Impact of atrial fibrillation type during acute coronary syndromes: Clinical features and prognosis

Atrial fibrillation (AF) is widely recognized as an adverse prognostic factor during acute myocardial infarction, although the impact of AF type – new-onset (nAF) or pre-existing (pAF) – is still controversial. To identify the clinical differences and prognosis of nAF and pAF during acute coronary syndromes (ACS). We performed a retrospective observational cohort study including 1373 consecutive patients (mean age 64 years, 77.3% male) admitted to a single center over a three-year period, with a six-month follow-up. AF rhythm was identified in 14.5% patients, of whom 71.4% presented nAF and 28.6% pAF. When AF types were compared, patients with nAF more frequently presented with ST-elevation ACS (p=0.003). Patients with pAF, in turn, were older (p=0.032), had greater left atrial diameter (p=0.001) and were less likely to have significant coronary lesions (p=0.034). Regarding therapeutic strategy, nAF patients were more often treated by rhythm control during hospital stay (p<0.001) and were less often anticoagulated at discharge (p=0.001). Compared with the population without AF, nAF was a predictor of death during hospital stay in univariate (p<0.001) and multivariate analysis (OR 2.67, p=0.047), but pAF was not. During follow-up, pAF was associated with higher mortality (p=0.014), while nAF patients presented only a trend towards worse prognosis. AF during the acute phase of ACS appears to have a negative prognostic impact only in patients with nAF and not in those with pAF. A fibrilhação auricular (FA) é um reconhecido fator de mau prognóstico no enfarte agudo do miocárdio, no entanto, o impacto do tipo de FA, de novo (FAn) ou pré-existente (FAp), é ainda controverso. Identificar as diferenças clínicas e o prognóstico da FAn e da FAp nas síndromes coronárias agudas (SCA). Estudo retrospetivo observacional de coorte, incluindo 1373 doentes consecutivos (idade média 64 anos, 77,3% homens) com SCA, admitidos num hospital, ao longo de três anos, com follow-up de seis meses. A FA foi identificada em 14,5% doentes, dos quais 71,4% tinham FAn e 28,6% FAp. Comparando os tipos de FA, verificou-se que os doentes com FAn apresentaram mais frequentemente SCA com elevação do segmento ST (p=0,003). Por sua vez, a FAp foi mais comum em doentes idosos (p=0,032), com diâmetro superior da aurícula esquerda (p=0,001) e ausência de doença coronária (p=0,034). Quanto à estratégia terapêutica, os doentes com FAn foram mais vezes submetidos a controlo de ritmo durante o internamento (p<0,001), mas menos hipocoagulados à alta (p=0,001). Quando comparada com a população sem FA, a FAn foi preditora de morte hospitalar na análise univariada (p<0,001) e multivariada (OR 2,67, p=0,047), enquanto a FAp não. Já no follow-up, a FAp associou-se a maior mortalidade (p=0,014), enquanto os doentes com FAn apresentaram apenas uma tendência para um pior prognóstico. O impacto prognóstico negativo da FA na fase aguda das SCA parece ocorrer apenas nos doentes que apresentam FAn e não naqueles com FAp.