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; 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 complete left bundle branch block 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 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 < .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 a smaller reduction in the lateral-septal wall MW difference. MW difference in lateral-septal wall and basal septum thinning were determinants for the left ventricular end-systolic volume 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.