Author + information
- Julian O.M. Ormerod, MA, PhD and
- Oliver J. Rider, DPhil∗ ()
- ↵∗Oxford Centre for Clinical Magnetic Resonance, John Radcliffe Hospital, Headley Way, Headington, Oxford OX3 9DU, United Kingdom
We read with interest the study from van der Harst et al. (1). The authors show an association between 52 genetic loci and various features of the resting 12-lead electrocardiograph (ECG). ECG-based criteria are notably poor in estimating myocardial mass. The Sokolow-Lyon criteria remain perhaps the most frequently used in clinical practice. The authors of the original study report a mere 32% sensitivity in detecting left ventricular hypertrophy (LVH) from their original dataset (2), with the standard used to assess LVH being a chest radiograph rather than echocardiography or magnetic resonance scanning as would be used today. Newer criteria perform only incrementally better. It may well be, therefore, that the ECG changes measured in the present study reflect important factors, other than increased myocardial mass. For example, conduction velocity has a strong influence on QRS duration. Also, voltage criteria for LVH are commonly met in patients with (genotype positive–phenotype negative) hypertrophic cardiomyopathy before developing any LVH (3). One of the single nucleotide polymorphisms reported was in a promoter of SCN5A. Mutations in this sodium channel are associated with many conditions that affect the surface ECG: conduction disease, dilated cardiomyopathy (commonly associated with left bundle branch block), and channelopathies such as long QT type 3 and Brugada syndromes.
Most strikingly, increased body mass index tends to obscure ECG evidence of increased myocardial mass, which would potentially dilute the strength of the association reported. A simple adjustment can improve the sensitivity of ECG-based criteria for LVH in patients with an increased body mass index by up to 30% without significantly decreasing the specificity (4). If body mass index data are available for patients in this cohort, then this adjustment may in fact strengthen these associations.
Please note: Both authors have reported that they have no relationships relevant to the contents of this paper to disclose.
- American College of Cardiology Foundation
- van der Harst P.,
- van Setten J.,
- Verweij N.,
- et al.
- Panza J.A.,
- Maron B.J.
- Rider O.J.,
- Ntusi N.,
- Bull S.C.,
- et al.