I read with great interest the article by Bardají et al.1 In their study, the authors reported that patients with elevated troponin levels and no diagnosis of acute coronary syndrome (ACS) had higher mortality than patients with negative troponin without ACS, and had a similar prognosis to patients with ACS. In this article, I would like to emphasize some confusing factors about diagnosis in patients with elevated troponin levels and without ACS in that study. Firstly, in the study by Bardají et al,1 the authors reported 9 patients with chest pain, 6 patients with syncope, and 8 patients with other diagnoses in the group of patients with elevated troponin levels and without ACS. To our knowledge and according to current guidelines,2 these 3 diseases are not possible non-ACS causes of troponin elevation. Therefore, the authors should comment on the mechanism of troponin elevation in these patient subgroups and the reasons for potentially false-positive troponin elevation. Secondly, the cause of troponin elevation was tachycardia in 25 patients and bradyarrhythmia in 6 patients in the group of patients with elevated troponin levels and without ACS. Tachycardia and bradyarrhythmia are possible causes of non-ACS troponin elevation. However, it is known that they can occur during ACS and can be the only sign of ACS. In particular, ventricular tachycardia and atrioventricular blocks can be associated with ACS. Therefore, the authors should comment on the types of tachycardia and bradycardia and their possible relationship with ACS to eliminate misdiagnosis. Finally, the cause of troponin elevation was defined as heart failure in 55 patients in the non-ACS group. Ischemic heart disease may present as ACS in the acute phase and heart failure in the chronic phase.3 In addition, it is known that acute heart failure may be the presentation of ACS or can develop during hospitalization in non-ST-segment elevation ACS.4 In the study by Bardají et al,1 there are no data on the time to onset of heart failure symptoms. The authors should comment on the classification of heart failure patients and its possible relationship with ACS.

In conclusion, patients with elevated troponin levels and without ACS may have poor prognosis due to concomitant systemic diseases. Patient classification as ACS or not may need further examination in the study by Bardaji et al.1