The Use of Different Methods for the Selection of Patients with Non-Ischemic Cardiomyopathy for Cardiac Resynchronization Therapy

Aim: The aim of the study was to use various methods of selection of patients for cardiac resynchronization therapy (CRT) and to evaluate prospects of method implementation in clinical practice to increase treatment efficacy.

Materials and Methods: The study comprised a total of 180 patients aged 32 to 75 years (55±12years) with dilated cardiomyopathy (DCM), NYHA functional class III heart failure, left ventricular (LV) ejection fraction (EF) of 30.1±3.8%, 6-min walk test distance of 290.5±64.3 m, end diastolic volume (EDV) of 220.7±50.9 mL, intraventricular and interventricular dyssynchrony of >120 ms. At the selection stage, patients were divided into three groups: group 1 (n=50) that received assessment of myocardial metabolism defect (MMD) by radionuclide methods, group 2 (n=70) that received assessment of tricuspid annular systolic velocity (TASV), and control group.

Results: One-year follow-up study showed that 141 patients (78.3%) clinically responded to CRT; 39 patients (21.7%) did not respond to CRT. Evaluation of the selection methods demonstrated that 6 (12%), 17 (24,3%), and 20 (33,3%) patients did not respond to CRT in group 1, 2, and 3, respectivley. Group 1 included 44 responders (88%) whose MMD was <15% prior to CRT; if initial MMD was >15%, patients did not respond to CRT. Group 2 included 53 responders (75,7 %) whose TASV was >10 cm/s (12.5±2.1 cm/s) (р=0.0001).

Conclusions: (1) Preserved myocardial metabolism (LV MMD <15%) is a predictor of efficacious CRT in DCM patients. (2) Tricuspid annular systolic velocity is an independent predictor of response to CRT; TASV enables to identify CRT responders with sensitivity of 85% and specificity of 83% at the selection stage. (3) For selection of patients for CRT, the administration of all presented methods is rational in order to increase treatment efficacy.