Heart Attack Education and EMS Response in High-Risk, Low EMS Usage Areas: A Stepped-Wedge Cluster-Randomized Trial.

Importance: Patient delays in recognizing and acting on acute coronary syndrome (ACS) symptoms worsen outcomes. Objective: To evaluate the effectiveness of a heart attack education intervention (Heart Matters) aiming to improve recognition and response to ACS symptoms in communities with elevated cardiovascular risk and low emergency medical service (EMS) use. Design, Setting, and Participants: This stepped-wedge cluster randomized clinical trial was conducted in 8 high-risk communities (local government areas; 4 metropolitan and 4 rural with a combined population of approximately 792 000 adult residents) in Victoria, Australia (December 2021 to March 2023 with follow-up to March 2024), with clusters crossing to the intervention every 4 months. Data were obtained from administrative datasets and registries (analysis complete June 2025). Intervention: A multicomponent community education program including 490 community sessions (approximately 10 088 residents), more than 174 110 households mailouts, more than 50 000 resource handouts, opportunistic media, and a geotargeted social-media campaign (reach of approximately 350 000 residents). The control period did not include any educational campaign. Main Outcome and Measures: The primary outcome was the proportion of patients with ACS transported to hospitals by EMS, as recorded in the Victorian Emergency Minimum Dataset. Outcomes were analyzed at the patient level using mixed-effects regression models, reporting risk differences (RDs) and odds ratios (ORs). A program evaluation was also conducted to assess implementation and inform potential replication and scale-up. Results: Among 1775 patients with ACS (865 intervention and 910 control; 924 [52.1%] aged ≥65 years; 1193 male [67.2%]), EMS use was unexpectedly high during the initial control period, coinciding with a COVID-19 wave. EMS transport occurred in 624 of 910 patients with ACS (68.6%) in the control period and 548 of 865 patients (63.4%) in the intervention period (adjusted RD, -8.98%; 95% CI, -17.50% to -0.46%; P = .04; adjusted OR, 0.67; 95% CI, 0.45 to 1.01; P = .05). Reductions were more pronounced in metropolitan areas (RD -10.73%; 95% CI -20.43% to -1.03%) and during a severe flooding event (RD -13.50%; 95% CI -26.52% to -0.47%). Early treatment-seeking was also lower, although estimates were imprecise. The program evaluation identified COVID-19 pandemic and seasonal impacts, as well as community concerns regarding EMS costs, demand, and wait times. Conclusions and Relevance: In this community ACS education trial conducted in high-risk regions, the intervention did not improve EMS use or prehospital care-seeking. External contextual factors, including the COVID-19 pandemic and natural disasters, appeared to influence patient behavior and may have attenuated intervention effects, highlighting the complexity of achieving behavioral change through community education alone. Trial Registration: ClinicalTrials.gov Identifier: NCT04995900.