Early Cardiac Resynchronization Therapy (CRT) may slow the progression of heart failure in patients with mild to moderately reduced left ventricular ejection fraction (LVEF) and left bundle branch block (LBBB), according to a study conducted by a research team led by Yong-Mei Cha, MD, cardiac electrophysiologist at Mayo Clinic, Rochester, MN, which was sponsored by the National Heart, Lung, and Blood Institute. The findings were presented during the final day of the Heart Rhythm Society meeting, HRS 2024. Image courtesy: Mayo Clinic
May 19, 2024 — A physician-initiated prospective, randomized clinical trial sponsored by the National Heart, Lung, and Blood Institute (NHLBI) found that early cardiac resynchronization therapy (CRT) may slow the progression of heart failure in patients with mild to moderately reduced left ventricular ejection fraction (LVEF) and left bundle branch block (LBBB). Researchers presented these findings “Late Breaking Clinical Trials and Science – CIEDs: Early Cardiac Resynchronization Therapy for Patients with Moderately Reduced Ejection Fraction and Left Bundle Branch Block” this morning during the May 16-19 meeting of the Heart Rhythm Society, HRS 2024, being held in Boston, MA.
Approximately 6.7 million adults in the U.S. have heart failure, and the prevalence is expected to rise to 8.5 million by 2030.1 Additionally, more than 30% of heart failure patients have conduction abnormalities. CRT, a pacemaker that corrects abnormal electrical conduction by simultaneously pacing the left and right heart chambers, is a well-established therapy for improving cardiac efficiency. According to the 2023 HRS guidelines on cardiac physiologic pacing, CRT can lead to improvement in survival time, decline in hospitalizations for heart failure, and stabilization of ventricular function.
“In this study, we proposed use of CRT for patients to prevent the progression of mild to moderate heart failure,” said Yong-Mei Cha, MD, cardiac electrophysiologist at Mayo Clinic, Rochester, MN. Cha added, “We confirmed early CRT improves cardiac systolic function in these patients, which supports HRS guidelines.”
To assess if CRT would improve or halt the progression of heart failure in patients with mild to moderately reduced LVEF and LBBB, Mayo Clinic researchers randomized clinical trial participants to receive either CRT-off (VVI RV pacing 40bpm) or CRT-on (DDDR BIV pacing 60-150bpm). After 6 months, the programming was reversed for another 6 months: patients who originally received CRT-off received CRT-on, and patients who originally received CRT-on received CRT-off.
Patients who received CRT-off first experienced a significant reduction in left ventricular end-systolic volume (LVESV) only after the later CRT-on phase. Similarly, patients who received CRT-on first, followed by CRT-off, showed significant LVESV reduction in the initial CRT-on phase. Because LVESV remained lower than baseline even after the 12-month trial period, researchers concluded that the effects of CRT may persist for up to 6 months after CRT was turned off, indicating a CRT carry-over effect.
Looking ahead, the Mayo Clinic research team will investigate the long-term clinical outcomes of CRT in patients with mild to moderately reduced LVEF and LBBB, further advancing the understanding of this treatment option.
More information: www.HeartRhythm.com
Reference:
1 Bozkurt B, Ahmad T, Alexander KM, Baker WL, Bosak K, Breathett K, Fonarow GC, Heidenreich P, Ho JE, Hsich E. Heart failure epidemiology and outcomes statistics: a report of the Heart Failure Society of America. Journal of cardiac failure. 2023 Oct;29(10):1412.
June 08, 2023 
