If the conclusions of this study are to be implemented in general practice, several other limitations and possible sources of bias should be borne in mind. First, ICD EGM tracings were filtered in a specific way by the recording system (between 0.05 and 300 Hz), which is not the filtering used for standard ICD EGM tracings, at least by some manufacturers. Second, both the definition of the gold standard and the visual analysis were performed by 2 observers, but they were not blinded to other information. Third, ICDs from several manufacturers were included in the study. Although the investigators analyzed the potential impact of ICD manufacturer in spatial resolution and found no significant differences, the sample size was too small for a rigorous comparison. As a result, one cannot be assured of a lack of impact of ICD manufacturer. Furthermore, the near-field ICD EGMs are truly bipolar in some ICDs but not in others, and the superior vena cava coil participates in the coil-to-can configuration from some ICDs but not from others. In addition, it has been shown that the configuration of the ICD EGM during sinus rhythm differs between 2 of the defined brands, and these factors could potentially influence spatial resolution (5). Finally, all patients had post-myocardial infarction VT. It is unclear if the conclusions can be maintained for other VT substrates.