269 Previously known and newly diagnosed atrial fibrillation complicating initial acute myocardial infarction: a community-wide perspective

Abstract

Atrial fibrillation (AF) is an understudied entity within myocardial infarction (MI) comorbidity. AF carries an increased risk of death but whether this risk is independent of other characteristics remains controversial. Our community-based data allow us, for the first time, to study the occurrence of AF over a long period of observation after MI and determine its impact on mortality post-MI. From an existing MI incident cohort (1983–2007), AF was identified by diagnostic codes for prior AF and from an ECG database for new-onset AF. Heart failure (HF) was defined by the Framingham criteria. Patients were followed from MI until death or last follow-up. Proportional hazards regression examined the association of AF with post-MI mortality. Among 3215 MI patients (mean age 68 y, 42% women), 303 patients (9%) had prior AF. During a mean follow-up of 7 y, 215 patients (30%) developed AF 2 days and 511 (70%) > 2 days of MI. 1639 deaths were observed and AF was associated with an increased risk of death (table). After adjusting for MI characteristics, AF is an independent predictor of long-term mortality, irrespective of its timing. This underscores the importance of its evaluation and management after MI. Impact of Atrial Fibrillation on long-term Mortality in Myocardial Infarction Patients Prior AF AF 2 days post-MI AF > 2 days post-MI HR (95% CI) p-value HR (95% CI) p-value HR (95% CI) p-value Unadjusted 3.54 (3.06,4.10) <0.0001 2.98 (2.51,3.53) <0.0001 4.29 (3.77,4.89) <0.0001 Adjusted for age, sex and comorbidity 1.68 (1.44,1.95) <0.0001 1.80 (1.51,2.14) <0.0001 2.86 (2.51,3.26) <0.0001 Adjusted for age, sex, comorbidity and HF 1.46 (1.26,1.70) <0.0001 1.60 (1.34,1.90) <0.0001 2.30 (2.01,2.63) <0.0001