Incidence of acute coronary syndrome during national lock-down: Insights from nationwide data during the Coronavirus disease 2019 (COVID-19) pandemic.

Background: Urgent recognition and treatment are needed in patients with acute coronary syndrome (ACS), however this may be difficult during the Coronavirus disease 2019 (COVID-19) pandemic with a national lock-down. We aimed to examine the incidence of ACS after national lock-down.

Methods: The Danish government announced national lock-down on March 11, 2020 and first phase of reopening was announced on April 6. Using Danish nationwide registries, we identified first-time ACS admissions in (1) January 1 to May 7, 2017-2019, and (2) January 1, 2020 to May 6, 2020. Incidence rates of ACS admissions per week for the 2017 to 2019 period and the 2020 period were computed and incidence rate ratios (IRR) were computed using Poisson regression analysis.

Results: The number of ACS admissions were 8,204 (34.6% female, median age 68.3 years) and 2,577 (34.0% female, median age 68.5 years) for the 2017 to 2019- and 2020 period, respectively. No significant differences in IRRs were identified for weeks 1 to 9 (January 1 to March 4) for 2020 compared with week 1 to 9 for 2017 to 2019. In 2020, significant lower IRRs were identified for week 10 (March 5 to 11) IRR = 0.71 (95% confidence intervals [CI]: 0.58 to 0.87), week 11 (12 to 18 March) IRR = 0.68 (0.56 to 0.84), and week 14 (April 2 to April 8) IRR = 0.79 (0.65 to 0.97). No significant differences in IRRs were identified for week 15 to 18 (April 9 to May 6). In subgroup analysis, we identified that the main result was driven by male patients, and patients ≥60 years.

Conclusions: During the COVID-19 pandemic with an established national lock-down we identified a significant decline around 30% in the incidence of ACS admissions. Along with the reopening of society, ACS admissions were stabilized at levels equal to previous years.