Doppler myocardial imaging in patients with heart failure receiving biventricular pacing treatment

Background In patients with heart failure, biventricular pacing (BIV) impro ves left ventricular (LV) performance by counteracting LV unsynchronized co ntraction caused by the presence of left bundle branch block (LBBB). Howeve r, no data are yet available on regional long-axis function in patients wit h LBBB or on BIV effectiveness in improving such a function in patients wit h heart failure and LBBB. Methods and Results We studied with standard 2D echocardiography and tissue Doppler imaging (TDI) 21 nonischemic patients in New York Heart Associatio n (NYHA) class III-IV, with LBBB and QRS greater than or equal to 120 ms, r eceiving BIV. To assess long-axis function, TDI qualitative analysis at the basal level of each LV wall was performed in M-mode color and pulsed wave Doppler modalities before and after BIV. By analysis of the interventricula r septum, the inferior, posterior, lateral, and anterior walls, of 105 basa l segments, the following electromechanical patterns were identified: norma l (pattern I), mildly unsynchronized (pattern IIA), severely unsynchronized (pattern IIB), reversed early in systole (pattern IIIA); reversed late in systole (pattern IIIB), and reversed throughout all the systole (pattern IV ). After BIV, (1) 49 (46.7%) of 105 segments showed unsynchronized contract ion of the same degree as before; (2) 36 (34.3%) of 105 and 20 (19%) of 105 showed unsynchronized contraction of lesser and greater degree, respective ly, than before; and (3) a preexcitation pattern was found in 1 1 (10.5%) o f 105, but no segment with pattern IV was observed. According to TDI analys is, patients were divided into group 1 (10 of 21), with less severe LV asyn chrony than before BIV, and group 2 (11 of 21), with no change or more seve re LV asynchrony than before BIV. In group 1, (1) the LV ejection fraction increased significantly (P = .01); (2) the exercise tolerance, expressed as time and work capacity on the bicycle stress testing, increased significan tly (P = .01, P = .003, respectively); (3) the 6-minute walked distance inc reased significantly (P = .01); and (4) the NYHA class decreased significan tly (P = .003). In group 2, no significant differences were found either in LV ejection fraction, in NYHA class, or in exercise tolerance data (P = no t significant for all). Conversely, the QRS narrowing was significant in bo th groups (P = .003 in group 1 and P = .01 in group 2). Conclusions TDI is useful in assessing the severity of LV asynchrony in pat ients with LBBB with heart failure as well as in evaluating the pacing effe cts on long-axis function in these patients. BIV reduced unsynchronized and /or dyskinetic contraction in at least one third of the LV basal segments, whereas it induced preexcitation in approximately 10%. Such changes were re sponsible for better. LV synchrony in approximately one half of patients. A fter BIV, LV performance improved significantly in patients with better LV synchrony evaluated by TDI, whereas the QRS narrowing was not predictive of this functional improvement.