Prevention of thromboembolism in patients with mitral stenosis and associated atrial fibrillation: effectiveness of low intensity (INR target 2) oral anticoagulant treatment

Risk of stroke or systemic embolism in patients with degenerative mitral stenosis with or without atrial fibrillation: A cohort study

Background

Atrial fibrillation (AF) is associated with an increased risk of stroke and the combination of AF and mitral stenosis (MS) is associated with a higher risk. In developed nations, degenerative mitral stenosis (DMS) constitutes a sizeable proportion of patients with MS. Current international guidelines do not offer recommendations regarding anticoagulation in these patients. The objective of this study was to describe the incidence of stroke or systemic embolism in patients with DMS with or without prevalent AF.

Methods

A cohort study of DMS patients from 1997 to 2018, using data from the Danish health registries. The cohort was stratified based on AF prevalence and prior ischemic stroke. The primary outcome was a diagnosis of ischemic stroke or systemic embolism after 1 year of follow-up from time of DMS diagnosis.

Results

The study included 1162 patients with DMS, of which 421 had prevalent AF. The incidence rate of stroke or systemic embolism after 1 year of follow-up was highest in the DMS without AF group (7.58 vs. 6.63 per 100 person-years). In both groups, DMS without AF and DMS with AF, the incidence rate was highest in patients with prior thromboembolic events (29.61 vs. 5.15 and 19.53 vs. 5.15, respectively).

Conclusions

The incidence rate of stroke or systemic embolism was highest in DMS patients without AF. Current Danish guidelines recommend DMS patients should be treated with anticoagulation only with concurrent AF, yet our results call for additional research to establish if DMS patients without AF could benefit from stroke prevention therapy.

Incidence of Acute Cerebrovascular Events in Patients with Rheumatic or Calcific Mitral Stenosis: A Systematic Review and Meta-analysis

BACKGROUND

Patients with mitral stenosis (MS) may be predisposed to acute cerebrovascular events (ACE) and peripheral thromboembolic events (TEE). Concomitant atrial fibrillation (AF), mitral annular calcification (MAC) and rheumatic heart disease (RHD) are independent risk factors. Our aim was to evaluate the incidence of ACEs in MS patients and the implications of AF, MAC, and RHD on thromboembolic risks.

METHODS

This systematic review was registered on PROSPERO (CRD42021291316). Six databases were searched from inception to 19th December 2021. The clinical outcomes were composite ACE, ischaemic stroke/transient ischaemic attack (TIA), and peripheral TEE.

RESULTS

We included 16 and 9 papers, respectively, in our qualitative and quantitative analyses. The MS cohort with AF had the highest incidence of composite ACE (31.55%; 95%CI 3.60-85.03; I²=99%), followed by the MAC (14.85%; 95%CI 7.21-28.11; I²=98%), overall MS (8.30%; 95%CI 3.45-18.63; I²=96%) and rheumatic MS population (4.92%; 95%CI 3.53-6.83; I²=38%). Stroke/TIA were reported in 29.62% of the concomitant AF subgroup (95%CI 2.91-85.51; I²=99%) and in 7.11% of the overall MS patients (95%CI 1.91-23.16; I²=97%). However, the heterogeneity of the pooled incidence of clinical outcomes in all groups, except the rheumatic MS group, were substantial and significant. The logit-transformed proportion of composite ACE increased by 0.0141 (95% CI 0.0111-0.0171; p<0.01) per year of follow-up.

CONCLUSION

In the MS population, MAC and concomitant AF are risk factors for the development of ACE. The scarcity of data in our systematic review reflects the need for further studies to explore thromboembolic risks in all MS subtypes.

Risk of Stroke With Mitral Stenosis: The Underlying Mechanism, Treatment, and Prevention

Mitral stenosis (MS), a valvular heart disease, is defined by the narrowing of the mitral valve orifice. The common risk factors for stroke include mitral annular calcification (MAC), diabetes mellitus (DM), male gender, hypertension (HTN), hyperlipidemia, and obesity. Endothelial damage, hypercoagulability, and blood stasis in the left atrium promote the development of the thrombus. Among all the risk factors described, MAC is the independent predictor of stroke. The complicated mechanisms responsible for thromboembolism, predisposing factors for thromboembolism, the risk of cerebrovascular accident (CVA) in MS patients, advanced standardized assessment models for identifying those at risk for stroke, and the possible advantages and disadvantages of available therapies have all been discussed in this review article. We have also discussed newer oral anticoagulants (NOACs) like dabigatran, edoxaban, apixaban, and rivaroxaban. Non-pharmacological therapies are also highlighted such as left atrial appendage ligation and occlusion devices. We also conducted a thorough review of the literature on the efficacy and safety of various NOACs in reducing the risk of stroke.

Effect of setting, monitoring intensity and patient experience on anticoagulation control: a systematic review and meta-analysis of the literature

OBJECTIVES

To investigate the relationship between time spent in the recommended target International Normalised Ratio (INR) range and the setting and intensity of anti coagulant monitoring, in both treatment-experienced and treatment-naive atrial fibrillation (AF) patients receiving oral anticoagulation (OAC) therapy for the prevention of ischaemic stroke.

RESEARCH DESIGN AND METHODS

Systematic review of published studies on participants with atrial fibrillation on anticoagulation therapy. We compared frequent monitoring (well-controlled, according to a strict protocol) versus infrequent monitoring (frequency representative of routine clinical practice), specialised care versus usual care, and naive versus prior anticoagulant use. Meta-analysis was performed using a random effects model.

RESULTS

36 studies were included, 22 (primary data) of AF patients managed in line with the consensus guidelines target INR range of 2.0-3.0, and 14 studies (secondary data) of mixed patient groups, including AF, with an INR target of 2.0-3.5. Both data sets were combined for sensitivity analysis. Pooled mean time in INR range was 59.1% (95% CI: 55.5, 62.8%) and 64.3% (95% CI: 60.5, 68.0%) for infrequent monitoring and frequent monitoring, respectively. Significantly more time was spent in range in specialist care settings compared to usual care: +11.3% (95% CI: 0.1-21.7%). Naive OAC users spent less time in range 56.5% (95% CI: 45.5-67.5%) than existing users 61.2% (95% CI: 57.2-65.2%). All of these differences were found to be significant in the sensitivity analyses.

CONCLUSIONS

INR control is variable and dependent on monitoring intensity and duration of anticoagulant therapy.

Effect of antithrombotic therapy in patients with mitral stenosis and atrial fibrillation: a sub-analysis of NASPEAF randomized trial

AIMS

The randomized NASPEAF study included non-valvular with prior embolism and mitral stenosis patients in the same group. This is a sub-study to specially focus on the antithrombotic therapy in mitral stenosis.

METHODS AND RESULTS

We analysed 311 patients with mitral stenosis, compared with 175 non-valvular atrial fibrillation patients with prior embolism, stratified by a history of previous embolism and assigned to anticoagulant therapy [target international normalized ratio (INR) = 2.0-3.0] or combined antiplatelet plus moderate intensity anticoagulant therapy. Median follow-up was 2.9 years. Outcomes were fatal and non-fatal embolism, stroke and myocardial infarction, sudden death, and death from bleeding. Combined therapy in mitral stenosis patients, compared with anticoagulant alone therapy, reduced the risk of vascular events by 58.3%. During equal therapy, the outcome annual rates were essentially the same in non-valvular and valvular patients [hazard ratio 0.90 (95% confidence interval 0.37-2.16), P = 0.81]. During anticoagulant alone therapy, the annual event rate in mitral stenosis patients without prior embolism was low (2.5%) and it was very high in patients with prior embolism (6.6%).

CONCLUSION

Combined therapy was effective in mitral stenosis patients. Prior embolism patients are not efficiently protected with anticoagulant alone therapy for an INR of 2.0-3.0.

Low-intensity anticoagulation for stroke prevention in elderly patients with atrial fibrillation: efficacy and safety in actual clinical practice

Low-intensity warfarin (INR 1.5 to 2.5) was started in 63 patients with atrial fibrillation (AF) and they were prospectively followed for 2.3 +/- 1.4 years to determine the efficacy and safety of anticoagulation for stroke prevention in actual clinical practice. Although the patients in this practice were older (76 +/- 7 years), consisted of more women (52%), and had more risk factors for stroke compared with those in clinical trials, the annual event rates of stroke and systemic embolism in this practice were comparable to those of patients receiving warfarin in clinical trials (2.0% vs. 1.4% and 0.7% vs. 0.3%). The rate of major bleeding did not significantly differ between this practice and clinical trials (0.7% vs. 1.3%). The rate of minor bleeding was significantly lower in this practice than in clinical trials (3.4% vs. 7.9%). The data suggest that low-intensity anticoagulation is effective and safe for stroke prevention in elderly patients with AF at stroke risk in actual clinical practice.

Molecular aspects of thrombosis and antithrombotic drugs

There have been major advances in our understanding of thrombosis and antithrombotic drugs. This review focuses on the molecular aspects of thrombus formation and antithrombotic therapy. Molecules involved in arterial thrombosis are derived from inflammatory cells in the atherosclerotic plaque and blood platelets. These molecules work in concert to promote plaque instability and thrombogenicity. Thrombus formation on the ruptured plaque is mediated by platelet and coagulation activation. By contrast, molecules involved in venous thrombosis are derived from the activated coagulation cascade. Platelets appear to play a secondary role. The antithrombotic drugs are classified according to their targeted constituents: antiplatelet agents and anticoagulants; the latter are further divided into non-specific anticoagulants, such as vitamin K antagonists and heparin, and direct thrombin inhibitors, including hirudin and argatroban. Currently available antiplatelet agents target glycoprotein IIbIIIa (abciximab, tirofiban, eptifibatide), cyclooxygenase-1 (aspirin) or adenosine diphosphate receptor, P2Y12 (clopidogrel).

The lowest effective intensity of prophylactic anticoagulation for patients with atrial fibrillation

BACKGROUND

Stroke prevention trials in patients with atrial fibrillation (AF) mainly studied the use of warfarin in Caucasians, and the international normalized ratio (INR) was targeted in the range of 2-4. The result may not necessarily be applicable to other ethnic groups. This study aimed to determine the optimal intensity of anticoagulation for stroke prevention in Chinese patients.

METHODS

We performed a retrospective study on all Chinese patients with AF taking warfarin for stroke prevention in our hospital from January 1, 2000, to June 30, 2002. Patients with a mechanical heart valve were excluded. We systematically studied their indication of using warfarin, duration of therapy and all INR results. Only those patients whose indications of using warfarin were consistent with the ACC/AHA/ESC Executive Summary were included. Thrombo-embolic episodes, sudden death, major bleeding, intracranial haemorrhage and the INR at the time of the event were recorded. The INR range was divided into six categories: <1.5, 1.5-1.9, 2.0-2.5, 2.6-3.0, 3.1-3.5, >3.5. The number of events was recorded for each category, and this formed the numerator. The denominator was the summation of time each patient stayed in each category of INR. The event rate was then calculated for each INR category.

RESULTS

555 patients were included in the analysis, they constituted 893 patient-years. The INR was kept below 2.6 in 84.9% of the time and between 1.5 and 1.9 in 35% of the time. The overall event rate in our patients was 6.0%, of which 3.9% were due to thrombo-embolic events and 2.1% were due to serious bleeding. The overall event rate was lowest in the INR range from 1.5 to 1.9. which is not significantly different from that of INR 2.0-2.5 and 2.6-3.0. The overall event rate was 3.6% in INR 1.5-3.0 which was significantly lower than 15.1% in INR <1.5 and 20.5% in INR >3.0 (p < 0.01).

CONCLUSIONS

Our retrospective cohort showed that a lower INR range of 1.5-3.0 was safe and effective for stroke prevention in Chinese patients treated in a single hospital.