Response to letter: Value of the aVR lead in differential diagnosis of atrioventricular nodal reentrant tachycardia

We appreciate Dr Di Toro's interest1 in our article ‘Value of the aVR lead in differential diagnosis of atrioventricular nodal reentrant tachycardia’, which was published online in Europace.2 We would like to clarify concerns about our statement that the ‘pseudo-r′ in aVR was more accurate than standard criteria’. Dr Di Toro points out that ‘the specificity of the pseudo-r′ in aVR and the terminal notching in aVL were identical in Majid's series. Although they did not make any statistical test to compare the signs, they concluded that pseudo-r′ in aVR was more accurate than standard criteria. This conclusion is not entirely correct. The pseudo-r′ in aVR show a better positive predictive value than terminal notching in aVL but it is dependent of prevalence of the sign (51.3% aVL notch in our series vs. 41% in Majid Haghjoo article)’.2 To clarify this issue, we draw Dr Di Toro's attention to our statement that ‘New criterion of pseudo-r′ in aVR had a higher sensitivity (absolute increase, 11–27%; P = 0.05), specificity (absolute increase, 6–11%; P = 0.02), positive predictive value (absolute increase, 5–15%; P = 0.02), and negative predictive value (absolute increase, 8–17%; P = 0.04) compared with the well-known criteria of pseudo-r′ in V1 and pseudo-s in inferior leads. Among the eight patients with pseudo-r′ in aVR without other ECG signs, AVNRT diagnosis was correctly made in all cases, whereas a correct diagnosis was made in two of three patients with isolated aVL notch’.2 Although sensitivity and specificity of aVL notch was higher than the standard criteria in your study, these differences did not reach statistical significance.3 Therefore, our conclusions are clear and evidence based. We finally agree with you that ‘pseudo-r′ wave in aVR and terminal notching in aVL are useful new tools in the differential diagnosis of the paroxysmal supraventricular tachycardia and all electrocardiographic criteria should be taken into account to make the diagnosis of atrioventricular node reentrant tachycardia’. Once again, we thank Dr Di Toro for his interest in the article and for his thoughtful comments. I hope this response helps clarify any remaining confusion. Conflict of interest: none declared.