Abstract 4012: Mild Troponin Elevation In subjects Presenting With Atrial Fibrillation With Rapid Ventricular Rate Is Associated With Adverse Cardiovascular Outcomes
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.