Newly Diagnosed Atrial Fibrillation in Acute Myocardial Infarction

Abstract

Background It remains controversial whether long-term clinical impact of newly diagnosed atrial fibrillation (AF) in the acute phase of acute myocardial infarction (AMI) is different from that of prior AF diagnosed before the onset of AMI. Methods and Results The current study population from the CREDO-Kyoto AMI (Coronary Revascularization Demonstrating Outcome Study in Kyoto Acute Myocardial Infarction) Registry Wave-2 consisted of 6228 patients with AMI who underwent percutaneous coronary intervention. The baseline characteristics and long-term clinical outcomes were compared according to AF status (newly diagnosed AF: N=489 [7.9%], prior AF: N=589 [9.5%], and no AF: N=5150 [82.7%]). Median follow-up duration was 5.5 years. Patients with newly diagnosed AF and prior AF had similar baseline characteristics with higher risk profile than those with no AF including older age and more comorbidities. The cumulative 5-year incidence of all-cause death was higher in newly diagnosed AF and prior AF than no AF (38.8%, 40.7%, and 18.7%, P<0.001). The adjusted hazard ratios (HRs) for mortality of newly diagnosed AF and prior AF relative to no AF remained significant with similar magnitude (HR, 1.31; 95% CI, 1.12-1.54; P<0.001, and HR, 1.32; 95% CI, 1.14-1.52; P<0.001, respectively). The cumulative 5-year incidence of stroke decreased in the order of newly diagnosed AF, prior AF and no AF (15.5%, 12.9%, and 6.3%, respectively, P<0.001). The higher adjusted HRs of both newly diagnosed AF and prior AF relative to no AF were significant for stroke, with a greater risk of newly diagnosed AF than that of prior AF (HR, 2.05; 95% CI, 1.56-2.69; P<0.001, and HR, 1.33; 95% CI, 1.00-1.78; P=0.048, respectively). The higher stroke risk of newly diagnosed AF compared with prior AF was largely driven by the greater risk within 30 days. The higher adjusted HRs of newly diagnosed AF and prior AF relative to no AF were significant for heart failure hospitalization (HR, 1.73; 95% CI, 1.35-2.22; P<0.001, and HR, 2.23; 95% CI, 1.82-2.74; P<0.001, respectively) and major bleeding (HR, 1.46; 95% CI, 1.23-1.73; P<0.001, and HR, 1.36; 95% CI, 1.15-1.60; P<0.001, respectively). Conclusions Newly diagnosed AF in AMI had risks for mortality, heart failure hospitalization, and major bleeding higher than no AF, and comparable to prior AF. The risk of newly diagnosed AF for stroke might be higher than that of prior AF.

Keywords: acute myocardial infarction; anticoagulation; atrial fibrillation; percutaneous coronary intervention; stroke.

Figure 1. Study flow chart.

AF indicates atrial fibrillation; AMI, acute myocardial infarction; CABG, coronary artery bypass grafting; CREDO‐Kyoto AMI Registry Wave‐2, Coronary Revascularization Demonstrating Outcome study in Kyoto AMI Registry Wave‐2; and PCI, percutaneous coronary intervention.

Figure 2. Kaplan‐Meier event curves for all‐cause death.

A, During the entire follow‐up period, and (B) Landmark analysis at 30‐day. Crude HRs and 95% CIs were indicated with reference to no AF. AF indicates atrial fibrillation; and HR, hazard ratio.

Figure 3. Kaplan‐Meier event curves for cardiovascular death, hospitalization for heart failure, myocardial infarction, and any coronary revascularization.

A, Cardiovascular death, (B) Hospitalization for heart failure, (C) Myocardial infarction, and (D) Any coronary revascularization. Crude HRs and 95% CIs were indicated with reference to no AF. AF indicates atrial fibrillation; and HR, hazard ratio.

Figure 4. Kaplan‐Meier event curves for stroke and major bleeding.

A, Stroke during the entire follow‐up period, (B) Landmark analysis at 30‐day for stroke, (C) Major bleeding during the entire follow‐up period, and (D) Landmark analysis at 30‐day for major bleeding. Crude HRs and 95% CIs were indicated with reference to no AF. AF indicates atrial fibrillation; and HR, hazard ratio.