How to Manage Occult Atrial Fibrillation Detected on Long-Term Monitoring

Stroke incidence and anticoagulation treatment in patients with pacemaker-detected silent atrial fibrillation

Background

Silent atrial fibrillation (AF) episodes are common but the role of anticoagulation treatment is under debate.

Methods

Consecutive patients with dual-chamber pacemakers for sinus node disease or AV block/bundle branch block were retrospectively enrolled and the development of silent AF, any anticoagulation and the incidence of ischaemic stroke and dementia were recorded.

Results

In total 411 patients without and 267 with known AF at implant were included. During a median follow-up of 38 months, 30% (125/411) of patients without known AF at implant were diagnosed with silent AF, 62% of those had or were prescribed anticoagulation. Heart failure (p = 0.03) and age >75 years (p = 0.0002) were risk markers for incident silent AF. In patients with known AF at implant, 80% (216/267) were on anticoagulation at implant. The annual stroke incidence was 2.1% in patients with known AF at implant, as compared to 1.9% in patients who developed silent AF during follow-up, and 1.4% in patients without AF. Vascular dementia developed in 11.2% and 6.2% respectively in patients with known AF versus no AF (p = 0.048) as well as in 5.6% of those with silent AF (p = 0.09)

Conclusion

The stroke risk in our study population with an incident silent AF diagnosis may have been significantly decreased by the high proportion of anticoagulation treatment. This could imply that without this treatment the stroke risk might have been high enough to justify anticoagulation. Development of vascular dementia was twice as common among patients with known AF as compared to those witht silent AF or no AF. More data is needed to inform the optimal treatment for these patients.

Management of Complications in Anticoagulated Patients with Atrial Fibrillation

Oral anticoagulation is mandatory for patients at high risk of thromboembolism, but the risk of bleeding should also be taken into account. Direct oral anticoagulants are now recommended for non-valvular AF as a potential alternative to warfarin. In this article we discuss methods to assess the anticoagulant effect of these agents, specific and general antidotes, and management of complications such as embolic and haemorrhagic stroke, and significant bleeding.

Clinical Prediction Model for Time in Therapeutic Range While on Warfarin in Newly Diagnosed Atrial Fibrillation

BACKGROUND

Though warfarin has historically been the primary oral anticoagulant for stroke prevention in newly diagnosed atrial fibrillation (AF), several new direct oral anticoagulants may be preferred when anticoagulation control with warfarin is expected to be poor. This study developed a prediction model for time in therapeutic range (TTR) among newly diagnosed AF patients on newly initiated warfarin as a tool to assist decision making between warfarin and direct oral anticoagulants.

METHODS AND RESULTS

This electronic medical record-based, retrospective study included newly diagnosed, nonvalvular AF patients with no recent warfarin exposure receiving primary care services through a large healthcare system in rural Pennsylvania. TTR was estimated as the percentage of time international normalized ratio measurements were between 2.0 and 3.0 during the first year following warfarin initiation. Candidate predictors of TTR were chosen from data elements collected during usual clinical care. A TTR prediction model was developed and temporally validated and its predictive performance was compared with the SAMe-TT2R2 score (sex, age, medical history, treatment, tobacco, race) using R2 and c-statistics. A total of 7877 newly diagnosed AF patients met study inclusion criteria. Median (interquartile range) TTR within the first year of starting warfarin was 51% (32, 67). Of 85 candidate predictors evaluated, 15 were included in the final validated model with an R2 of 15.4%. The proposed model showed better predictive performance than the SAMe-TT2R2 score (R2=3.0%).

CONCLUSIONS

The proposed prediction model may assist decision making on the proper mode of oral anticoagulant among newly diagnosed AF patients. However, predicting TTR on warfarin remains challenging.

Stroke Prevention for Patients with Atrial Fibrillation: Beyond the Guidelines

Atrial fibrillation (AF) is the most common serious heart rhythm disorder, with a lifetime incidence of 1 in 4 for patients >40 years of age[1]. AF is a major cause of death and disability, as it is associated with a 4-5 fold increase in the risk of ischemic stroke[2]. In patients with AF, oral anticoagulation (OAC) therapy can reduce the risk of stroke by about two-thirds and the risk of all-cause mortality by approximately one-quarter, but is associated with an increased risk of bleeding[3], [4]. Atrial fibrillation (AF) is the most common serious heart rhythm disorder and is associated with an increased risk of ischemic stroke. This risk can be moderated with oral anticoagulation therapy, but the decision to do so must be balanced against the risks of bleeding. Herein, we discuss three emerging areas where more high-quality evidence is required to guide risk stratification: 1) the relationships between the pattern and burden of AF and stroke 2) the risk conferred by short episodes of device-detected "sub-clinical" atrial fibrillation (SCAF) and 3) the significance of AF that occurs transiently with stress (AFOTS), as is often detected during medical illness or after surgery. Risk stratification is important to identify patients with AF who can benefit from OAC therapy. There are, however, several common clinical scenarios where guidelines do not yet provide direction for stroke prevention; or do so based on limited high-quality evidence.

Clinical Stroke prevention in atrial fibrillation

Oral anticoagulation therapy has reduced the risk of ischaemic stroke and improved the outcomes for patients with atrial fibrillation considerably. The emergence of the non-vitamin K oral anticoagulants as alternatives to vitamin K antagonists has significantly changed the practice of stroke prevention in atrial fibrillation. As the main complication with antithrombotic therapy is bleeding, physicians should always balance the risk of ischaemic stroke against intracranial haemorrhage and intervene where appropriate to reduce both risks. Individual approach is often mandatory due to heterogeneity of the risks and patient preferences. The purpose of this review is to summarise the current knowledge of the oral anticoagulation therapy in atrial fibrillation patients and guide physicians with the management of anticoagulants based on data from clinical trials and systematic reviews.