Out-of-hospital sudden cardiac arrest (SCA) is a major public health problem with mortality >90%, and incidence has increased during the COVID-19 pandemic. Information regarding ethnicity-specific effects on SCA incidence and survival is lacking. Methods: In a prospective, population-based study of Ventura County, CA residents (2020 Pop. 843,843; 44.1% Hispanic), we compared SCA incidence and outcomes during the first two years of the COVID-19 pandemic to the prior four years, overall and by

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... nicity (Hispanic vs non-Hispanic). Findings: Of 2,222 OHCA cases identified, 907 occurred during the pandemic (March 2020 - Feb 2022) and 1315 occurred pre-pandemic (March 2016 - Feb 2020). Overall age-standardized annual SCA incidence increased from 38.9/100,000 [95% CI 36.8-41.0] pre-pandemic to 53.8/100,00 [95% CI 50.3 - 57.3, p<0.001] during the pandemic. Among Hispanics, incidence increased by 77%, from 38.2/100,00 [95% CI 33.8-42.5] to 67.7/100,00 [95% CI 59.5-75.8, p<0.001]. Among non-Hispanics, incidence increased by 26% from 39.4/100,000 [95% CI 36.9-41.9, p<0.001] to 49.8/100,00 [95% CI 45.8-53.8]. SCA incidence rates closely tracked COVID-19 infection rates. During the pandemic, SCA survival was significantly reduced (15.3% to 10.0%, p<0.001) and Hispanics were less likely than non-Hispanics to have bystander CPR (44.6% vs. 54.7%, p=0.005) and shockable rhythm (15.3% vs. 24.1%, p=0.003). Interpretation: Hispanic residents experienced higher SCA rates during the pandemic with less favorable resuscitation profiles. These findings implicate potential ethnicity-specific barriers to acute care and represent an urgent call to action at the community and health-system levels. Funding: National Heart Lung and Blood Institute Grants R01HL145675 and R01HL147358.