Abstract Body (Do not enter title and authors here): Purpose: To evaluate the effectiveness of a heart attack education intervention (Heart Matters) in communities with elevated cardiovascular (CV) risk and low emergency medical service (EMS) use for acute coronary syndrome (ACS).
Study Design and Methods: A stepped-wedge cluster randomized trial was conducted in eight high-risk communities (Dec 2021–Mar 2023), with clusters transitioning every four months; a parallel program evaluation was also conducted.
Sample Size: 1,775 ACS patients (primary outcome).
Population: ACS patients who resided in intervention communities.
Intervention(s): The intervention included a heart attack education program delivered by Coordinators (n= 10,088 on 490 occasions), household mailouts (n=174,110 households), opportunistic media, and a 1-month geo-targeted social media campaign.
Power Calculations: A sample size of 2,240 ACS patients provided 80% power to detect an 11% absolute increase in EMS use (expected baseline=61%).
Primary End Points: The proportion of ACS patients using EMS.
Secondary End Points: Included patient and prehospital delay.
Main Results: Among 1,775 ACS patients (865 intervention, 910 control), baseline EMS use was higher than expected, and fewer in the intervention period arrived via EMS (68.6% vs. 63.4%; adjusted risk difference [RD] –8.98%; 95%CI: –17.50, –0.46). Decreased EMS use was more pronounced in metropolitan areas (RD -10.73; 95% CI: -20.43, -1.03) and among individuals impacted by a major flooding event (RD -13.50; 95% CI: -26.52, -0.47), compared to rural areas (RD -3.67; 95% CI: -15.46, 8.11) and those not impacted by flooding (RD -6.44; 95% CI: -15.96, 3.08). However, estimates of interaction terms were uncertain (p = 0.25 for metro/rural; p = 0.32 for flooding impact). Among STEMI and ACS patients undergoing revascularisation, fewer in the intervention group sought medical attention within 60 minutes (STEMI: RD -30.78%, 95%CI: -47.74, -13.82) and presented to hospital within 120 minutes (ACS: RD -23.14, 95%CI: -35.98, -10.30). Coordinators reported responding to public concerns about media reports of EMS and Emergency Department demand and wait times throughout the intervention.
Conclusion: The Heart Matters intervention did not improve EMS use or reduce prehospital delay in regions with high cardiovascular risk. External systemic factors may have outweighed the effects of community education, suggesting that alternative or more targeted strategies may be needed in these communities.