Anticoagulation Therapy in Atrial Fibrillation in Combination With Acute Myocardial Infarction Influences Long-Term Outcome

Abstract

for the RIKS-HIA Registry Background-The American and European guidelines do not agree with regard to antithrombotic treatment in patients with atrial fibrillation (AF) and acute myocardial infarction (AMI), thus causing uncertainty among physicians. We investigated the prescription of oral anticoagulation (OAC) in patients discharged alive with AF after an AMI and the influence of OAC treatment on 1-year mortality. Methods and Results-This was a prospective cohort study using data from the Register of Information and Knowledge about Swedish Heart Intensive care Admissions (RIKS-HIA) on patients admitted to the coronary care units of 72 Swedish hospitals from 1995 to 2002. A total of 6182 patients discharged alive with first registry-recorded AMI and AF on discharge ECG were included. One-year mortality data were obtained from the Swedish National Cause of Death Register. Only 30% (nϭ1848) of the 6182 patients with AF were prescribed OAC. At 1 year, the unadjusted mortality was 31% (1183 deaths) in the platelet-inhibitors only group and 22% (414 deaths) in the OAC-treated group. In Cox regression analysis with adjustment for confounding factors, OAC treatment was associated with a reduction in 1-year mortality (relative risk 0.73; 95% CI 0.62 to 0.86; PϽ0.001) in hospital survivors of AMI with AF. The reduction in mortality appeared to be caused primarily by a lower rate of ischemic heart death (55.6% versus 62.0%) and fatal stroke (5.7% versus 7.5%) in the OAC group. This reduction of mortality was similar among most subgroups based on age, sex, baseline characteristics, previous disease manifestations, and medications. Conclusions-In daily clinical practice, OAC was only given to a minority (30%) of AMI patients with AF, despite the fact that OAC was associated with a 29% relative and 7% absolute reduction in 1-year mortality after adjustment for confounding variables. The results emphasize the importance of OAC treatment for AF after AMI. (Circulation. 2005; 112:3225-3231.)

Combined anticoagulation and antiplatelet therapy for high-risk patients with atrial fibrillation: a systematic review

“…Of these, 14 studies [50][51][52][53][54][55][56][57][58][59][60][61][62][63] (in 14 articles) reported data from observational designs, both prospective [50][51][52][53][54][55] and retrospective [56][57][58][59][60][61][62][63] in nature. The remaining four studies in 10 articles [64][65][66][67][68][69][70][71][72][73] were originally designed to assess the effectiveness of an anticoagulant without additional APT.…”

“…Retrospective outcomes (n = 8) [56][57][58][59][60][61][62][63] Prospective outcomes (n = 6) [50][51][52][53][54][55] Of the studies reporting non-randomised comparisons, six were retrospective, [56][57][58][60][61][62][63] and the time of APT use varied between the studies. The majority of these studies consisted of a retrospective review of medical records where prior knowledge of allocation of therapy was not possible.…”

“…The majority of these studies consisted of a retrospective review of medical records where prior knowledge of allocation of therapy was not possible. [50][51][52][53][56][57][58][59][60][61]63 However, all but five studies 50,55,59,62,73 clearly reported the criteria by which APT was used in the study. Of note is the study by Ezekowitz et al 73 [PETRO (Dabigatran with or without concomitant aspirin compared with warfarin alone in patients with non-valvular atrial fibrillation)], in which it was difficult to identify if APT was used at random or indicated in a subgroup.…”

“…The differences in the event rates reported by the included studies may reflect differences in the population risk profile, with some studies including high-risk AF populations (three RCTS 39,41,43 and seven nonrandomised comparisons 50,55,58,64,65,72,73 ) and/or intermediate-risk patients with AF (one RCT 39 ), whereas other studies did not report the risk profile of included patients (two RCTs 40,42 ) and 11 other nonrandomised comparisons. [51][52][53][54]56,57,[59][60][61][62][63] The sample size also varied considerably between included studies, from 43 participants in one RCT 40 to 118,606 in a large non-randomised comparison.…”

“…Studies compared a VKA, either warfarin, 40 41 In addition, the APT also varied (aspirin, triflusal, clopidogrel, and aspirin plus clopidogrel). In the studies reporting randomised comparisons, aspirin was utilised in different doses (300 mg, 42 325 mg 43 and 100 mg 41 ), and also in non-randomised comparisons (≤ 100 mg, 64,65,72 100 mg, 61 81 or 325 mg 73 and dose not specified in others 51,53,[56][57][58]62 ). Similarly, other antiplatelets were used in different doses such as triflusal (600 mg, 39 600 mg and 300 mg 54 ), clopidogrel (75 mg: 40 dose not specified 63 ) and dual APT of aspirin plus clopidogrel (dose not specified 50,63 ), which makes direct comparison between studies difficult.…”