Late Potentials in Healthy Subjects

Objective: Criteria for detection of late potentials have not yet been standardized, but the criteria recommended by ESC/AHA/ACC are widely used. In this investigation, the prevalence of late potentials is studied in an age stratified healthy population with likelihood of coronary artery disease < 5%. Relation between signal‐averaged variables and clinical variables was studied. Methods: Signal‐averaged ECGs were recorded using Butterworth filters at 40 and 250 Hz. The following three time‐domain parameters were evaluated: QRS duration (duration of the amplified, filtered QRS complex); LPD (duration of the late potentials, i.e., duration from the point of time when the magnitude of the main complex becomes lower than 40 μV); and RMS40 (root mean square of the activity within the last 40 ms of the amplified, filtered QRS complex). Results: QRS duration was significantly longer in men than in women, and was correlated to the mass of the left ventricle (LVM). The combination LPD and RMS40 gave the highest prevalence of late potentials. The prevalence of late potentials was 25%. Conclusion: Standard criteria should be used with great caution, and normal limits should be established in each laboratory to a preselected noise level. QRSD should be included within the definition of reference limits and should be gender matched. Even though there is correlation between LVM and the QRSD, the upper normal limit of QRSD based on LVM matching is unchanged.