Objectives: Despite the currently prevailing, milder Omicron variant, coronary artery disease (CAD) patients constitute a major risk group in COVID-19, exhibiting 2.6 times the mortality risk of non-CAD patients and representing over 22% of non-survivors. No data are currently available on the efficacy of antibody levels in CAD patients, nor on the relevance of vaccination status versus antibody levels for predicting severe courses and COVID-19 mortality. Nor are there definitive indicators to assess if individual CAD patients are sufficiently protected from adverse outcomes or to determine the necessity of booster vaccinations. Methods: A prospective, propensity-score-matched, multicenter cohort study comprising 249 CAD patients and 903 controls was conducted. Anti-SARS-CoV-2-spike antibodies were measured on hospital admission. Prespecified endpoints were in-hospital mortality, intensive care, and oxygen administration. Results: After adjustment for potential confounders, CAD patients exhibited 4.6 and 6.1-times higher mortality risks if antibody levels were <1200 BAU/mL and <182 BAU/mL, respectively, compared to CAD patients above these thresholds (aOR 4.598, 95%CI 2.426–8.714, p < 0.001; 6.147, 95%CI 2.529–14.941, p < 0.001). Risk of intensive care was 3.7 and 4.0 (p = 0.003; p < 0.001), and risk of oxygen administration 2.6 and 2.4 times higher below these thresholds (p = 0.004; p = 0.010). Vaccination status was a weaker predictor of all three outcomes than both antibody thresholds. Conclusion: Antibody levels are a stronger predictor of outcome in CAD patients with COVID-19 than vaccination status, with 1200 BAU/mL being the more conservative threshold. Measuring anti-SARS-CoV-2 antibodies in CAD patients may ensure enhanced protection by providing timely booster vaccinations and identifying high-risk CAD patients at hospital admission.
