Dynamic Risk Trajectories for Sudden Cardiac Arrest: The Role of Recurrent Cardiovascular Events

Background Emerging evidence suggests that dynamic risk assessment may enhance sudden cardiac arrest (SCA) risk stratification. While cardiovascular events, including acute coronary syndrome (ACS) and heart failure (HF) hospitalization, are associated with increased SCA risk, the impact of recurrent events on subsequent SCA risk in a contemporary, real-world population is unknown. This study aimed to assess whether patients with a first-time ACS or HF hospitalization who experience a recurrent cardiovascular event have higher risk of SCA compared to those who do not. Methods The Observational Study of Cardiac Arrest Risk (OSCAR) is a prospective cohort study with adjudicated SCA outcomes. In the current study, patients who survived a first ACS or HF hospitalization were categorized into index ACS or HF cohorts. Participants were followed for recurrent cardiovascular events and SCA. Associations between recurrent events and SCA were assessed using Cox models with recurrent event modeled as a time-dependent variable. Findings were validated in the Framingham Heart Study (FHS). Results In the OSCAR discovery cohort, 2946 patients experienced an index ACS event. The incidence rate of SCA was higher following a recurrent ACS event than without (3.70 vs 1.28 per 100 patient-years). Recurrent ACS event was associated with a significantly higher risk of SCA (adjusted HR 3.15, 95% CI 2.06-4.83, p<0.0001). A total of 6711 patients experienced an index HF hospitalization, and the incidence rate of SCA was higher following a recurrent HF event than without (1.35 vs 0.97 per 100 patient-years). Recurrent HF hospitalization was associated with a significantly higher risk of SCA (HR 1.81, 95% CI 1.46-2.26, p<0.0001). In the FHS validation cohorts a recurrent event during follow-up was associated with a significantly higher risk of SCA in the ACS cohort (HR 2.85, 95% CI 1.66-4.90, p=0.0002), but the association was not statistically significant in the HF cohort (HR 1.49, 95% CI 0.73-3.03, p=0.27). Conclusion Recurrent ACS event was associated with more than threefold higher risk of SCA, and a recurrent HF hospitalization with 80% higher risk of SCA. These findings suggest that dynamic clinical trajectories of recurrent cardiovascular events may inform management and prevention of SCA. Clinical Perspective What is new? In patients with a first acute coronary syndrome (ACS), those with a recurrent ACS event during follow-up had a threefold higher risk of sudden cardiac arrest (SCA) compared with patients without recurrence. Among patients hospitalized for heart failure (HF) for the first time, those with a subsequent HF hospitalization had nearly double the risk of SCA compared with those without recurrence. What are the Clinical Implications? These findings indicate that individuals with recurrent cardiovascular events are at higher risk of sudden cardiac arrest. These dynamic risk trajectories may inform management of these patients as well as improved prevention of sudden cardiac arrest. Future prospective studies are needed to test these findings in larger and more diverse populations.