Common ECG abnormalities pose increased risks of out-of-hospital cardiac arrest

Abstract Background It is known that 40%-60% of all sudden cardiac deaths occur as the first sign of unrecognized heart disease which poses a challenge in preventing early cardiac death (1). While many common ECG abnormalities have previously been associated with an increased risk of cardiac morbidity and mortality, knowledge of what abnormalities are associated with out-of-hospital cardiac arrest (OHCA) is lacking (2,3). Purpose To investigate the association between a range of common ECG abnormalities and the risk of subsequent OHCA. Methods From 2000 to 2020, patients acquiring an ECG at a Danish hospital or in an ambulance in Denmark were followed until either having OHCA, emigrating, death from other causes or end of study (01-01-2021), whichever came first. Only the index ECG and first occurrence of OHCA for each patient were considered for analysis. Data on patient age and gender were obtained through the Danish Civil Registration System. A multivariable Cox regression, adjusted for patient gender and age at ECG acquisition, was performed to assess the risk (hazard ratio [HR] with 95% confidence interval [95% CI]) of OHCA for various common ECG abnormalities. P-values less than 0.05 were considered significant. Results In total 2,037,003 patients were included, of which 26,446 (13.0%) had OHCA during follow-up after ECG acquisition. Patient characteristics and distribution of ECG abnormalities between the OHCA and non-OHCA patients are shown in Table 1. Patients with OHCA were older and more frequently male (both p < 0.001). ECG abnormalities were also generally more frequent among OHCA patients than non-OHCA patients. Median follow-up time for the entire cohort was 2063 days. The results of the multivariable Cox regression are shown in Figure 1. All assessed ECG abnormalities resulted in significantly higher risk of later OHCA with HR (95% CI) ranging between 1.0521 (1.0512-1.0531) and 1.0554 (1.0544-1.0563) when also adjusting for patient age and gender. Conclusion Common ECG abnormalities were associated with a significantly increased risk of OHCA. Further research is needed to investigate the mechanisms behind specific ECG abnormalities and OHCA occurrence and to determine the validity of ECG screening in preventing OHCA.Table 1Figure 1, SL = Sokolow-Lyon