Efficacy of Cardiac Resynchronization Therapy on Cardiac Sarcoidosis: Insight into Mechanism of Mechanical Response and the Role of Myocardial Work.

Background: Cardiac resynchronization therapy (CRT) improves the prognosis of patients with heart failure and complete left bundle branch block (CLBBB); however, its efficacy in cardiac sarcoidosis (CS) remains unclear.

Objective: This study evaluated the mechanisms of CRT response in patients with and without CS, focusing on myocardial work (MW) assessment.

Methods: Twenty and 73 patients with CS and dilated cardiomyopathy (DCM) who underwent CRT implantation and had CLBBB and QRS width of ≥150 ms were assessed. Two-dimensional speckle-tracking echocardiography was performed before implantation, and 1 week and 6 months after implantation. MW was estimated by pressure-strain analysis using echocardiography. Responders were defined as ≥15% decrease in left ventricular end-systolic volume (LVESV) after 6 months. The outcomes and changes in MW were compared between the groups.

Results: The CS group exhibited a lower response rate (40% vs. 84%, p<0.001) and a higher incidence of death and left ventricular assist device implantation than the DCM group. The CS group had a higher MW of the septal wall and smaller MW differences in the lateral-septal wall before implantation than the DCM group. After implantation, the increase in the septal wall MW was significantly lower in the CS group, resulting in smaller reduction in the lateral-septal wall MW difference. MW difference in lateral-septal wall and basal septum thinning were determinants for the LVESV reduction.

Conclusion: Patients with CS had poor outcomes after CRT. Baseline MW differences in the lateral-septal wall and improvements in septal MW may play an essential role in improving cardiac function.