Significance of Elevated Troponin Levels in Patients Admitted with Atrial Fibrillation

Introduction:
Atrial fibrillation (AFib) is the most prevalent arrhythmic disorder worldwide. Patients with AFib often present with concomitant acute coronary syndrome (ACS), or as its actual presentation. In both troponin rise may occur. Therefore, it is unclear how to use and interpret elevated serum troponin levels, as it is often misleading.

We aimed to define characteristics and values of troponin at this clinical challenge predicting it is a consequence of ACS, or AF by itself.

Methods:
Clinical and laboratory characteristics of 166 consecutive patients admitted with a diagnosis of all subtypes of AFib during 2014, were retrospectively collected, in whom no ACS was suspected on admission. Serum troponin levels on admission and up-to 12 hours were analyzed. Concomitant ACS was diagnosed clinically or when in doubt by, subsequent coronary angiography (CAngio) done during the index admission.

Results:
In 143 patients out of 166 (84 males and 82 females, age 63.5±16.57 and 71.6±11.64 respectively) ACS was ruled out on clinical grounds and ECG assessments. In the remaining 23 patients, a subsequent CAngio was needed to rule out ACS that was eventually confirmed in 10 patients. Troponin dynamics (% change/hour) were found to be the most significant predictor for ACS in patients with AFib and elevated troponin (median change ACS=50%/hour, non-ACS=3%/hour, p=0.0103). History of congestive heart failure (CHF) and male gender were also predictive of ACS.

Conclusion:
In patients presenting with AFib and rising troponin levels not suspected as having an ACS on admission, accelerated troponin dynamics (>50% level increase per hour) was found to be the strongest predictor of a concomitant ACS. This finding may help in daily decision making whether to proceed to CAngio, or not, if the rising troponin is merely secondary to AFib alone.