Disclosed herein is a screw-in lead implantable in the pericardium of a patient heart and a system for delivering such leads to an implantation location. The leads include a helical tip electrode and a curvate body including a defibrillator coil with improved contact between the defibrillator coil and the patient heart. The delivery system includes a delivery catheter and lead receiving sheath disposed within the catheter. A fixation tine is disposed on one of the delivery catheter and the lead receiving sheath such that the delivery system may be anchored into the pericardium during fixation of the screw-in lead. In certain implementations, an implantable sleeve receives the leads to bias the defibrillator coil against the patient heart.