Predictive value of the NORPACS score for malignant ventricular arrhythmias in STEMI patients undergoing primary PCI

Malignant ventricular arrhythmias (MVA)-sustained ventricular tachycardia or fibrillation-remain a major early complication after ST-segment elevation myocardial infarction (STEMI) despite timely reperfusion. The no-reflow phenomenon is a key substrate for arrhythmogenesis. The no-reflow prediction in acute coronary syndrome (NORPACS) score, originally developed to predict no-reflow, may also help identify patients at high arrhythmic risk.

We retrospectively analyzed 1050 consecutive STEMI patients undergoing successful primary percutaneous coronary intervention (PCI) between January 2020 and December 2024. The primary endpoint was inhospital MVA. Univariable and multivariable logistic regression models were constructed incorporating clinical, laboratory, and angiographic variables. The incremental predictive value of the NORPACS score was assessed using receiver operating characteristic analysis, net reclassification improvement (NRI), and integrated discrimination improvement (IDI). Kaplan-Meier and restricted cubic spline analyses evaluated temporal risk patterns.

MVA occurred in 79 patients (7.5%), all within the first 8-h post-PCI. Patients with MVA more often had diabetes, anterior infarcts, lower LVEF, higher inflammatory markers, and no-reflow. The NORPACS score was significantly higher in the MVA group (7.1 ± 1.3 vs. 6.2 ± 1.7, p < 0.001) and independently predicted events across all multivariable models (adjusted OR range: 1.20-1.44, all p < 0.05). Adding NORPACS to clinical-laboratory models improved discrimination (ΔAUC up to 0.07) and yielded significant IDI (0.022-0.024) and NRI (0.10-0.14). Kaplan-Meier curves confirmed earlier arrhythmia onset with higher scores.

The NORPACS score is an independent and incremental predictor of early MVA in STEMI patients undergoing PCI. Its integration into clinical-laboratory risk models enhances risk stratification and may guide intensified monitoring in high-risk patients. Prospective multicenter validation is warranted.