Troubleshooting Cardiac Resynchronization Therapy in Nonresponders

Heart failure (HF) is a critical health issue. Despite the advancements in pharmacotherapy, HF-related morbidity and mortality remains high. Cardiac resynchronization therapy (CRT) has been revolutionary in medically refractory, symptomatic HF patients with reduced ejection fraction and a prolonged, abnormal QRS complex. Although CRT affects electromechanical dys-synchrony resulting in favourable ventricular remodelling, improved functional capacity and clinical outcomes with fewer HF hospitalizations and better survival, the response to CRT is not uniform. A reported 20%-40% of patients, depending on the criteria used, are considered CRT nonresponders. Identifying a cause for nonresponse is challenging and often multifactorial and therefore requires a complete approach involving the entire patient journey. Effort to improve response includes careful consideration of selected patients, optimal therapy delivery, and comprehensive postimplantation care. Because of the prevalence of HF and generally poor prognosis, CRT provides an important treatment option, however, further research is needed to better understand reasons for CRT nonresponse and potential solutions.