Benefits of left ventricular endocardial pacing comparing failed implants and prior non-responders to conventional cardiac resynchronization therapy: A subanalysis from the ALSYNC study

Abstract Objective Cardiac resynchronisation therapy (CRT) is limited by a substantial proportion of non-responders. Left ventricular endocardial pacing (LVEP) may offer enhanced possibility to deliver CRT in patients with a failed attempt at implantation and to improve clinical status of CRT non-responders. Methods The ALternate Site Cardiac ResYNChronisation (ALSYNC) study was a prospective, multi-centre cohort study that included 118 CRT patients with a successfully implanted endocardial left ventricular (LV) lead, including 90 failed coronary sinus (CS) implants and 28 prior non-responders who had worsened or unchanged heart failure status after at least 6 months of optimal conventional CRT therapy. Results Patients were followed for 19 ± 9 months. At baseline, prior non-responders were sicker as evidenced by a larger LV end-diastolic diameter (70 ± 12 vs 65 ± 9 mm, p = .03) and a trend towards larger LV end-systolic volume index (LVESVi, 95 ± 51 vs 74 ± 39 ml/m 2 , p = .07), and were more frequently anti-coagulated (96% vs 72%, p = .008) despite similar history of atrial fibrillation (54% vs 51%, p = .83). At 6 months, LVEP significantly improved LV ejection fraction (2.3 ± 7.5 and 8.6 ± 10.0%), New York Heart Association Class (0.4 ± 0.9 and 0.7 ± 0.8), LVESVi (9 ± 16 and 18 ± 43 ml/m 2 ), and six-minute walk test (56 ± 73 and 54 ± 92 m) in prior non-responders and failed CS implants, relative to baseline (all p  Conclusion These data suggest that a sizable proportion of CRT non-responders can improve by LVEP, though to a lesser extent than failed CS implants. Clinical trial registration— URL: http://www.clinicaltrials.gov. Unique identifier: NCT01277783