardiac Patients: Implications for Clinical Practice
Background: Minor elevations in troponin I are common among patients with chronic coronary artery disease (CAD) and those with new supraventricular tachyarrhythmia (SVT). These troponin I elevations are often attributed to an acute coronary syndrome (ACS). However, minor elevations in troponin I may be present for other reasons, such as demand ischemia. Our aim was to observe the prevalence of troponin I elevations in patients with: 1) new onset atrial fibrillation (A-fib), flutter (A-flutter) or SVT and 2) known CAD following exercise, and to assess the hypothesis that troponin I elevations in these settings would not be indicative of ACS.
Methods: This study included two components. First, a retrospective review of 740 charts of patients with new onset A-fib, A-flutter or ectopic SVT presenting to the Danbury Hospital Emergency Department between July 2009 and July 2010. Excluded were 45 patients with symptoms and EKG changes indicating ACS on admission. Second, a separate sample of 75 patients with known CAD presenting to the Danbury Hospital Cardiology Clinic for follow-up imaging stress tests were recruited. Eligible patients underwent a stress test and perfusion imaging and had one troponin I sample drawn prior to the stress test and a second at the completion of all imaging four hours later.
Results: Among patients with new A-fib, A-flutter and SVT, 31.9% had minor elevations in troponin I levels (values ranged from 0.05-1.0 ng/mL). In those with elevation, 64% had no documented CAD. In addition, for those with elevation, 78.4% had new onset A-fib, 11.3% had new onset A-flutter and 10.4% had new onset SVT. In the separate cohort of patients with CAD who underwent stress testing, 38.7% had troponin elevation following exercise. A total of 50.7% of these patients had no evidence of ischemia by EKG and perfusion and 54.7% had a Duke Treadmill score greater than or equal to 5.
Conclusion: For patients with chronic CAD subject to physical stress or those with new onset A-fib, flutter or SVT, small elevations in troponin I are fairly common, and often do not indicate ACS. In a cost containment environment, expensive therapy and testing of these patients may be unnecessary.
- © 2011 by American Heart Association, Inc.