ABSENCE OF CORRELATION BETWEEN QRS DURATION AND ECHOGRAPHIC PARAMETERS OF VENTRICULAR DESYNCHRONIZATION. CAN WE STILL TRUST THE ELECTROCARDIOGRAPHIC CRITERIA?

Abstract

Background: Identification of the responder candidates for multisite pacing is still difficult and severe heart failure, dilated left ventricle with reduced ejection fraction, prolonged QRS with left bundle branch block (LBBB) are still considered the principal indicators of ventricular desynchronization. The aim of the study was to assess if echographic ventricular desynchronization parameters measured in patients with dilated cardiomyopathy and severe heart failure are correlated with the duration of the QRS on surface electrocardiogram. Methods: This study included 51 patients aged 58.8 ± 7.4 years with idiopathic DCM. The following parameters were measured: QRS duration; effective contraction time (ECT) measured as the interval between QRS onset and closure of aortic valve, interventricular delay (IVD) measured as the time between onset of aortic and pulmonary flow, left ventricular mechanical delay (LVD) as the time from maximal interventricular septum contraction and posterior wall contraction, posterior (P), lateral (L), and posterolateral (PL) wall delays, as the time from QRS onset to maximal wall contraction. Regional post‐systolic contraction was defined in a given wall as the difference (contraction delay − ECT)> 50 ms. Results: 29 patients presented complete LBBB, 22 patients had QRS duration < 120 ms. 39 patients had a post‐systolic contraction of the PL wall (32 patients of the L wall and 26 patients of the P wall). 16 patients with QRS duration <120 had a post‐systolic contraction of the PL wall (as for the LBBB the rest of 39 patients). In 40 patients the sequence of regional ventricular contraction was: P‐L‐PL wall (16 patients with QRS < 120). LVD was > 100 ms in 36 patients (26 patients with LBBB and 10 with QRS < 120). 27 patients with LBBB and 6 with QRS < 120 ms presented IVD > 30 ms. There was no correlation between the QRS duration and the parameters listed above. Conclusions: In a population of patients with severe heart failure and dilated cardiomyopathy there is no correlation between the duration of the QRS and echocardiographic parameters of ventricular desynchronization. These results show that mechanical ventricular desynchronization can be observed in patients with a QRS duration < 120 ms. Further studies are needed to evaluate if this population could beneficiate of multisite pacing therapy.