Usefulness of left ventricle dyssynchrony assessment before cardiac resynchronization implantation

A number of trials have demonstrated the effect of cardiac resynchronization therapy (CRT) on functional improvement and reversed left ventricle remodeling. Meeting contemporary guidelines approximately 30- 40% of patients do not respond to CRT (non-responders).

To quantify the predictive ability of basal QRS width and basal echocardiographic parameters of left ventricle contraction dyssynchrony in our group of CRT patients. To compare effectiveness of these parameters assessment in patients with ischemic (iCMP) and non-ischemic cardiomyopathy (niCMP) and with sinus rhythm (SR) and atrial fibrillation (AF).

194 patients after successful introduction of CRT device were evaluated. Evaluation of NYHA function class, QRS width and echocardiographic parameters including parameters of left ventricle contraction dyssynchrony (SPWMD: septal-to-posterior wall motion delay, Ts-sep-lat: time interval between maximum of systolic movement of septum and lateral wall using tissue Doppler imaging, IVMD: interventricular mechanical delay) performed before implantation and 3 months after implantation of CRT device.

Responder (improved in NYHA class after CRT) rate was 61%. SR patients showed higher benefit compared to AF patients (responder rate 63% vs. 52%, p<0.05). Narrowing of QRS width after CRT was observed only in responders. SPWMD and Ts-sep-lat decreased after CRT in all subgroups. SPWMD dyssynchrony (SPMWD > or = 130 ms) reduction after CRT was more expressed in niCMP population. Ts-sep-lat dyssynchrony (Ts-sep-lat > or = 65 ms) reduction after CRT was more expressed in SR patients. IVMD (IVMD > or = 60 ms) remained unchanged in average, but significant decrease was observed in responders and significant increase in non-responders. QRS width, SPWMD and Ts-sep-lat showed moderate sensitivity but poor specificity to predict CRT benefit. QRS width > or = 150 ms in niCMP patients showed higher sensitivity to predict CRT effect compared to iCMP patients (91%, 65% respectively). IVMD showed poor sensitivity but good specificity to predict CRT benefit. IVMD in SR patients (compared to AF patients) showed higher specificity to predict CRT effect (90%, 63% respectively).

None of tested left ventricle contraction dyssynchrony parameters showed good sensitivity and specificity to predict CRT benefit. QRS width as a predictor factor was more beneficial in non-ischemic patients and IVMD in sinus rhythm patients.