
| QRS duration >=0.125 sec | Yes No |
| Sinus or supraventricular rhythm present | Yes No |
| Lead V1 with a QS or rS complex | Yes No |
| R wave peak time of >=0.06 sec in I, V5 or V6 associated with the absence of a Q wave in the same lead | Yes No |

Left Bundle Branch Block (LBBB) is most practically diagnosed by the presence of the following on electrocardiogram (EKG):
References: