A sensing and monitoring system configured to measure atrial stretch in a subject based on one or more hemodynamic parameters, the system comprising: one or more sensors (18, 19) configured to generate output signals conveying information related to hemodynamic activity in the subject; and one or more hardware processors configured by machine-readable instructions to: determine the one or more hemodynamic parameters based on the output signals; and determine the atrial stretch in the subject based on the on the one or more determined hemodynamic parameters; wherein the one or more sensors comprise a first sensor and a second sensor wherein the system further comprises a pressure generator that is part of a ventilation support system, the pressure generator being configured to generate a pressurized flow of breathable gas for delivery to an airway of the subject according to a pressure support therapy regime, the pressure support therapy regime indicating pressure levels of the pressurized flow of breathable gas provided by the pressure generator during inhalation and exhalation by the subject; wherein the first sensor is configured to generate output signals conveying information related to venous blood accumulation during cardiac preload in the subject; and the second sensor is configured to generate output signals conveying information related to heart activity and/or systemic arterial circulation in the subject; and wherein the one or more hardware processors are configured to: control the pressure generator to adjust the pressure levels of the pressurized flow of breathable gas during one or both of inhalation and exhalation to facilitate the pulmonary and systemic circulation based on the output signals from the first sensor and the second sensor determine, based on the output signals from the first sensor and the second sensor, whether an episode of atrial fibrillation is occurring or is likely to occur in the subject; and responsive to a determination that atrial fibrillation is occurring or is likely to occur, control the pressure generator to adjust the pressure levels during one or both of inhalation and exhalation to facilitate the pulmonary and systemic circulation, and discourage or prevent the episode of atrial fibrillation. one or more sensors (18, 19) configured to generate output signals conveying information related to hemodynamic activity in the subject; and one or more hardware processors configured by machine-readable instructions to: determine the one or more hemodynamic parameters based on the output signals; and determine the atrial stretch in the subject based on the on the one or more determined hemodynamic parameters; determine the one or more hemodynamic parameters based on the output signals; and determine the atrial stretch in the subject based on the on the one or more determined hemodynamic parameters; wherein the one or more sensors comprise a first sensor and a second sensor wherein the system further comprises a pressure generator that is part of a ventilation support system, the pressure generator being configured to generate a pressurized flow of breathable gas for delivery to an airway of the subject according to a pressure support therapy regime, the pressure support therapy regime indicating pressure levels of the pressurized flow of breathable gas provided by the pressure generator during inhalation and exhalation by the subject; wherein the first sensor is configured to generate output signals conveying information related to venous blood accumulation during cardiac preload in the subject; and the second sensor is configured to generate output signals conveying information related to heart activity and/or systemic arterial circulation in the subject; and wherein the one or more hardware processors are configured to: control the pressure generator to adjust the pressure levels of the pressurized flow of breathable gas during one or both of inhalation and exhalation to facilitate the pulmonary and systemic circulation based on the output signals from the first sensor and the second sensor determine, based on the output signals from the first sensor and the second sensor, whether an episode of atrial fibrillation is occurring or is likely to occur in the subject; and responsive to a determination that atrial fibrillation is occurring or is likely to occur, control the pressure generator to adjust the pressure levels during one or both of inhalation and exhalation to facilitate the pulmonary and systemic circulation, and discourage or prevent the episode of atrial fibrillation. control the pressure generator to adjust the pressure levels of the pressurized flow of breathable gas during one or both of inhalation and exhalation to facilitate the pulmonary and systemic circulation based on the output signals from the first sensor and the second sensor determine, based on the output signals from the first sensor and the second sensor, whether an episode of atrial fibrillation is occurring or is likely to occur in the subject; and responsive to a determination that atrial fibrillation is occurring or is likely to occur, control the pressure generator to adjust the pressure levels during one or both of inhalation and exhalation to facilitate the pulmonary and systemic circulation, and discourage or prevent the episode of atrial fibrillation.