Poster The Joint Annual Meeting of the Stroke Society of Australasia (SSA) and Smartstrokes 2023

INTEnsive ambulance-delivered blood pressure Reduction in hyper-Acute stroke Trial (INTERACT4): Progress Update and Experiences During COVID (#211)

Chen Chen 1 2 3 , Yapeng Lin 4 5 , Feifeng Liu 3 , Xiaoying Chen 1 , Laurent Billot 1 , Qiang Li 1 , Hisatomi Arima 1 6 , Philip M Bath 7 , Gary A Ford 8 , Thompson Robinson 9 , Else Charlotte Sandset 10 11 , Jeffrey L. Saver 12 , Nikola Sprigg 7 , H. Bart van der Worp 13 , Lili Song 1 2 , Gang Liu 14 , Jie Yang 15 16 , Gang Li 3 , Craig Anderson 1 2
  1. The George Institute for Global Health, Faculty of Medicine, UNSW, Sydney, Australia
  2. The George Institute for Global Health China, Beijing, China
  3. Department of Neurology, Shanghai East Hospital, School of Medicine, Tongji University , Shanghai, China
  4. Department of Neurology, Clinical Medical College and The First Affiliated Hospital of Chengdu Medical College, Chengdu, China
  5. International Clinical Research Center, Chengdu Medical College, Chengdu, China
  6. Department of Preventive Medicine and Public Health, Faculty of Medicine, Fukuoka University , Fukuoka, Japan
  7. Stroke Trials Unit, Mental Health & Clinical Neuroscience, University of Nottingham, Nottingham, UK
  8. Oxford University Hospitals NHS Foundation Trust and University of Oxford, Oxford, UK
  9. College of Life Sciences and NIHR Leicester Biomedical Research Centre, University of Leicester , Leicester, UK
  10. Department of Neurology, Oslo University Hospital, Oslo, Norway
  11. Norwegian Air Ambulance Foundation, Norway
  12. University of California, California, USA
  13. University Medical Center Utrecht, Utrecht, Netherlands
  14. Clinical Medical College and The First Affiliated Hospital of Chengdu Medical College, Chengdu, China
  15. Department of Neurology, Sichuan Provincial People's Hospital, University of Electronic Science and Technology of China, Chengdu, China
  16. Sichuan Provincial Key Laboratory for Human Disease Gene Study, Chengdu, China

Background: Uncertainty exists regarding the effects of pre-hospital (ambulance) initiated blood pressure (BP) lowering.

Aims: We initiated the INTEnsive ambulance-delivered blood pressure Reduction in hyper-Acute stroke Trial (INTERACT4) to determine the effectiveness and safety of intensive BP lowering in patients with suspected acute stroke.

Methods: An ongoing multi-centre, ambulance-delivered, prospective, randomised, open-label, blinded endpoint trial of pre-hospital-initiated BP lowering in hypertensive patients with suspected acute stroke in regions of China. Patients are randomised through a mobile phone digital system to intensive (target systolic BP [SBP] <140mmHg within 30 min) or guideline-recommended BP management according to local protocols. Primary outcome is level of disability at 90 days, assessed by an ordinal analysis of the modified Rankin scale. The sample size was reduced from 3116 to 2320 in 2022 as the stroke mimic rate is lower than expected (6% vs. 30%).

Results: Between March 2020 and April 2023, 2053 patients were recruited: 45.0% intracerebral haemorrhage and 5.1% stroke mimic. Recruitment slowed during the COVID outbreak in 2022, and nearly stopped in Shanghai during the lockdown period, but has subsequently picked up such that we expect to reach the recruitment target in late 2023. The operation team faced travel restrictions due to COVID, resulting in entry delays and missing data, requiring a shift towards remote monitoring and online training. Good BP differences have been achieved between randomized groups, being greater in those with intracerebral haemorrhage without any safety concerns being noted.

Conclusions: As the largest ambulance trial in stroke, INTERACT4 will provide reliable evidence on the effectiveness and safety of very early intensive BP lowering in patients with suspected acute stroke.

Trial registration: ClinicalTrials.gov NCT03790800. Registered on 2 January 2019; Chinese Trial Registry ChiCTR1900020534. Registered on 7 January 2019.