Application and Research of Left Bundle Branch-Optimized Cardiac Resynchronization Therapy in Ischemic Cardiomyopathy

BACKGROUND: This study aimed to evaluate the effectiveness of left bundle branch-optimized cardiac resynchronization therapy (LOT-CRT) in patients diagnosed with heart failure and reduced ejection fraction due to ischemic cardiomyopathy.

METHODS: A total of 78 patients with ischemic cardiomyopathy who underwent pacemaker implantation at a single center between March 2020 and March 2022 were randomly assigned to two groups based on different pacing methods: LOT-CRT group (n = 39) and biventricular pacing (BVP) group (n = 35). Pacing threshold, impedance, electrocardiogram QRS wave duration during pacing, ventricular pacing ratio during follow-up, and cardiac ultrasound-related indicators were compared immediately after surgery and at the six-month follow-up.

RESULTS: The two groups were similar regarding baseline characteristics, cardiac ultrasound and magnetic resonance imaging (MRI) parameters, and overall cardiac function. However, the BVP group demonstrated higher pacing thresholds and impedance levels immediately after surgery and at the six-month follow-up (p < 0.001). Moreover, the X-ray exposure time was significantly longer in the BVP group compared to the LOT-CRT group. While no significant differences in QRS duration were observed between the groups preoperatively, the QRS duration in the LOT-CRT group was significantly shorter both immediately after surgery and during follow-up (p < 0.001). No significant differences were found between the groups in terms of the New York Heart Association (NYHA) functional class, left ventricular ejection fraction (LVEF), or left ventricular end-diastolic diameter (LVEDD). Six months post-surgery, both groups showed modest improvements in NYHA class, LVEF, and LVEDD, with the LOT-CRT group demonstrating significant improvements (p < 0.001).

CONCLUSIONS: LOT-CRT may be an alternative treatment for patients with heart failure complicated by left bundle branch block due to ischemic cardiomyopathy in whom BVP is ineffective.