Aims: Non-response rate to cardiac resynchronization therapy (CRT) might be decreased by optimizing device programming. The Clinical Evaluation on Advanced Resynchronization (CLEAR) study aimed to assess the effects of CRT with automatically optimized atrioventricular (AV) and interventricular (VV) delays, based on a Peak Endocardial Acceleration (PEA) signal system.
Methods and results: This multicentre, single-blind study randomized patients in a 1 : 1 ratio to CRT optimized either automatically by the PEA-based system, or according to centres' usual practices, mostly by echocardiography. Patients had heart failure (HF) New York Heart Association (NYHA) functional class III/IV, left ventricular ejection fraction (LVEF) <35%, QRS duration >150 or >120 ms with mechanical dyssynchrony. Follow-up was 1 year. The primary endpoint was the proportion of patients who improved their condition at 1 year, based on a composite of all-cause death, HF hospitalizations, NYHA class, and quality of life. In all, 268 patients in sinus rhythm (63% men; mean age: 73.1 ± 9.9 years; mean NYHA: 3.0 ± 0.3; mean LVEF: 27.1 ± 8.1%; and mean QRS duration: 160.1 ± 22.0 ms) were included and 238 patients were randomized, 123 to PEA and 115 to the control group. At 1 year, 76% of patients assigned to PEA were classified as improved, vs. 62% in the control group (P= 0.0285). The percentage of patients with improved NYHA class was significantly (P= 0.0020) higher in the PEA group than in controls. Fatal and non-fatal adverse events were evenly distributed between the groups.
Conclusion: PEA-based optimization of CRT in HF patients significantly increased the proportion of patients who improved with therapy, mainly through improved NYHA class, after 1 year of follow-up.