Background:The clinical significance of mildly elevated troponins in patients presenting to the emergency room (ER) with atrial fibrillation (AF) is not well understood. Hypothesis: We hypothesized that mildly elevated troponin in these patients is associated with adverse cardiovascular outcomes. Methods: In a multi-center, retrospective study, 662 patients with AF were divided into 3 groups based on troponin levels: group 1, mildly elevated; group 2, normal; and group 3, troponin not measured. Primary outcome was the combined endpoint of all-cause mortality and myocardial infarction (MI) at one year. Results: Levels of TnI were measured in 503 (76%) patients. They were elevated in 220 patients (33%, group 1; mean, 0.56 ng/mL), normal in 283 patients (43%, group 2), and not measured in 159 patients (24%, group 3). Significantly more cardiac testing was done at index hospitalization in group 1 (50%) compared with groups 2 and 3 (28% and 29%, P ≤ 0.001) and in the following year (29%, vs 20% and 17%, P = 0.02). Group 1 had more positive tests (62%) compared with groups 2 and 3 (25% and 43%, P ≤ 0.001). Group 1 had a significantly higher occurrence of the primary endpoint (22%, vs 10% and 15%, P = 0.002), driven primarily by a higher incidence of MI in group 1 (7%, vs 1% and 2%, P = 0.001). Conclusions: Troponin levels are routinely checked in a majority of patients presenting to the emergency department with AF. Even mildly elevated TnI is associated with a greater incidence of coronary artery disease on diagnostic testing and a higher 1-year incidence of MI.

Introduction: Cardiac markers are frequently checked in patients presenting with atrial fibrillation (AF) and rapid ventricular rate (RVR). Clinical significance of mild troponin elevation in this setting and clinical value of this practice is not well known. It has been suggested that mild troponin elevation in this setting represents rate related demand ischemia and not ACS. Hypothesis: We hypothesized that measuring Troponin in AF/ RVR without signs/ symptoms of myocardial infarction has low yield and limited clinical value in predicting cardiovascular events. Method: Multi-center, retrospective cohort study of 452 subjects (age 67±14, M:F=4:1) presenting with AF/ RVR between 2000 and 2006. Occurrence of MI at one year after discharge was primary outcome. Results: Of all cases presenting with A fib/ RVR, Troponin was checked in 351 cases (77.7%). Of these 197 (age 70±11, M:F=7.1) had elevated Troponin(group-I) and 154 (age 61±16, M:F=1.1) had a normal Troponin (group-II) (1.4±5.3 vs 0.02±0.01 ng/ml, P=0.003). Group-I was older with more renal failure compared to group-II (P=0.0001, 0.0001, 0.0002 respectively). However, there was no difference in the rate of diabetes, anemia and symptom of chest pain at the time of presentation (P=0.9, 0.07 and 0.058 respectively). There was no significant difference in ventricular rate (123+31vs 123+33, P=0.3), duration of symptoms (61±186.6 vs 30.3±46.1 h , P=0.2), and ST-T changes (38(21%) vs 38 (28%) P=0.8) between two groups. During hospitalization, 76(38.6%) stress tests were performed on subjects in group-I vs. 48(31%) in group-II (p=0.17). These stress tests led to 37(48.7%) vs 12(25%) coronary angiographies (P=0.013). In group-I at one year follow up, 15 (7%) of subjects developed MI, but none in group-II. Based on these data, Troponin has sensitivity, specificity, positive and negative predictive values of 84.6%, 27.8%, 29.7% and 83.3% respectively for detecting coronary disease in A Fib weith RVR and 100%, 45.8%, 7.6% and 100% respectively for occurrence of MI in one year. Conclusion: Even mild troponin elevation in the setting of AFib with RVR predicts a significant increase in risk of MI at 1 yr. A normal Troponin in this setting is predictive of a favorable cardiovascular outcome at one year.