Artificial Neural Network Modeling Enhances Risk Stratification and Can Reduce Downstream Testing for Patients with Suspected Acute Coronary Syndromes, Negative Cardiac Biomarkers, and Normal ECGs
Background - Despite uncertain yield, current guidelines endorse routine stress myocardial perfusion imaging (MPI) for patients with suspected acute coronary syndromes, unremarkable serial electrocardiograms, and negative troponin measurements. In these patients, outcome prediction and risk stratification models could spare unnecessary testing. This study therefore investigated the use of artificial neural networks (ANN) to improve risk stratification and prediction of MPI and angiographic results. Methods and Results -We retrospectively identified 5354 consecutive patients referred from the emergency department for rest-stress MPI after serial negative troponins and normal ECGs. Patients were risk stratified according to thrombolysis in myocardial infarction (TIMI) scores, ischemia was defined as >5% reversible perfusion defect, and obstructive coronary artery disease was defined as >50% angiographic obstruction. For ANN, the network architecture employed a systematic method where the number of neurons is changed incrementally, and bootstrapping was performed to evaluate the accuracy of the models. Compared to TIMI scores, ANN models provided improved discriminatory power. With regards to MPI, an ANN model could reduce testing by 59% and maintain a 96% negative predictive value (NPV) for ruling out ischemia. Application of an ANN model could also avoid 73% of invasive coronary angiograms while maintaining a 98% NPV for detecting obstructive CAD. An online calculator for easy clinical use was created using these models. Conclusions - The ANN models improved risk stratification when compared to the TIMI score. Our calculator could also reduce downstream testing while maintaining an excellent NPV, though further study is needed before the calculator can be used clinically.