Evaluation of the specificity of morphological electrocardiographic criteria for the differential diagnosis of wide QRS complex tachycardia in patients with intraventricular conduction defects.

Abstract

Although several ECG criteria have been described for the differential diagnosis of tachycardias with a wide QRS complex, their applicability in patients with preexisting intraventricular conduction defects (IVCDs) has been questioned. The specificity of previously described criteria in this context is unknown. We analyzed prospectively the specificity of the QRS morphological criteria previously described in ECGs during sinus rhythm of 232 patients with IVCD. Only 5 of 12 analyzed criteria had a specificity > or = 0.90 among our patients: (1) a triphasic configuration (Rsr' or Rr') QRS complex in V1 in the presence of a right bundle-branch block morphology (BBBM); (2) a QS, QR, or R QRS pattern in V6 in the presence of a right BBBM; (3) any Q in V6 in the presence of a left BBBM; (4) a concordant pattern in all precordial leads; and (5) the absence of an RS complex in all precordial leads (particularly useful for left BBBM). The following criteria--QRS duration > 140 ms; a left axis with right BBBM, right superior axis with right BBBM, monophasic or biphasic R wave in V1 with right BBBM, and a relation R/S < 1 with right BBBM; an R > 30 ms in lead V1 or V2 with left BBBM, > 60 ms from QRS onset to S nadir with left BBBM, a notched downstroke S wave with left BBBM, and an R-to-S interval > 100 ms in one precordial lead--had a specificity of 0.43, 0.54, 0.87, 0.80, 0.85, 0.78, 0.66, 0.69, and 0.63 (0.84 in right BBBM), respectively. Most of the previously described morphological criteria favoring ventricular tachycardia are present in a substantial percentage of patients with IVCD during sinus rhythm. These findings suggest a limited applicability of these criteria in this subset of patients.