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| Type of tachycardia | QRS width, ms | QRS pattern | QRS axis |
| Posterior fascicle (most frequent) | < 120–140 | RBBB | Left |
| Anterior fascicle | < 120–140 | RBBB | Right |
| Upper septal fascicle | 120 | RBBB or normal | Normal |
With modifications from Kapa, et al.[24] RBBB: right bundle branch block.
