Transient drop in the heart beat or transient heart block (AVB) may be consider the main cause of syncope or presyncope inpatients with bifascicular block and syncope According to the Guidelines for cardiac pacing pacemaker consider part of treatment. Aims of our study were to evaluate whether there is role for EPS in patients BFB and to evaluate the symptoms after pacing. 42 patients were enrolled in this study, with mean age value (63.4± 12.2years), suffer from interventricular conductive defect and syncope; patients underwent EPS on admission time, and pacemaker implantation accordingly and programmed follow up for the device in the last four years. Our patients were 25 (59.5%) male and 17 (40.5%)female, all of them with syncope or presncope and good left ventricular systolic function and the left ventricular ejection fraction (LVEF ≥55%). Left bundle branch block was found in 28 (66.71%) patients, while right bundle branch block were found in,14 (33.3) of them, the result of the EPS was find the cut of HV interval for pacing which represent that that the threshold at level of 75 have a sensitivity of 91% and specificity of 80%. The greater HV intervals gave more successful results for pacing. Pacemaker was implanted in 27 (64.3%) of the patients, with significant relation between pacing and syncope disappeared after pacemaker implantation (p value 000) and in 15 (35.7%) no pacemaker was implanted with persistent symptoms. Pacing were more between patients with coronary artery disease and LBBB with abnormal EPS finding. Permanent pacemaker implantation can implant directly in those old patients with syncope and bifascicular block that associated with LBBB and coronaries artery diseases without or before EP study
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