Abstract 2658: Minor Elevations in Troponin I Predict Mortality in Patients With Atrial Fibrillation
Objectives: In patients with atrial fibrillation minor troponin elevation is regularly detected and attributed to a raise in wall stress during a rapid and/or irregular ventricular response. This minor elevation might be associated with long-term outcome. However, thus far the prognostic significance of minor elevations of troponin in a population with atrial fibrillation has not been investigated.
Methods: A retrospective study was conducted analysing all consecutive patients with atrial fibrillation admitted to the cardiology department of a peripheral hospital in 2005 and 2006. Patients with an ST-elevation myocardial infarction (STEMI) were excluded. Minor troponin elevation was defined as a detectablebut negative Troponin I level between >0.15 and 0.65 (IMMULITE, DPC), which is still below the 99th percentile. Troponin I levels were measured serially or at least 8 hours after the start of complaints. Study outcomes were all cause mortality (DEATH), a combined endpoint of all cause mortality and myocardial infarction (DEATH/MI) or all major adverse cardiac events (MACE: all cause mortality, myocardial infarction or revascularisation).
Results: Of 444 patients who were screened, 16 patients had an STEMI, 7 were lost to follow-up and 19 patients did not have troponin I measured, leaving 407 patients to include in the study. The mean duration of follow-up was 665 days. Of these 407 patients, 80 (20%) had a minor elevated troponin I level and 77 (19%) patients had a positive troponin I (0.65 or higher). A minor elevation in troponin I level was a strong univariate predictor of DEATH (hazard ratio [HR] of 2.26, 95% confidence interval [CI]: 1.45 to 3.56) as well as of DEATH/MI (HR: 2.27, 95% CI: 1.45 to 3.56) and MACE (HR: 2.35, 95% CI: 1.42 to 3.64). In a multivariate Cox model minor troponin I elevation together with a history of heart failure and age were the sole predictors of DEATH, DEATH/MI and MACE (HR: 1.85, 95% CI: 1.024 to 3.33, p=0.041 for DEATH; HR: 1.75, 95% CI: 1.00 to 3.06, p=0.048 for DEATH/MI; HR: 2.02, 95% CI: 1.18 to 3.48, p=0.011 for MACE).
Conclusions: Minor elevations in troponin I level on hospital admission are an important predictor of mortality and cardiac events in patients with atrial fibrillation and might be useful for risk stratification.