Patients from the study group (prospective and retrospective) will be categorized according to the risk score obtained from the multivariate spectral-based model. More specifically, patients will be categorized within four subsets for FNP as follows: very high and high probability of FNP (expected FNP), low and very low probability of FNP (expected non-FNP). Model-derived categorization will be compared with clinical outcomes to assess model sensitivity, specificity and accuracy during hospitalization and follow-up.