Specificity of electrocardiographic criteria for the differential diagnosis of wide QRS complex tachycardia in patients with intraventricular conduction defect

Background In patients with organic intraventricular conduction defects (IVCDs), (1) QRS morphology during sinus rhythm frequently meets ventricular tachycardia (VT) morphological criteria and (2) there are further rate-related changes in QRS morphology. Objective To search for the best morphological criteria in this context. Methods We prospectively studied 69 patients, in sinus rhythm, with QRS duration ≥120 ms. Continuous rapid atrial pacing (RAP) trains were introduced at increasing rates in order to mimic supraventricular tachycardia. We analyzed the specificity of VT criteria during RAP. Finally, we used the criteria with a specificity of ≥0.9 in a "test sample" of 53 patients with preexisting IVCD and wide complex tachycardia to confirm their validity. Results Only 10 of the 20 analyzed criteria had a specificity of ≥0.9 during RAP at the highest rate. The specificity of these 10 criteria was confirmed in the test sample. The best accuracy to diagnose VT was obtained: for an isolated criterion: "R-wave peak time (RWPT) ≥50 ms at lead II" (specificity = 0.97; sensitivity=0.67); for an algorithm: the combination of 2 criteria "RWPT ≥50 ms at lead II" and "absence of RS patterns in precordial leads" (specificity = 0.97; sensitivity=0.88). Conclusions In patients with IVCD, (1) specificity of most VT criteria is low during RAP, suggesting a limited applicability of many of these criteria in case they develop supraventricular tachycardia, and (2) the superior accuracy to diagnose VT was observed with "RWPT ≥50 ms at lead II" and for an algorithm with the combination of "RWPT ≥50 ms at lead II" and "absence of RS patterns in precordial leads."