The resting 12-lead electrocardiogram (ECG) is a widely used diagnostic tool in modern medicine, providing crucial insights into various heart conditions. Recently, the application of Artificial Intelligence (AI) to infer health-related information from the 12-lead ECG has gained significant interest. In this study, we propose a deep-learning approach to predict sex and age from both 12-lead and reduced-lead ECGs (12L, 6L, 4L, 3L, 2L, and 1L), and analyze their implications for predicting patient mortality. We employed a ResNeXt-based architecture and trained our model using the CODE15 dataset. Our best sex prediction model achieved an F1-score of 0.800 ± 0.007, Sensitivity (Se) of 0.807 ± 0.016, Positive Predictive Value (PPV) of 0.793 ± 0.022, and an Area Under the Curve (AUC) of 0.910 ± 0.007 when using the 12-lead ECG configuration. Similarly, our best age estimation model achieved a mean absolute error (MAE) of 8.961 ± 0.180, a Pearson Correlation (ρ) of 0.810 ± 0.004, and a coefficient of determination (R2) of 0.637 ± 0.014 when using the 4-lead ECG configuration. Through the evaluation of different lead-set configurations, we demonstrated that even with a reduced number of leads, our models achieved comparable performance to those ob- tained using the conventional 12-lead ECG setup. Moreover, we found that the mortality risk, assessed by the hazard ratio (HR), increased when our age model predicted an age higher than the actual age by a certain threshold for all lead sets (12L: 2.49, 6L: 2.17, 4L: 2.53, 3L: 2.54, 2L: 2.76, 1L: 2.65). Likewise, when our model misclassified the patient’s actual sex, the mortality risk also increased (12L: 1.36, 6L: 1.26, 4L: 1.38, 3L: 1.33, 2L: 1.20, 1L: 1.12). Additionally, we observed a decrease in mortality risk when our method predicted an age lower than the actual age by a certain threshold (12L: 0.71, 6L: 0.71, 4L: 0.74, 3L: 0.71, 2L: 0.75, 1L: 0.64). Overall, our research shows the efficacy of reduced lead ECGs in predicting age, determining sex, and providing valuable insights into patient mortality.
