Correlation of electrocardiographic criteria for left bundle branch block with intraventricular synchrony

Abstract

Abstract Funding Acknowledgements Type of funding sources: None. INTRODUCTION About 30% of patients are nonresponders to cardiac resynchronization therapy. One of the reasons proposed is that these patients do not present a true left bundle branch block (LBBB) and for that reason they do not develop dyssynchrony in the left ventricle. New electrocardiographic criteria have been published to define a true LBBB. Synchromax is a non-invasive, simple and practical method that has been shown to have a high predictive value for detecting electrical dyssynchrony and a very good correlation with mechanical dyssynchrony. OBJECTIVE Correlate the electrocardiographic criteria of LBBB individually or grouped, with the presence of dyssynchrony. METHODOLOGY Patients with LBBB (Minnesota Code) were prospectively collected. Those with pacemakers were excluded. The following electrocardiographic criteria were analyzed individually and in association: a) QS image in V1; b) QRS duration: 120-149 ms, ≥150 ms; c) Monophasic complexes with Notching or Slurring in D1 and / or V6 (Notch / S); d) QRS axis in the frontal plane deviated to the left (≥ -30º). Synchromax curves and values were taken from all patients and classified according to the indices as Synchronous (<0.4), Intermediate (0.4-0.7) or Asynchronous (> 0.7). RESULTS Were included 46p; age 34-89 years; 27 men. Heart rhythm was sinus in 40p and atrial fibrillation in 6p. The underlying heart disease was: Ischemic: 20p, Dilated Cardiomyopathy: 4p, Valvular: 3p, Chagas: 1p, Hypertensive heart disease: 18p. The results can be seen in table 1. CONCLUSION Of the LBBB electrocardiographic criteria analyzed in this study, QRS duration ≥150 ms and left axis deviation were the best predictors of dyssynchrony individually and in association. Table 1: ResultsQRS120/149QRS ≥150QSV1Notch/SLeftAxisQSV1+≥150Notch/S+≥150LeftAxis+≥150Nº Patients2917272625131110Synchronous5(17%)2(16%)3(11%)5(19%)1 (4%)2(15%)1(9%)0Intermediate6(20%)1(8%)4(15%)2(7%)2(8%)1(8%)1(9%)0Asynchronous18(63%)14(82%)20(74%)19(74%)22(88%)10(77%)9(82%)10(100%)Abstract Figure. synchronous and asynchronous LBBB