International Normalized Ratio and Mortality Risk in Acute Heart Failure and Nonvalvular Atrial Fibrillation Patients Receiving Vitamin K Antagonists

Abstract

Introduction and objectives: Heart failure patients with nonvalvular atrial fibrillation (NVAF) on treatment with vitamin K antagonists (VKA) often have suboptimal international normalized ratio (INR) values. Our aim was to evaluate the association between INR values at admission due to acute heart failure and mortality risk during follow-up.

Methods: In this observational study, we retrospectively assessed INR on admission in 1137 consecutive patients with acute heart failure and NVAF who were receiving VKA treatment. INR was categorized into optimal values (INR = 2-3, n = 210), subtherapeutic (INR < 2, n = 660), and supratherapeutic (INR > 3, n = 267). Because INR did not meet the proportional hazards assumption for mortality, restricted mean survival time differences were used to evaluate the association among INR categories and the risk of all-cause mortality.

Results: During a median [interquartile range] follow-up of 2.15 years [0.71-4.29], 495 (43.5%) patients died. On multivariable analysis, both patients with subtherapeutic and supratherapeutic INR showed higher risks of all-cause mortality, as evidenced by their restricted mean survival time differences at 5 years' follow-up: -0.50; 95%CI, -0.77 to -0.23 years; P < .001; and -0.40; 95%CI, -0.70 to -0.11 years; P = .007, respectively, compared with INR 2-3.

Conclusions: In acute heart failure patients on treatment with VKA for NVAF, INR values out of normal range at admission were independently associated with a higher long-term mortality risk.

Keywords: Atrial fibrillation; Fibrilación auricular; Heart failure; Insuficiencia cardiaca; International normalized ratio; Razón internacional normalizada.