1. A system for determining cardiovascular information for a patient, the system comprising: at least one computer system configured to: receive patient-specific data of the patient's cardiovascular anatomy; obtain a first model representing a portion of the patient's cardiovascular anatomy based on the patient-specific data; determine a first point of interest in the first model; determine, for the first point of interest, a first mean blood flow rate within the patient's cardiovascular anatomy represented by the first model; identify one or more narrowings of vasculature upstream from the first point of interest; determine, for each identified narrowing upstream from the first point of interest, a modified cardiovascular anatomy based on a potential treatment or mitigation of each narrowing; generate a revised model by modifying the first model based on the determined modified cardiovascular anatomy; determine a revised model point of the revised model corresponding to the first point of interest of the first model; determine, for the revised model point, a second mean blood flow rate within the patient's cardiovascular anatomy represented by the revised model; and determine and generate an output of a ratio of the second mean blood flow rate of the revised model to the first mean blood flow rate of the first model.