Atrial Fibrillation Significantly Increases Total Mortality and Stroke Risk Beyond that Conveyed by the CHADS2 Risk Factors

BACKGROUND: Atrial fibrillation (AF) is associated with an increased risk of mortality and stroke. However, it is unclear if AF is independently associated with these poor outcomes or it is merely a risk marker of other processes that convey the risk. METHODS: Consecutive patients who underwent angiography for suspicion of coronary artery disease, but without a history of AF, were studied. Traditional CHADS2 (congestive heart failure, hypertension, age >75 years, diabetes, stroke/transient ischemic attack) risk factors for each patient were recorded. RESULTS: A total of 343 AF patients (age = 69 +/- 10 years, 215 63% male) and 2,945 non-AF patients (age = 63 +/- 12 years, 2,012 67% male) were studied. Among AF patients, 51 (15%) had a myocardial infarction (MI), 35 (10%) had a stroke, and 180 (52%) died. CHADS2 score incrementally increased risk of stroke (adjusted hazard ratio HR for 1:1.92, 2:2.30, 3:1.14, 4:3.83, 5:10.96; P-trend = 0.14), death (HR for 1:1.83, 2:2.34, 3:3.69, 4:2.27, 5:4.53; P-trend < 0.001), and major adverse cardiac event (MACE)(HR for 1:1.29, 2:1.54, 3:2.07, 4:2.41, 5:2.68; P-trend = 0.002). Among non-AF patients, CHADS2 score incrementally increased risk of stroke (HR for 1:1.18, 2:3.17, 3:5.08, 4:10.78, 5:7.50; P-trend < 0.001), MI (HR for 1:1.05, 2:1.46, 3:1.57, 4:0.53, 5:4.76; P-trend = 0.002), death (HR for 1:1.79, 2:3.22, 3:6.23, 4:9.09, 5:14.00; P-trend < 0.001), and MACE (HR for 1:1.47, 2:2.36, 3:4.16, 4:5.91, 5:7.56; P-trend < 0.001). Among all patients, both CHADS2 score (all P < or = 0.001) and AF were independent risk factors for stroke (AF: P = 0.002), MI (AF: P = 0.035), death (AF: P < 0.001), and MACE (AF: P < 0.001). CONCLUSION: The CHADS2 score is a powerful predictor of stroke and death. AF increases the risk of these outcomes in an independent manner. These data support the concept that AF is a risk factor of future cardiovascular disease.