Title:

Optimal Delay Time to Initiate Anticoagulation after Ischemic Stroke in Atrial Fibrillation (START): a pragmatic, adaptive randomized clinical trial.

Primary Objective:

• To determine the optimal time to initiate anticoagulation with a Non-Vitamin K Oral Anticoagulant (NOAC) after ischemic stroke in patients with non-valvular atrial fibrillation.

Secondary Objectives:

• To compare the rates of primary adverse outcomes in a per protocol analysis
• To compare 30 day clinical outcomes by the modified Rankin scale among the time-to-treatment groups
• To compare 90 day clinical outcomes by the modified Rankin scale among the time-to-treatment groups
• To explore the optimal timing in subgroups of age, sex, outcome category, and NOAC choice

Long-term oral anticoagulation is standard for secondary stroke prevention in patients with atrial fibrillation (AFib). However, there is limited data and no consensus on the timing of when to initiate anticoagulation therapy, and concern that starting too soon risks symptomatic hemorrhagic transformation. These data are derived almost exclusively from heparins and Vitamin K antagonists (e.g.,warfarin). Now that NOACs have become the mainstay of stroke prophylaxis in AFib and have more rapid and consistent anticoagulation and fewer strokes (hemorrhagic especially), the question of optimal timing of NOAC initiation is of increasing importance.

The primary aim is to determine the time-to-treatment interval with the lowest associated risk for adverse events in the context of anticoagulation therapy with NOACs for acute stroke patients with non-valvular AFib. The question will be investigated with a prospective, adaptive, randomized, controlled "dose-exploration" trial with the time to treatment with NOAC therapy treated as the incremental "dose".

An adaptive, pragmatic trial will be performed that will not deviate from the treating physicians' usual practice except for randomizing the time to start the NOAC. Data collection will be limited to those fields necessary for the planned primary and secondary analyses.

The composite primary outcome event will be any of the following within 30 days of the index stroke: Ischemic Events (symptomatic ischemic stroke or systemic embolism) or Hemorrhagic Events (symptomatic hemorrhagic transformation of index ischemic stroke, other symptomatic intracranial hemorrhage, or major extracranial hemorrhage).

Four time-to-treatment intervals, i.e. study arms, between 2 and 14 days will be investigated: 72 (+/- 24) hours, 132 (+/- 12) hours, 228 (+/- 12) hours, and 324 (+/- 12) hours. An innovative adaptive design will be used which includes response adaptive randomization and modeling of ischemic and hemorrhagic outcome events. The ischemic and hemorrhagic events within the composite primary endpoint are modeled separately using their known monotonic property that the risk of an event increases (ischemic) or decreases (hemorrhage) as the time-to-treatment interval lengthens. Interim analysis will occur after 100 subjects are randomized and have the primary outcome, where the primary outcome will be analyzed and new randomization probabilities will be calculated to favor the arms that have a better risk-profile. Thereafter, interim analyses will occur after 50 subjects are randomized under the new randomization probabilities, and further new randomization probabilities will be calculated to favor the arms that have a better risk-profile.

Inclusion Criteria:

1. New disabling neurological deficit attributable to new ischemic stroke.

2. Minimum lesion diameter of 1.5cm on qualifying imaging. If lesion not visible on imaging, NIHSS must be greater than 4.

3. Non-valvular atrial fibrillation (paroxysmal, persistent, or permanent).

4. Not currently anticoagulated and/or will not be anticoagulated prior to starting their NOAC at the randomized time of initiation (except for DVT prophylaxis).

   Note: Patients who had been taking an anticoagulant prior to their qualifying index event (for any reason) are eligible for START, assuming the drug is no longer having a therapeutic effect in the patient's system by 48 hours from stroke onset.

5. Treating physician plans to anticoagulate with a FDA-approved novel oral anticoagulant (NOAC): apixaban, dabigatran, edoxaban, or rivaroxaban, or other FDA-approved NOAC.

6. Qualifying brain CT or MRI scan < 48hr from stroke onset (time last known well). If patient has been treated with thrombolytic or endovascular therapy for this stroke, then the qualifying scan is that which is performed after therapy to rule out clinically significant hemorrhagic transformation.

7. Ability to randomize within 60 hours of symptom onset.

Exclusion Criteria:

1. Any clinical or imaging evidence of spontaneous intracranial hemorrhage in the previous 6 months.

   Note: Patients with hemorrhagic transformation of current or previous ischemic stroke may be included per Investigator's judgment. Sporadic microbleeds may be included per Investigator's judgment. As a general recommendation, a cerebral microbleed is considered to be ≤ 5mm, but sometimes up to 10mm, in greatest diameter on gradient recalled echo (GRE), or T2*, MRI sequences. Any blood visualized on a CT will be classified as a macrobleed.

2. Infarct volume (estimated) is greater than 50% of middle cerebral artery territory on qualifying scan. If the full extent of the lesion is not visible, any patient with a NIHSS > 23 must be excluded.

   Note: The lesion does not need to be restricted to the mCA, but if the lesion volume is estimated to be greater than half of the mCA territory, the patient should be excluded.

   Note: In non-EVT patients, any NIHSS following the index stroke may be used to qualify the patient for START. For example, a patient that presents with a NIHSS of 10 who then receives tPA and improves to a NIHSS of 2 is still eligible for START. For patients whom had endovascular therapy, the qualifying NIHSS assessment is that which is obtained with their qualifying scan following therapy.

3. Anticipated need for major surgery over the next 30 days that would require delay, discontinuation, or extended suspension of anticoagulant of more than 5 days.

4. Symptomatic edema expected from size and location of ischemic stroke.

5. Decreased level of consciousness present or expected.

6. Life expectancy less than 90 days.

7. Follow-up in person or by telephone for 90 days is not feasible.