Assessing stroke risk in atrial fibrillation

Assessing stroke risk in Atrial fibrillation A/Prof Nguyen Quang Tuan., MD., PhD., FACC Hanoi Heart Hospital Prevalence of AF • AF is considered highly prevalent1–6 – ATRIA study – prevalence in US population estimated at ~1%:1 • Prevalence estimated for AF:1–10 – US: 3.3 million people – Europe: > million people – Asia-Pacific: incidence of AF is not known in many Asia-Pacific countries; prevalence ranges from 770 to 1,634 per 100,000 population – Latin America: incidence of AF is not known in many Latin American countries; in Brazil ~1.5 million people are thought to be living with AF Go AS et al JAMA 2001;285:2370–2375; Heeringa J et al Eur Heart J 2006;27:949–953; Frost L et al Int J Cardiol 2005;103:78–84; DeWilde S et al Heart 2006;92:1064–1070; Miyasaka Y et al Circulation 2006;114:119–125; Zhou Z and Hu D J Epidemiol 2008;18:209– 216; Fuster V et al Circulation 2006;114:700–752; Zimerman LI et al Arq Bras Cardiol 2009;92:1–39; ESC Guidelines Eur Heart J 2010; 31:2369-2429; 10.Naccarelli GV et al Am J Cardiol 2009;104(11):1534-9 Lifetime risk of developing AF • At ≥40 years of age, the remaining lifetime risk for developing AF is: – 26.0% for men – 23.0% for women • In the absence of previous chronic heart failure or MI, the lifetime risk of AF at age ≥40 years is reduced similarly for both men and women: – 16.3% for men – 15.6% for women Lloyd-Jones DM et al Circulation 2004;110:1042–1046 Proportion of strokes attributable to AF increases with age Framingham Heart Study (N=5,070) Attributable risk for AF (%) 25 23.5% 20 15 9.9% 10 2.8% 1.5% 50–59 60–69 70–79 Age (years) Significant increase in AF-attributable stroke risk with age (p-value for trend 7 days or requires cardioversion) Long-standing persistent (>1 year) Permanent (accepted) Different types of AF The arrhythmia tends to progress from paroxysmal (self-terminating, usually 5 minutes 54 patients 76 patients 42 patients patients AF >24 hour 59 patients 113 patients 45 patients patients CHADS2 ≥3 Botto GL et al J Cardiovasc Electrophysiol 2009;20:241–248 CHADS2 risk stratification for stroke prevention in patients with AF • Congestive heart failure +1 • Hypertension +1 • Age ≥75 years Risk category Score +1 • Diabetes mellitus +1 • Prior Stroke or TIA +2 Low Intermediate Moderate to high ≥2 • or points are assigned as shown for each of the risk factors above • Stroke risk – low, intermediate, high – is determined by the cumulative score Gage BF et al Circulation 2004;110:2287–2292; Fuster V et al Circulation 2006;114:e257–354; Singer DE et al Chest 2008;133:546S–592S CHADS2 score and stroke risk in patients with AF Item Diabetes mellitus Stroke/TIA 18.2 (10.5–27.4) 12.5 (8.2–17.5) 8.5 (6.3–11.1) 5.9 (4.6–7.3) 4.0 (3.1–5.1) Age ≥75 years Stroke rate (95% CI)* Hypertension CHADS2 Congestive heart failure Points 2.8 (2.0–3.8) 1.9 (1.2–3.0) 1 Add points together *Per 100 patient-years without antithrombotic therapy Gage BF et al JAMA 2001;285:2864–2287 CHADS2 limitations • Does not recognize all risk factors – Female gender – Vascular disease (MI, peripheral artery disease, aortic plaque) • Age >75 years is not a dichotomous risk factor – Risk increases from age 65 years onwards • A high proportion of patients are classified as intermediate risk – >60% in Euro Heart AF cohort – Uncertainty regarding the optimal form of thromboprophylaxis • Does not distinguish between subtypes of stroke • May require re-evaluation for use with the new OACs Lip GY et al Chest 2010;137:263–272; Karthikeyan G and Eikelboom JW Thromb Haemost 2010;104:45–48 CHA2DS2-VASc vs CHADS2 • CHADS2 is useful but has some limitations – Some risk factors are not recognized; stroke risk may be underestimated – Age is not a binary risk factor – High proportion of patients categorized at intermediate risk • CHA2DS2-VASc – More reliably identifies patient’s risk – Only small proportion categorized as intermediate risk – Simplifies (dichotomizes) selection of patients for anticoagulation – Removes uncertainty regarding the optimal form of thromboprophylaxis Olesen JB et al BMJ 2011;342:d124 CHA2DS2-VASc scheme Risk factor Points Congestive heart failure/left ventricular dysfunction* +1 Hypertension +1 Age ≥75 years +2 Diabetes mellitus +1 Previous stroke/TIA/thromboembolism +2 Vascular disease (MI, aortic plaque, peripheral artery disease)# +1 Age 65–74 years +1 Sex category (female) +1 Maximum score *Left ventricular ejection fraction 75 years • Hypertension • Mode/severe reduction in systolic function and/or heart failure • Diabetes mellitus • Previous stroke/TIA/systemic embolism or • ≥2 risk factors (from list opposite) NICE 2006 (refined by Lip et al 2010) Age 160 mm Hg) Abnormal renal or liver function Points 1+1 Stroke Bleeding Labile INRs Elderly (age >65 years) Drugs or alcohol Cumulative score Pisters R et al Chest 2010;138:1093–1100 1+1 Range 0−9 Higher bleeding rates seen with high HASBLED score (p-value for trend