Comparison of the Electrocardiographic Features of Complete Left Bundle Branch Block in Patients with Ischemic and Nonischemic Left Ventricular Dysfunction

BACKGROUND: Differentiating ischemic (ILVD) from nonischemic left ventricular dysfunction (NILVD) is important prognostically and therapeutically but might be difficult clinically. The differentiating role of electrocardiographic (ECG) features in the presence of left bundle-branch block (LBBB) is debatable on differentiating ILVD from NILVD. OBJECTIVE: The present study assessed whether there is the role of certain ECG features in differentiating ILVD from NILVD in the presence of the complete LBBB. METHODS AND RESULTS: Patients who had LBBB were divided into two groups based on the presence and type of left ventricular dysfunction; (1) ILVD group (49 patients; 20 female; age: 65 ± 11 years) and (2) NILVD group (49 patients; 22 female; age: 59 ± 12 years), and numerous ECG features were compared. Most of these ECG features did not show any difference between the groups except for following ECG findings; the voltage of R wave in V6 were statistically higher in NILVD group compared ILVD group (p: 0.03); the depression of the ST-J point by more than 0.2 mV in V6 were also frequently observed in NILVD group compared ILVD group (5/ 10% vs 19/ 39% , p: 0.001); and the notching in the ascending or descending limb of the S wave in V1-4 leads were more in ILVD group (18/ 36% vs 8/ 16% p: 0.03; 9/ 16% vs 2/ 4%, p: 0.03, respectively). CONCLUSION: In the current study, although some ECG findings were found to be useful, ECG features in the presence of complete LBBB had poor value in differentiating ILVD from NILVD.