in a system and method for monitoring cardiac synchrony in a human heart , a first sensor is positioned at a first cardiac wall location that is subject to movements related to longitudinal valve plane movements along the longitudinal axis of the heart , and measures the cardiac wall movements at the first cardiac wall location and a second sensor is positioned at a second cardiac wall location that is subject to movements related to longitudinal valve plane movements along the longitudinal axis of the heart , and measures the cardiac wall movements at the second cardiac wall location . a lead arrangement conducts respective output signals from the first and second sensors to processing circuitry that processes the first and second sensor output signals to produce a synchronization signal therefrom indicative of synchrony in the respective valve plane movements at the first and second cardiac wall locations .