International normalized ratio for the guidance of warfarin treatment in elderly patients after cardiac valve replacement

A post-hoc interpretable ensemble model to feature effect analysis in warfarin dose prediction for Chinese patients

To interprete the importance of clinical features and genotypes for warfarin daily dose prediction, we developed a post-hoc interpretable framework based on an ensemble predictive model. This framework includes permutation importance for global interpretation and local interpretable model-agnostic explanation (LIME) and shapley additive explanations (SHAP) for local explanation. The permutation importance globally ranks the importance of features on the whole data set. This can guide us to build a predictive model with less variables and the complexity of final predictive model can be reduced. LIME and SHAP together explain how the predictive model give the predicted dosage for specific samples. This help clinicians prescribe accurate doses to patients using more effective clinical variables. Results showed that both the permutation importance and SHAP demonstrated that VKORC1, age, serum creatinine (SCr), left atrium (LA) size, CYP2C9 and weight were the most important features on the whole data set. In specific samples, both SHAP and LIME discovered that in Chinese patients, wild-type VKORC1-AA, mutant-type CYP2C9*3, age over 60, abnormal LA size, SCr within the normal range, and using amiodarone definitely required dosage reduction, whereas mutant-type VKORC1-AG/GG, small age, SCr out of normal range, normal LA size, diabetes and heavy weight required dosage enhancement.

Mechanical valve replacement without anticoagulation: a case report

Background

For patients who undergo mechanical valve replacement, the greatest disadvantage is that they require long-term or permanent use of anticoagulant therapy to prevent thromboembolism. To date, mechanical valve replacement without anticoagulation has been published in the literature.

Case summary

We present the case of a 75-year-old female who underwent mechanical mitral valve replacement (MVR) on mid-June, 2007. However, this patient had not been taking anticoagulant medication since she experienced warfarin overdose in the first month after the operation. She had been well without using any anticoagulation, and there were no complications of the mechanical valve.

Discussion

There was no thrombosis for such a long period of time because she suffered from FX deficiency. To the best of our knowledge, she may be the only patient who has been well without any anticoagulation since not taking warfarin 12 years ago.

New warfarin anticoagulation management model after heart valve surgery: rationale and design of a prospective, multicentre, randomised trial to compare an internet-based warfarin anticoagulation management model with the traditional warfarin management model

INTRODUCTION

Warfarin is an effective anticoagulant and the only oral anticoagulant available for patients with mechanical heart valves. The prothrombin time and the associated international normalised ratio (INR) are routinely tested to monitor the response to anticoagulation therapy in patients. Patients who undergo mechanical heart valve replacement need lifelong anticoagulation therapy, and their INR is regularly measured to adjust the anticoagulation strength and the dose of anticoagulation drugs. Appropriate warfarin anticoagulation management can reduce patient complications, such as bleeding and thrombosis, and improve the long-term survival rate. We propose modern internet technology as a platform to build a warfarin anticoagulation follow-up system after valve replacement surgery. This system will provide doctors and patients with more standardised and safer follow-up methods as well as a method to further reduce the risk of warfarin anticoagulation-related complications and improve its therapeutic effects.

METHODS AND ANALYSIS

A prospective, multicentre, randomised, controlled trial will be conducted. A total of 700 patients who require long-term warfarin anticoagulation monitoring after heart valve replacement will be enrolled and randomly divided at a 1:1 ratio into a traditional outpatient anticoagulation management group and a group undergoing a new method of management based on the internet technology with follow-up for 1 year. Differences in the percentage of time in the therapeutic range (TTR), drug dose adjustments, bleeding/thrombosis and other related complications will be observed. The primary endpoint is the difference in the TTR between the two groups. The purpose of this study is to explore a safer and more effective mode of doctor-patient interaction and communication in the internet era. As of 13 July 2019, 534 patients had been enrolled.

ETHICS AND DISSEMINATION

This study protocol was approved by the Ethics Committee of Beijing Anzhen Hospital, Capital Medical University. The results will be published in a peer-reviewed medical journal.

TRIAL REGISTRATION NUMBER

ChiCTR1800016204.