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We read with interest Thomson et al’s article “ECG in suspected pulmonary embolism” which was published in Postgraduate Medical Journal in January 2019. We would like to bring to your attention another important but little-known cause of S1Q3T3, namely left arm – V2 ECG lead misplacement. This occurs when the yellow ECG cables are misplaced and can easily be misdiagnosed as a pulmonary embolism. A characteristic appearance occurs which we believe is pathognomonic for LA – V2 misplacement. In addition to S1Q3T3, a tall R wave in lead III is seen (1). In a study of 62 patients in whom we recorded both a normal and an LA V2 ECG lead misplacement, we observed that the presence of S1Q3T3R3 is highly statistically significant for left arm -V2 lead misplacement (P=0) (1). It is important to exclude lead misplacement, or the patient may have incorrect treatment administered or the correct treatment withheld because of an error in recording an ECG. Of 230 unrecognised ECG lead misplacements in our hospital, 10.9% were left arm – V2 (2).
After a thorough search of the literature we have identified only 2 brief reports on this topic (3,4). Therefore, it is highly likely that if it does occur then ECG features will inadvertently be attributed to pulmonary embolism and managed inappropriately.
1. Lynch R, Ballesty L, Kuan SC, Ponnambolam Y. Left arm – V2 ECG Lead Misplacement by Colour: a largely unknown entity which can easily be Misdiagnosed as a Pulmo...
1. Lynch R, Ballesty L, Kuan SC, Ponnambolam Y. Left arm – V2 ECG Lead Misplacement by Colour: a largely unknown entity which can easily be Misdiagnosed as a Pulmonary Embolism. J Electrocardiol 2019; 53: e18. DOI: 10.1016/j.jelectrocard.2019.01.064. Presented at the International Conference on Electrocardiology, Chiba, Japan, 2018.
2. Lynch RM. ECG Lead Misplacement: Experience from an Irish District Hospital. Abstract accepted for International Conference in Emergency Medicine, Seoul, South Korea, June 2019.
3. Javier García-Niebla, Pablo Llontop García. An unusual case of electrode misplacement: left arm and V2 electrode reversal. J Electrocardiol 2008; 41:380-381.
4. Lynch RM. ECG lead misplacement by colour: what difference does it make? Sud J Med Sci 2014; 9 (3):145-150.