Abstract
Although cardiac resynchronization therapy (CRT) has been proven to improve morbidity and mortality, the rate of non‐response is still high, occurring in up to 30% of patients. Besides known patient characteristics (type of intraventricular conduction delay, amount of scarring, comorbidities), several issues may be encountered during the implantation which may affect the long‐term efficacy of CRT including unfavorable coronary venous anatomy, high pacing threshold, and phrenic nerve stimulation. Optimal hardware selection, implant technique, and device programming is crucial to achieve the best clinical response. Occasionally, conventional transvenous CRT implantation is not feasible and use of interventional or surgical techniques may be necessary to achieve optimal outcome.