Predicting mortality risk in hospitalized ACS patients with hypertensive comorbidity: an interpretable machine...

Hypertension serves as a prevalent health issue, particularly in South Asia, where it is also a risk factor and comorbidity that affects the prognosis of Acute Coronary Syndrome (ACS) by increasing the likelihood of complications such as heart failure and arrhythmias. Conventional tools for predicting ACS mortality risk, such as the TIMI and GRACE scores, often fail to adequately represent the Asian population and do not specifically address the needs of ACS patients with comorbid hypertension. Our study focuses on developing a tailored and interpretable risk prediction model to assess mortality rate of Asian ACS-hypertensive patients.

We used in-hospital data from the NCVD Registry, which includes ACS patients with hypertension from 2006 to 2019 and selected key factors such as demographics, medications, and clinical details using Sequential Backward Elimination. We then used various ML techniques and combined them with ensemble meta-learners to predict mortality. We measured the model's accuracy using the area under the curve (AUC) and fine-tuned the best model with Platt Scaling. Our model was compared with the TIMI score to calculate the net reclassification index (NRI). Finally, we applied LIME and SHAP to understand feature importance and interpret model performance.

The RF model with selected 28 features outperforms other prediction models with an AUC of 0.95. The calibrated RF model has raised Brier score (ACS: 0.046; STEMI: 0.051; NSTEMI: 0.041), and Chi-squared (ACS: 10.253; STEMI: 6.023; NSTEMI: 23.030). NRI verified our calibrated model's better reclassification than the conventional TIMI risk score (improved accuracy by 15%-78%). The model's robustness was proven by its greater AUC (0.841-0.898) than the TIMI risk score (0.641-0.83). SHAP and LIME analyses revealed that the Killip classification and peak CK levels significantly influenced mortality. Conversely, ACE medications were found to be more strongly associated with survival.

Our calibrated RF model demonstrated superior predictive accuracy in mortality risk for Asian hypertensive ACS patients, outperforming traditional TIMI scores. It efficiently identified key mortality predictors, which is further interpreted by SHAP and LIME, effectively underscore the significance of selected features for ACS mortality risk.