Evaluation of ventricular dyssynchrony in patients with systolic CHF prior to implantation of devices for cardiac resynchronization therapy
<i>Background</i>. Asynchronous myocardial contractions adversely affect the LV pump function by increasing the volume and degree of mitral regurgitation, which is associated with unfavorable prognosis. However cardiac resynchronization therapy (CRT) is effective only in 60-80 % of patients with disturbed intraventricular conduction, which justifies a further search for CRT treatment criteria. <i>Aim</i>. To evaluate the effect of transesophageal electric stimulation of the heart (stress agent) on ventricular dyssynchrony in patients with impaired LV systolic function scheduled for CRT. <i>Materials and methods</i>. The study included 61 subjects: 37 patients with drug-compensated CHF and 24 healthy volunteers (control group) with normal ECG and results of stress test. Mean age of CHF patients was 54.3±10.1 years. Inclusion criteria for CHF patients were sinus rhythm and LV systolic dysfunction with LV EF <35 %. Patients had NYHA FC II (n=17) or III (n-25) CHF. 24 patients had CHF of ischemic origin and 13 patients had CHF of non-ischemic origin. Stress EchoCG was performed using transesophageal stimulation of the heart as a stress agent. <i>Results</i>. Depending on the measured parameter, the proportion of patients with dyssynchrony at rest ranged from 52 to 66 % for the entire group, from 32 to 50 % for the subgroup with QRS<120 ms, and from 63 to 74 % in the subgroup with QRS>120 ms. The SD value of 12 was the most representative index of dyssynchrony in these patients. From 55 to 69 % of patients had dyssynchrony during exercise. From 32 to 45 % of them were patients with QRS<120 ms and from 67 to 81 % were patients with QRS>120 ms. The linear regression analysis for the velocity-time integral (VTI) of the LV outflow tract and dyssynchrony parameters showed a considerable inverse correlation of changes at rest and cardiac ejection load with Ts <sub>max</sub>- Ts <sub>min</sub> (r = -0.65; p<0.01), TO-6base (r = -0.68; p<0.01), SD-12 (r = -0.63; p<0.01) and SPWMD (r = -0.54; p<0.05). <i>Conclusion</i>. In selection of patients for CRT, stress-EchoCG detected latent dyssynchrony in 80 % of cases. Based on evaluation of stress-EchoCG data, an algorithm was developed for selection of patients for CRT. The number of LV viable segments found by EchoCG may determine the response to CRT in IHD patients, which requires further study.