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International Normalized Ratio Variability: A Measure of Anticoagulation Quality or a Powerful Mortality Predictor
1CASMU Arrhythmia Service, Montevideo, Uruguay; Department of Cardiology, British Hospital, Montevideo, Uruguay.
Summary
Predicting mortality in atrial fibrillation (AF) patients on warfarin is crucial. Combining the CHA2DS2VASc score with INR variability, particularly standard deviation of INR (SDINRs), offers superior prognostic value over CHA2DS2VASc alone.
Area of Science:
- Cardiology
- Pharmacology
- Clinical Medicine
Background:
- Atrial fibrillation (AF) significantly increases mortality risk.
- Risk stratification is essential for managing AF patients.
- Oral anticoagulants like warfarin are vital but require careful monitoring.
Purpose of the Study:
- To compare the prognostic value of the CHA2DS2VASc score versus INR variability in predicting mortality in AF patients on warfarin.
- To evaluate the combined predictive power of CHA2DS2VASc and INR variability.
Main Methods:
- Observational study of 589 AF patients on warfarin for over 1 year.
- Calculation of CHA2DS2VASc, HAS-BLED, and SAMe-TT2R2 scores.
- Assessment of INR variability using time-in-therapeutic-range (TTR), %INRs in range, and standard deviation of INRs (SDINRs).
Main Results:
- Mean TTR was 53%, mean %INRs in range was 50.2%, and mean SDINRs was 0.84.
- 11.5% of patients died during the study period, with heart failure, bleeding, and ischemic stroke as primary causes.
- Patient survival correlated with TTR, %INRs in range, SDINRs, left ventricular ejection fraction, CHA2DS2VASc, and the combination of CHA2DS2VASc + SDINRs.
Conclusions:
- INR variability is a valuable tool for assessing anticoagulation quality.
- Combining CHA2DS2VASc and INR variability (especially SDINRs) enhances mortality prediction in warfarin-treated AF patients.
- SDINRs is a strong predictor of mortality compared to other INR variability metrics.
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