Abstract
BACKGROUND:
"Nonresponse" to cardiac resynchronization therapy (CRT) is recognized, but definition(s) applied in practice, treatment(s), and their consequences are little known.
OBJECTIVES:
The authors sought to assess nonresponse in the prospective, international, ADVANCE CRT registry (Advance Cardiac Resynchronization Therapy Registry).
METHODS:
Each subject's response was assessed at 6 months post-implantation using site-specific definitions and compared with the independently derived clinical composite score (CCS). Treatment(s) and hospitalization(s) were tracked during the following 6 months.
RESULTS:
Of 1,524 subjects enrolled in 69 centers (68 ± 12 years of age, 32% female, ischemic disease 39%), 74.3% received CRT-defibrillator devices, using mainly quadripolar LV leads (75%) deployed laterally (78%). Indications for CRT were wider than past trials. Among 1,327 evaluable subjects, site-defined nonresponse was 20.0% (greater age, comorbidities, ischemic cardiomyopathy, non-left bundle branch block, and lower %CRT pacing vs. responders). Site definitions used mainly clinical criteria (echocardiography infrequently), and underestimated nonresponders by 35% compared with CCS (58% sensitivity vs. CCS). Overall, more site-defined nonresponders received treatment (55.9% vs. 38.3% of responders; p < 0.001) using medication changes and heart failure education, but device programming less frequently. Intensification of in-clinic/remote evaluations and involvement of heart failure specialists remained minimal. Remarkably, 44% of site-defined nonresponders received no additional treatment. Frequency and duration of hospitalizations, and death, among site-defined nonresponders was significantly higher than responders.
CONCLUSIONS:
A high incidence of CRT nonresponders persists despite good patient selection and LV lead position, but site identification methods have modest sensitivity. Following diagnosis, nonresponders are often passively managed, without specialty care, with poor outcome. ADVANCE CRT exposes a vulnerable group of heart failure patients. (Advance Cardiac Resynchronization Therapy Registry [ADVANCE CRT]; NCT01805154).
Varma, Niraj