As in the pacemaker studies in syncope, initial results were promising; sham control decreased the margin of benefit caused by pacing itself; by changing the form of pre-event detection and pacing before cardio inhibition, there was significance in the therapeutic effect. In the case of CNA, the effect on modulation of physiology and elimination of the CI effect is clearly demonstrated through the ECVS, and with the atropine test, the possibility of placebo effect is unknown, but the proof of denervation is a fact.

In the study by Gopinathannair et al., the efficacy was similar in both groups, with similar complication rates. However, the elimination of the vagal effect should have been done in the CNA group to have a fair comparison. In any study, especially in a new technique as CNA, the lack of strict control showing the vagal effect elimination, proven, for example, with ECVS, impairs the result of the CNA and reduces the strength of the conclusions. Multiple questions should be addressed in the ongoing and future investigations, comparing the results of CNA with pacemaker in prospective and multicenter studies, and randomization with long-term follow-up including the methodological variations of the CNA technique [3, 7, 8]; however, all of these possibilities depends on performing CNA through objective measurement of the denervation effect by ECVS.