An implantable cardiac device, comprising: one or more physiological sensors including at least one cardiac sensor configured to detect a ventricular fibrillation or a sudden cardiac death episode of a patient indicating a need for application of a cardiac defibrillation therapy signal; a body orientation unit configured to determine a physical orientation of the patient's body; and characterised in that the device has: alarm circuitry configured to, in response to the at least one cardiac sensor determining that the patient has experienced a ventricular fibrillation or a sudden cardiac death episode, notify the patient that application of a cardiac defibrillation therapy signal is imminent; and cardiac therapy circuitry configured to, after the alarm circuitry has warned the patient that application of the cardiac defibrillation therapy signal is imminent: (i) apply a cardiac defibrillation therapy signal to the patient in response to (a) the at least one cardiac sensor determining that the patient has experienced a ventricular fibrillation or a sudden cardiac death episode, and (b) the body orientation unit determining that the patient is in a substantially horizontal position; and (ii) refrain from applying the cardiac defibrillation therapy signal to the patient in response to (a) the at least one cardiac sensor determining that the patient has experienced a ventricular fibrillation or a sudden cardiac death episode, and (b) the body orientation unit determining that the patient is raising their torso. one or more physiological sensors including at least one cardiac sensor configured to detect a ventricular fibrillation or a sudden cardiac death episode of a patient indicating a need for application of a cardiac defibrillation therapy signal; a body orientation unit configured to determine a physical orientation of the patient's body; and characterised in that the device has: alarm circuitry configured to, in response to the at least one cardiac sensor determining that the patient has experienced a ventricular fibrillation or a sudden cardiac death episode, notify the patient that application of a cardiac defibrillation therapy signal is imminent; and cardiac therapy circuitry configured to, after the alarm circuitry has warned the patient that application of the cardiac defibrillation therapy signal is imminent: (i) apply a cardiac defibrillation therapy signal to the patient in response to (a) the at least one cardiac sensor determining that the patient has experienced a ventricular fibrillation or a sudden cardiac death episode, and (b) the body orientation unit determining that the patient is in a substantially horizontal position; and (ii) refrain from applying the cardiac defibrillation therapy signal to the patient in response to (a) the at least one cardiac sensor determining that the patient has experienced a ventricular fibrillation or a sudden cardiac death episode, and (b) the body orientation unit determining that the patient is raising their torso. alarm circuitry configured to, in response to the at least one cardiac sensor determining that the patient has experienced a ventricular fibrillation or a sudden cardiac death episode, notify the patient that application of a cardiac defibrillation therapy signal is imminent; and cardiac therapy circuitry configured to, after the alarm circuitry has warned the patient that application of the cardiac defibrillation therapy signal is imminent: (i) apply a cardiac defibrillation therapy signal to the patient in response to (a) the at least one cardiac sensor determining that the patient has experienced a ventricular fibrillation or a sudden cardiac death episode, and (b) the body orientation unit determining that the patient is in a substantially horizontal position; and (ii) refrain from applying the cardiac defibrillation therapy signal to the patient in response to (a) the at least one cardiac sensor determining that the patient has experienced a ventricular fibrillation or a sudden cardiac death episode, and (b) the body orientation unit determining that the patient is raising their torso. (i) apply a cardiac defibrillation therapy signal to the patient in response to (a) the at least one cardiac sensor determining that the patient has experienced a ventricular fibrillation or a sudden cardiac death episode, and (b) the body orientation unit determining that the patient is in a substantially horizontal position; and (ii) refrain from applying the cardiac defibrillation therapy signal to the patient in response to (a) the at least one cardiac sensor determining that the patient has experienced a ventricular fibrillation or a sudden cardiac death episode, and (b) the body orientation unit determining that the patient is raising their torso.