Provided herein are implantable systems, and methods for use therewith, for monitoring a patient's arterial blood pressure while a patient's heart is being paced. A signal (e.g., PPG or IPG signal) indicative of changes in arterial blood volume remote from the patient's heart is obtained using a sensor or electrodes that are implanted remote from the patient's heart. One or more metrics indicative of pulse arrival time (PAT) are determined, where each metric can be determined by determining a time from a paced cardiac event to one or more predetermined features of the signal indicative of changes in arterial blood volume. Based on at the metric(s) indicative of PAT, arterial blood pressure is estimated, which can include determining values indicative of systolic blood pressure, diastolic blood pressure, pulse pressure and/or mean arterial blood pressure, and/or changes in such values.