Letter to the Editor New-onset atrial fibrillation may be a more important predictor of cardiac mortality in acute myocardial infarction patients than preexisting atrial fibrillation ☆ , ☆☆ Itsuro Morishima a , Toshiro Tomomatsu a , Kenji Okumura b, ⁎, Takahito Sone a , Hideyuki Tsuboi a , Yasuhiro Morita a , Yosuke Inoue a , Ruka Yoshida a , Yoshimitsu Yura c , Toyoaki Murohara c a Department of Cardiology, Ogaki Municipal Hospital, Ogaki, Japan b Department of Cardiology, Tohno Kosei Hospital, Mizunami, Japan c Department of Cardiology, Nagoya University Graduate School of Medicine, Nagoya, Japan article info Article history: Received 23 March 2015 Accepted 24 March 2015 Available online 27 March 2015 Keywords: Acute myocardial infarction Atrial fibrillation Cardiac mortality Pump failure Co-occurrence of atrial fibrillation (AF) with acute myocardial in- farction (AMI) has been documented with increasing frequency, and its adverse impact on mortality is consistent with the observations re- ported by a recent review [1]. However, it is unclear whether New- onset and preexisting AF portend different risks. We recently encoun- tered a patient with extensive AMI in whom hemodynamics were completely deteriorated by AF emergence despite mechanical supports and were fully recovered by sinus rhythm restoration by catheter abla- tion [2]. This case suggested the hypothesis that transition from the sinus rhythm to AF may be involved in the deterioration of heart failure leading to death in the short term following AMI onset. Accordingly, we estimated the impact of the two types of concomitant AF on the early trends in cardiac mortality The study population consisted of 732 consecutive AMI patients (age 69 ± 13 years old) seen at Ogaki Municipal Hospital. They were regis- tered at admission, and all of them underwent emergent coronary angi- ography and they were, except 5, revascularized with percutaneous coronary intervention (n = 725) or with coronary bypass surgery (n = 2). Patients were monitored by telemetry during the index hospi- talization. The study protocol complied with the Declaration of Helsinki and was approved by the local ethics committees of Ogaki Municipal Hospital. AF was defined as no discernible P waves and irregular RR intervals lasting at least 30 s. Patients were classified as having New-onset AF (n = 79. 10.8%) if they had no AF on admission, but had at least one ep- isode of AF recorded on electrocardiography or telemetry. Patients ob- served with AF on hospital admission were classified as the Pre-AF group (n = 34, 4.6%). Patients with no evidence of AF during hospitali- zation belonged to the Non-AF group (n = 619, 84.6%). Overall mortality in the 90 days after AMI onset was 32%, 21%, and 8% in the New-onset AF, Pre-AF, and Non-AF groups, respectively. The prevalence of cardiac death in either of the New-onset AF and Pre-AF groups was significantly greater than that in the Non-AF group (P b 0.001 and P b 0.05, respectively, by an extension of Fisher's exact test). In particular, the prevalence of pump-failure death was much higher in the New-onset AF group (20% vs. 12% and 5% for Pre-AF and Non-AF, respectively). The log-rank test revealed that the survival only in the New-onset AF group was significantly reduced when compared with that in the Non- AF group (Fig. 1). There was no statistical significance in mortality be- tween the New-onset AF and Pre-AF groups. In a multivariate backward stepwise logistic regression model retaining parameters significant at the 0.05 level, higher Killip class, reduced eGFR and LVEF, anterior wall AMI, and New-onset AF were significantly associated with increas- ing cardiac death and pump-failure death (Table 1). Although AMI introduces left ventricular dysfunction, the presence of AF prior to the onset appears to be associated with previously exag- gerated cardiovascular function compared with sinus rhythm and is often accompanied with the coexistence of chronic heart failure before AMI onset. AF may cause adverse hemodynamic effects, such as loss of atrial contraction, rapid ventricular rates, loss of atrioventricular syn- chrony, and an irregular RR interval, leading to a decrease in cardiac out- put [3,4]. So far, several studies have reported conflicting results regarding the prognostic differences between New-onset and preexisting AFs. International Journal of Cardiology 187 (2015) 475–477 ☆ All the authors take responsibility for all aspects of the reliability and freedom from bias of the data presented and their discussed interpretation. ☆☆ The present study was not supported by any grant or by any external source of funding or industry sponsorship. ⁎ Corresponding author at: Tohno Kosei Hospital, 76-1 Tokicho, Mizunami 509-6101, Japan. E-mail address: kenji@med.nagoya-u.ac.jp (K. Okumura). http://dx.doi.org/10.1016/j.ijcard.2015.03.379 0167-5273/© 2015 Elsevier Ireland Ltd. All rights reserved. Contents lists available at ScienceDirect International Journal of Cardiology journal homepage: www.elsevier.com/locate/ijcard