Additional Study Information: The purpose of this study is to collect information about the safety and performance of the investigational leads ACUITY X4 and RELIANCE 4-FRONT. Patients who have been determined to require a Cardiac Resynchronization Therapy Defibrillator (CRT-D) to treat their heart condition will be eligible to be implanted with one or more investigational leads. The device system consists of a CRT-D and at least two or more leads (wires). The CRT-D contains the battery (power source) and the circuitry. The lead is a thin insulated wire that carries electrical impulses from the CRT-D to the heart. The lead also sends electrical signals from the heart to the CRT-D, showing when the heart is beating too fast or too slow and needs treatment. Treatment can consist of either pacing to regulate your heart rate or a shock in order to slow it back down to a normal rate. The CRT-D device is specifically designed for patients with a medical condition called heart failure and helps the heart beat in the way a normal heart would. The leads are placed in different parts of the heart, as needed.