A new approach to the differential diagnosis of a regular tachycardia with a wide QRS complex.

BACKGROUND: In the differential diagnosis of a tachycardia with a wide QRS complex (greater than or equal to 0.12 second) diagnostic mistakes are frequent. Therefore, we investigated the reasons for failure of presently available criteria, and we identified new, simpler criteria and incorporated them in a stepwise approach that provides better sensitivity and specificity for making a correct diagnosis.

METHODS AND RESULTS: A prospective analysis revealed that current criteria had a poor specificity for the differential diagnosis. The value of four new criteria incorporated in a stepwise approach was prospectively analyzed in a total of 554 tachycardias with a widened QRS complex (384 ventricular and 170 supraventricular). The sensitivity of the four consecutive steps was 0.987, and the specificity was 0.965.

CONCLUSIONS: Current criteria for the differential diagnosis between supraventricular tachycardia with aberrant conduction and ventricular tachycardia are frequently absent or suggest the wrong diagnosis. The absence of an RS complex in all precordial leads is easily recognizable and highly specific for the diagnosis of ventricular tachycardia. When an RS complex is present in one or more precordial leads, an RS interval of more than 100 msec is highly specific for ventricular tachycardia. This new stepwise approach may prevent diagnostic mistakes.