Approximately 40% of patients with heart failure who are eligible for cardiac resynchronization therapy (CRT) do not respond to treatment or are unable to receive it due to anatomic obstacles.[1] Conventional pacing through the coronary sinus is nonphysiological because the electrical wavefront propagates from the epicardium to the endocardium, contrary to normal cardiac activation.[1] The WiSE CRT system represents a new lead-free left ventricular endocardial stimulation using ultrasound energy.[1] The system consists of a battery with an ultrasound transmitter implanted subcutaneously and a receiver in the endocardium of the left ventricle, which requires cooperation with a right ventricular pacemaker.[1] The transmitter records the stimulation of the right ventricle and sends an ultrasound pulse within 5 milliseconds, which is converted into electrical energy for stimulation of the left ventricle.[1] 55% of participants improved their NYHA class, 41% remained unchanged, and 3.4% worsened by one class.[1] The length of the paced QRS was shortened by an average of 39.3 milliseconds (SD 23.3).[1] This lead-free system is a promising alternative for patients with failed coronary sinus lead implantation.[1]