For risk assessment and consequent anticoagulant use in atrial fibrillation(AF), biomarker-based ABC (Age, Biomarkers, Clinical History) scoring system has outperformed the conventional CHADS-VASc and HAS-BLED scores in recent trials where it was validated in patients already on anticoagulation therapy. To expand the universal utility of this novel scoring system, Benz et al have now evaluated its use in improving risk stratification in AF patients who are not candidates for anticoagulation therapy by conventional scoring systems. In their study published in Circulation, it was found that ABC-AF scores showed better discrimination than traditional risk scores and were recalibrated for precise risk estimation in these patients.
The main purpose of this study was to evaluate discrimination, calibration, and prognostic utility of the ABC-AF-stroke, ABC-AF-bleeding, and ABC-AF-death scores in patients with AF not receiving oral anticoagulation. In addition, the ABC-AF scores were compared with the currently guideline-recommended and widely used CHA2DS2-VASc and HAS-BLED scores.
They evaluated the ABC-AF scores in patients randomized to receive antiplatelet therapy, but not oral anticoagulation, in the ACTIVE A and AVERROES trials.
The ABC-AF-stroke score yielded a c-index of 0.70 in both cohorts. The ABC-AF-bleeding score had a c-index of 0.76 in the aspirin only cohort and 0.73 overall. Both scores were superior to risk scores recommended by current guidelines. The ABC-AF-death score yielded a c-index of 0.78 overall.
In order to predict absolute event rates in the absence of oral anticoagulation and to provide optimal clinical utility, the ABC-AF-stroke and ABC-AF-bleeding scores were successfully recalibrated. The ABC-AF scores can now, for the first time, provide decision support based on more precise estimates of expected event rates, with and without oral anticoagulation, in an individual patient with AF.
Both North American and European guidelines for the management of AF recommend the CHA2DS2-VASc score to guide initiation of long-term oral anticoagulant therapy. However, this score has shown only modest discrimination in both the derivation and several validation studies.
Since the original presentation of the CHA2DS2-VASc and HAS-BLED scores, the incremental prognostic value of the cardiac biomarkers NT-proBNP and cTnT for the risk of stroke and the oxidative stress and aging marker GDF-15 for the risk of bleeding and all three for the risk of death have been demonstrated in three very large studies of more than 30,000 well-characterized patients enrolled and randomized to different oral anticoagulant regimens in the RE-LY, ARISTOTLE and ENGAGE AF-TIMI 48 trials.
The superiority of the biomarker-based ABC-AF scores stems from their consistent use of continuous variables without arbitrary cut-off values, and biomarkers potently reflecting pathophysiological processes related to myocardial dysfunction, thrombogenicity, inflammatory activity and biological aging.
"The present study validates the ABC-AF-stroke, ABC-AF-bleeding and ABC-AF-death scores for risk estimation in two large cohorts of patients with AF not receiving oral anticoagulation. The ABC-AF scores can now provide improved decision support regarding treatment of an individual patient with AF", concluded the authors.
Source: Circulation journal: https://www.ahajournals.org/doi/abs/10.1161/CIRCULATIONAHA.120.053100?af=R