For managing patients with atrial fibrillation (AF), there are several good risk scores for stroke or thromboembolism and similar tools for predicting major bleeding risk. Given the overlap between stroke and bleeding risk factors in patients with AF, investigators have sought to develop a composite risk-stratification score for both stroke/thromboembolism and bleeding.

Investigators used patients enrolled in AMADEUS, a multicenter, randomized, open-label noninferiority study comparing fixed-dose idraparinux with conventional anticoagulation by dose-adjusted vitamin K antagonists (VKA). They used the nearly 2,300 patients in the VKA arm to identify independent predictors of stroke, non-central nervous system systemic embolism, major bleeding, systemic or venous embolism, MI, or cardiovascular death.

Based on this new analysis, 1 independent predictors included age, previous stroke/transient ischemic attack [TIA], aspirin use, time in therapeutic range, and LV systolic dysfunction.

The results led to the development of two novel composite risk-prediction scores that were then validated externally in a "real-world" cohort of 441 outpatients with AF receiving anticoagulation treatment. Both composite scores demonstrated numerically higher discriminatory performance and a positive net reclassification versus currently used risk models (CHADS2, CHA2DS2-VASc, and HAS-BLED).

However, these composite risk scores did not perform better than the easier and more practical "traditional" stroke and bleeding risk scores that are currently in use, which allow greater practicality and a more personalized balancing of risks.

Simplicity is Best

When originally presented at the 2013 ESC meeting, discussant Francisco Marín, MD, PhD, noted that "the strengths of the study by Professor Lip et al. are remarkable." He cited:

• This formal assessment of a composite risk score to assess overall clinical outcome in patients with AF takes into account the development of many oft-forgotten cardiovascular events, such as MI.
• The authors explored their hypothesis in a well-defined cohort of AF patients from AMADEUS.
• Lip et al. confirmed several variables as important risk factors for adverse events in AF, such as concomitant aspirin intake and the quality of oral anticoagulant (OAC) therapy (assessed by time in therapeutic range). The addition of aspirin to VKA did not offer more protection but increased the risk of bleeding. Thus, Dr. Marin said, we should check the quality of OAC control in our patients, and in the case of nonoptimal INR control, look for alternatives (e.g., novel OACs).
• Professor Lip’s conclusion was very sensible: Simplicity is best. Dr. Marin added, we need simple tools for assessing the risk of our patients for daily clinical decision making: use a stroke score (CHA₂DS₂-VASc) to assess stroke risk, and a bleeding score (HAS-BLED) to assess bleeding risk.

Speaking of aspirin, a number of guidelines that advocate OAC for stroke prevention in AF directly recommend against the use of aspirin in this setting, including those from the ESC, the Asia Pacific Heart Rhythm Society, and most recently the UK National Institute for Health and Care Excellence (NICE). In early 2014, Dr. Lip was first author of an ESC paper documenting that aspirin is still being used by too many patients with AF. "The perception that aspirin is a safe and effective drug for preventing strokes in AF needs to be dispelled," said Professor Lip. "If anything, you could say that giving aspirin to patients with AF is harmful because it is minimally or not effective at stroke prevention, yet the risk of major bleeding or intracranial hemorrhage is not significantly different to well-managed oral anticoagulation."

Reference

1. Lip GYH, Lane DA, Buller H, Apostolakis S. Chest. 2013;144:1839-47.

To listen to an interview with Gregory Y. H. Lip, MD, about assessing stroke risk in AF patients, visit youtube.cswnews.org. The interview was conducted by Alfred A. Bove, MD, PhD.

Keywords: Vitamin K, International Normalized Ratio, Oligosaccharides, Stroke, Intracranial Hemorrhages, Ischemic Attack, Transient, Decision Making, Atrial Fibrillation, Risk Factors, Embolism

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