Abstract
Cardiac resynchronization therapy (CRT) is an established treatment option for heart failure patients. However, up to 20% of CRT candidates are non-responders due to suboptimal pacing sites. An endocardial wireless technology based on energy transmission by ultrasound through the intercostal space can be used for leadless LV cardiac stimulation. In combination with a co-implanted leadless RV pacemaker, CRT can be achieved. We implanted a totally leadless pacemaker system (Micra VR TCP, Medtronic and Wireless Stimulation Endocardially for CRT, WiSE-CRT, EBR Systems Inc.) in two patients. In this report we report the follow-up until 1 year after implantation. N/A Patient #1 was an 82-year old man with ischemic cardiomyopathy and permanent atrial fibrillation who developed a broad left bundle branch block after TAVR. To avoid worsening of the preexisting tricuspid regurgitation, we decided to implant a totally leadless CRT device. Patient #2 (male, 77 years) with dilated cardiomyopathy and persistent bradyarrhythmia had a CRT system explanted due to previous pocket infection. This led to the decision to re-implant a leadless CRT system. Immediately after the WISE-CRT system was activated, biventricular pacing showed narrowing of the QRS width (pat. #1: 170 ms to 130 ms, pat. #2: 145 ms to 120 ms). During one year follow-up in patient #1, LV-EF improved from 20 % to 40 %. The degree of MR and TR improved from °III to °I-II. Dyspnea improved from NYHA class IV to II. NT-proBNP levels also decreased from 2440 to 1118 pg/ml. The CRT system showed a LV-RV tracking rate of 96-97 %. In patient #2 the LV-EF remained stable at 30 %. The degree of MR and TR were moderate and unchanged to baseline. The patient was hospitalized twice due to congestive heart failure. CRT controls showed a LV-RV tracking rate of 95-98 %. Transmit levels (TL, corresponds to pacing threshold) were significantly higher in patient #2 than in patient #1 indicating intermittent non capture in patient #2 (pat. #1: TL 3/0.5 to 2/0.3 ms, pat. #2: TL 6/0.8 to 6/1.5 ms). We found implantation of a totally leadless CRT-P system feasible and safe in two patients. Like in conventional CRT, the rate of biventricular pacing is crucial for the effect of resynchronization.
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