Rivaroxaban vs. Warfarin in CVT Treatment

Background:

Cerebral venous and/or dural sinus thrombosis (CVT) is an uncommon but increasingly recognized form of stroke accounts for up to 1% of all cerebral vascular accidents (CVAs), with an estimated incidence of 5 cases per million people per year, it usually affects young patients with a female to male ratio of 3:1.

The pathogenesis of CVT is still not entirely clear. Partly because of the highly variable venous anatomy and the shortage of animal studies. However, decreased venous blood flow drainage and cerebrospinal fluid (CSF) absorption may lead to elevation of intracranial pressure and/or cerebral parenchymal lesions or dysfunction that may contribute to the clinical features of CVT.

Diagnosis and management of (CVT) can be challenging given the diversity of causes and risk factors with a wide range of symptoms and signs. At least one identifiable risk factor was found in 85% of patients of the (ISCVT) study while multiple predisposing factors were found in 44%. The most common risk factors were oral contraceptives and inherited and acquired thrombophilia conditions.

the most common symptom is headache. It is found in 90% of patients with (CVT) usually associated with focal neurological symptoms or seizures. Isolated headaches account only for 15% of patients.

diagnosis of (CVT) depends on high level of clinical suspicion followed by neuroimaging (preferably some specific MRI modalities).

Anti-coagulation is the standard of treatment for patients with (CVT) based on small randomized clinical trials and reviews and wide consensus opinion of most experts.There is still no solid evidence from large randomized clinical trials. It is thought that anticoagulation may stop growth of the thrombus and permit recanalization mechanisms . it also may hinder other thrombotic events.

A trial compared an adjusted doses of intravenous unfractionated heparin (UFH) with placebo was stopped early after 20 of the planned 60 patients were enrolled because there was an obvious benefit of treatment.

Based on consensus, current recommendations for the duration of anticoagulation in patients with (CVT) are dependent mainly on the presence of provoking factor/s which may be transient or persistent. Thus duration ranges from 3 to 6 months for reversible causes (e.g. OCP) of provoked (CVT) to indefinite treatment period of anticoagulation for recurrent unprovoked (CVT) or severe thrombophilia state. Traditionally, warfarin is used after a bridging period of Heparins with INR target 2.0 to 3.0.

Rivaroxaban is a selective reversible anti-Factor X anticoagulant, that has a good bioavailability, much predictable pharmacokinetics, and maybe a lower risk for major bleeding in comparison to warfarin. Therefore, laboratory monitoring and dose adjustments are almost unnecessary. However, rivaroxaban has not been thoroughly studied for CVT.

The objective of the study:

To compare warfarin to rivaroxaban in CVT patients in terms of short and long term outcomes, and complications.

Methods:

planned sample: 60 patients. study design: Subjects will be enrolled from Damascus University hospitals (Almouassat University hospital, and Alassad University hospital) and Almujtahed (Damascus public hospital) and randomly assigned to the two arms of the study (rivaroxaban or warfarin) using web-based random number generator application called "Research Randomizer. The warfarin arm will serve as the control group. No blinding will be applied due to safety and ethical issues.

Subjects will be followed up monthly for 6 months to evaluate clinical outcomes.

Subjects confirmed to have elevated intracranial pressure (ICP) will receive Acetazolamide 500 mg (bid) for two weeks then will be tapered gradually if possible as needed.

Concomitant use of any anticonvulsants will be recorded for further sub-groups analysis.

Used measures:

• Sinus venous thrombosis severity scale (SVTSS)
• Patient's independency using Barthel index.
• intracranial pressure (ICP) using fundoscopy, or direct ICP measuring.
• diagnostic DSA, CT and MRI scans.
• Hemoglobin level for hemorrhagic complications.
• INR test to adjust the warfarin doses.

Quality assurance plan, Data checks, and Source data verification:

The data will be collected by the investigators directly from the patients, their families, and their medical records. at least two investigators will evaluate each patient to affirm objective and accurate assessment of outcome measures. The data will be entered manually after collection into a Google Forms page that contains fields of all the required data, which will automatically produce the corresponding Excel sheet. The principal investigator will review and double-check the collected data and comparing the final excel sheet with patients' data collected from patients and their surrogates' interviews, their medical files, imaging reports, and chats.

Plan for Data Analysis:

Percentages for nominal input, Medians for clinical scores. For continuous outcomes, the investigators will use Mann Whitney test for two-group data, and Kruskal Wallis for 3+ data groups. Nominal outcomes: Chi-square when the assumptions apply, and Fisher exact test when they don't. The analysis will be done using SPSS 25 software primarily, along with EXCEL.

Missing data will be treated as per the professional statistical methods.

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Appendix 1:

To avoid any subjective bias, the investigators will define each element of (SVTSS) scale as the following:

● headache severity will be scaled depending on the "Functional Pain Scale (FPS)" as Slight (2), Moderate (4 - 6), Severe (8 - 10).

functional pain scale detailed as follows: 0: No pain. 2: Tolerable, activities not prevented. 4: Tolerable prevents some activities. 6: Intolerable prevents many active (not passive) activities. 8: Intolerable, prevents all active and many passive activities. 10: Intolerable incapacitated, unable to do anything or speak due to pain.

Active activities: usual activities or those requiring effort (turning, walking, etc.) Passive activities: talking on phone, watching TV, reading

● Focal signs:

• Transient: lasting less than 24 hours.
• Mild paresis: any degree of minimal persistent weakness that can only be noticed by comparing with the other side.
• Moderate paresis: obvious weakness but still can move limb against gravity.
• Severe Paresis: any limb movement but not against gravity or complete plegia.

The investigators will consider any other focal neurologic sign (e.g. cranial nerve lesions or palsies) as a focal paresis and will be scaled as mild if minimal defect, moderate if obvious defect, and severe if leads to functional disability (e.g. visual loss). The investigators will except abducens nerve palsies from scaling and consider any degree of diplopia as "Mild paresis".

If multiple focal neurologic deficits are present. Patients will be scored upon the most severe focal sign.

● Seizures: the investigators define seizure as a clinical convulsive seizure.

Obvious other cause/s of seizure/s not related to a new complication of the disease or anticoagulation treatment (e.g. poor compliance with anticonvulsant drugs) will not affect the severity scale (i.e. changing SVTSS score).

● Consciousness: depending on Dorland's Illustrated Medical Dictionary 32nd edition the investigators define:

• Confusion: disturbed orientation in regard to time, place, or person.
• Psychosis: a mental disorder characterized by gross impairment in reality testing as evidenced by delusions, hallucinations, markedly incoherent speech, or disorganized and agitated behavior.
• Somnolence: drowsiness or sleepiness, particularly in excess.
• Stupor: a lowered level of consciousness manifested by the subject's responding only to vigorous stimulation.
• Coma: a state of unconsciousness from which the patient cannot be aroused, even by powerful stimulation.
• Dead: destitute of life.

Any new/worsening focal sign, new/relapsing seizure/s, or deterioration in the level of consciousness will be documented and promptly investigated as a probable worsening in severity scale due to disease (i.e. CVT) or treatment complication/s (e.g. intracranial hemorrhage) and will prompt emergent evaluation and repeating neuroimaging as needed.

Inclusion criteria

• patients aged 14 years or older and weighing more than 50 kg.
• Recent diagnosis of symptomatic cerebral venous thrombosis confirmed by MRI modalities, CT venography, or conventional angiography.

Exclusion criteria

• Any absolute contraindication to anticoagulation.
• Impaired renal function (CrCl < 30 mL/min using Cockcroft-Gault equation).
• Pregnancy or lactation at randomization.
• mandatory other blood thinners use (e.g. Aspirin).