Key result
Limb lead interchanges occurred in 3.4% of ECGs and were significantly more frequent with Holter devices compared to 12-lead ECGs (7.5% vs 0.8%, P < .0001).
Why the study?
How frequent are limb lead interchanges in thorough QT/QTc studies and how effectively are they identified by different methods?
Observational (n=484)
How frequent are limb lead interchanges in thorough QT/QTc studies and how effectively are they identified by different methods?
Absolute Event Rate: 7.5% vs 0.8%
p-value: p=< .0001
Limb lead interchanges occur in 3.4% of ECGs in thorough QT studies, highlighting the need for dedicated quality control to prevent inaccurate QT measurements.
Limb lead interchanges may compromise QTc accuracy in thorough QT studies; leaves open optimal detection strategies across device types.
The investigators analyzed 85,133 electrocardiograms (ECGs) recorded in 484 subjects from 5 thorough QT/QTc studies (3 using Holter devices, 2 using 12-lead ECGs) for inadvertent limb lead interchanges using a dedicated quality control process in a central ECG laboratory. Limb lead interchanges were present in 2919 (3.4%) ECGs in 17.9% of subjects and were more frequent with Holter devices (7.5% vs 0.8%, P < .0001), where leads remain connected for prolonged periods, affecting data from several time points. Left arm-left leg interchange was seen in 54% of 12-lead ECGs and right arm-left arm interchange in 38%. The ECG device itself could identify 21.7% of interchanges, whereas experienced readers blinded to subject and visit identified 79% of interchanges; 21% of interchanges were identified only during the quality control process. If correctly identified, QT measurement could be performed in a precordial lead. If undiagnosed, incorrect QT interval measurements and morphological diagnosis may confound results.
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Salvi et al. (2011) conducted an observational in Subjects in thorough QT/QTc studies (n=484). Holter devices vs. 12-lead ECGs was evaluated on Frequency of limb lead interchanges (p=< .0001). Limb lead interchanges occurred in 3.4% of ECGs and were significantly more frequent with Holter devices compared to 12-lead ECGs (7.5% vs 0.8%, P < .0001).
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