Accuracy of precordial ECG electrode placement by clinically authorised trainees in NHS practice

Introduction: Incorrect precordial electrocardiogram (ECG) electrode placement is a recognised source of diagnostic error, yet limited evidence exists regarding accuracy among clinically authorised cardiac physiology trainees. This study aimed to evaluate the accuracy of precordial ECG electrode placement in trainees deemed competent to perform independent ECG acquisition within NHS clinical practice.

Methods: A covert cross-sectional observational study was conducted involving 36 clinically authorised trainees from 15 NHS trusts. Participants performed standard 12-lead ECG recordings under routine practice conditions. Electrode placement was assessed against The Society for Cardiac Science and Technology (SCST) 2024 guidelines, and displacement was measured in horizontal and vertical planes.

Results: A total of 216 precordial leads were analysed. Overall, 81% of participants placed electrodes outside guideline-recommended locations, with only a minority of participants achieving fully correct placement. Displacement was most frequent in leads V1 and V2, with consistent directional patterns observed, including lateral deviation from the sternal borders and inferior displacement. While median displacement was 0 mm across several leads, substantial variability was evident, with errors of up to 65 mm horizontally and 50 mm vertically. Lower clinical experience was associated with a higher likelihood of displacement (p < 0.001), although neither SCST accreditation nor ECG workload was associated with improved accuracy.

Conclusion: These findings demonstrate that significant inaccuracies in ECG electrode placement persist despite formal competency assessment. Enhanced training focusing on anatomical landmark identification and regular reassessment of practical skills are required to improve the reliability of ECG acquisition in clinical practice.