Lead positioning for cardiac resynchronization therapy: techniques and priorities

Although cardiac resynchronization therapy (CRT) has demonstrated to be an effective treatment for heart failure patients, up to 30-40% of the patients do not show a favourable response. Implantation of the left ventricular (LV) pacing lead is one of the determinants of CRT response. This procedure includes several challenging technical issues and strongly depends on the highly variable anatomy of the coronary sinus and tributaries. In addition, the final position of the LV pacing lead may target the latest activated areas of the left ventricle in order to obtain effective resynchronization. Furthermore, the presence of transmural myocardial scar at the region targeted by the LV lead may also determine the response to CRT. This review discusses all the issues related to LV lead implantation and the role of multimodality imaging to anticipate the implantation strategy. Finally, alternative LV pacing sites and their effect on clinical outcome and LV performance will be discussed.