International Normalized Ratio Elevation as a Marker for Clinical Change in Mechanical Circulatory Support Patients

Abstract

Purpose To determine if an unexpectedly elevated international normalized ratio (INR) may be associated with symptomatic clinical change in mechanical circulatory support (MCS) patients on relatively stable doses of warfarin. We hypothesize that a significant INR rise while on consistent doses of warfarin may be a signal for current or pending declines in clinical status. Methods A retrospective review of 64 outpatient MCS recipients was performed during the period 9/2013-5/2018. Patient information regarding signs and symptoms of acute decompensation were collected. These included hospital admission for fluid overload, low-flow alarms with syncope, ventricular tachyarrhythmia with/without implantable cardiac defibrillator firing, right ventricular failure, or noted fluid overload at clinic visits necessitating diuretic increase. An INR rise to values >4.0 was compared to a concurrent incidence of changes in clinical status or need for intervention within the subsequent month after an unexplained labile INR. Results The cohort included both left ventricular assist device and total artificial heart patients. Sixty-two INR values >4.0 occurred at hospital admission or preceded a clinical event by 30 days or less. The average INR that fit these criteria was 5.0 +/- 1.3. The positive predictive value of an acute clinical change as a potential for INR elevation was 28.7% with a sensitivity of 0.54. Fifty-three instances of a herein defined decline in clinical status were not associated with elevated INR. The negative predictive value of an INR 4.0, nor in the 5,836 recorded INRs that were Conclusion An unexpected INR rise may be evidence of a worsening scenario for an MCS patient experiencing a change in clinical status.