Prognostic implications of troponin I elevation in emergency department patients with tachyarrhythmia

BACKGROUND: Tachyarrhythmias are very common in emergency medicine, and little is known about the long-term prognostic implications of troponin I levels in these patients. HYPOTHESIS: This study aimed to investigate the correlation of cardiac troponin I (cTnI) levels and long-term prognosis in patients admitted to the emergency department (ED) with a primary diagnosis of tachyarrhythmia. METHODS: A retrospective cohort study was conducted between January 2012 and December 2013, enrolling patients admitted to the ED with a primary diagnosis of tachyarrhythmia and having documented cTnI measurements. Clinical characteristics and 5-year all-cause mortality were analyzed. RESULTS: Of a total of 222 subjects with a primary diagnosis of tachyarrhythmia, 73 patients had elevated levels of cTnI (32.9%). Patients with elevated cTnI levels were older and presented significantly more cardiovascular risk factors. At the 5-year follow-up, mortality was higher among patients with elevated cTnI levels (log-rank test P < 0.001). In the multivariable Cox regression analysis, elevated cTnI was an independent predictor of all-cause death (hazard ratio, 1.95, 95% confidence interval: 1.08-3.50, P = 0.026), in addition to age and prior heart failure. CONCLUSION: Patients admitted to the ED with a primary diagnosis of tachyarrhythmia and high cTnI levels have higher long-term mortality rates than patients with low cTnI levels. cTnI is thus a biomarker with predictive capacity for mortality in late follow-up, conferring utility in the risk stratification of this population.