From Crisis to Complications: A Nationwide Cohort Study Assessing One-Year Cardiovascular and Thromboembolic Risks After Severe COVID-19 Compared to Matched Controls

<b>Background:</b> The long-term risk of cardiovascular and thrombotic events following severe COVID-19 remains largely unknown. This study aimed to assess the risk of atherosclerotic cardiovascular disease (ASCVD) within one year after hospital discharge in patients who received intensive care for severe COVID-19. <b>Methods:</b> A register-based nationwide case-control study on a cohort of patients with severe COVID-19 (cases) requiring mechanical ventilation and discharged alive without experiencing cardiovascular or thrombotic events during their hospital stay. Each case was matched (age, sex, district of residence) with up to 10 population-based controls. The primary outcome was ASCVD occurring after hospital discharge, defined as a composite endpoint, including myocardial infarction (MI), unstable angina pectoris and ischemic stroke. Secondary endpoints were MI, stroke, all-cause mortality, and venous thromboembolic events. Hazard ratio (HR) (95% CI) was used with adjustments for age, sex, socioeconomic factors, and co-morbidities. <b>Results:</b> In total, 31,375 individuals (70% men, median age 62 years) were included, of which 2854 had severe COVID-19 and 26,885 matched control subjects. The adjusted HR for ASCVD during the first year compared to control subjects was 3.1 (95% CI 1.7-5.4). Adjusted HRs for secondary outcomes for myocardial infarction were 2.0 (95% CI 0.8-5.3), for stroke 1.9 (95% CI 0.7-5.3), for pulmonary embolism 49.4 (95% CI 28.0-87.1), and deep venous thrombosis (DVT) 16.0 (95% CI 7.8-32.6). <b>Conclusions:</b> Severe COVID-19 requiring intensive care was associated with a substantial increase in 1-year risk for ASCVD and venous thromboembolic events.