Review of methods to derive the heartbeat-evoked potential: past practices and future directions.
The heartbeat-evoked potential (HEP) is an implicit, electrophysiological marker of cortical heartbeat processing and interoception, with increasing clinical relevance. However, on the scalp, HEP are low-amplitude signals mixed with cardiac field artefacts (CFA), requiring signal processing pipelines to separate HEP from CFA. This review evaluates current analytical approaches and addresses methodological gaps in HEP pipelines. A scoping review of the literature was conducted focusing on previously published HEP studies. This was to extract HEP processing methods and parameters used in EEG (199 included papers) and MEG (8 included papers). Parameters investigated included the HEP window, filters, baseline correction window, epoch timeframes, minimum RR intervals, epoch amplitude rejection threshold, and CFA removal. EEG and MEG studies revealed clear heterogeneity and variability in the methods used to derive HEP. These clear inconsistencies in HEP parameter use and reporting would appear to challenge the level replicability between studies. In order to ensure reproducibility and transparency, publications should report critical values for reliable HEP extraction, emphasising the need for standardised methods to enhance study comparability and reproducibility.