On a Possible Mechanistic Association of QRS Duration and Atrial Fibrillation

Letter to Editor:

The excellent article by El‐Chami et alpublished in the March 2010 issue of Clinical Cardiology 1 reports on an association of electrocardiogram (ECG) QRS‐complex duration (QRSd) and atrial fibrillation (AF), based on a cohort of 25 268 patients from the National Registry to Advance Heart Health (ADVANCENT) registry emanating from 106 United States centers. Although the title appropriately reads as “QRS Duration Is Associated With Atrial Fibrillation in Patients With Left Ventricular Dysfunction,” the authors conclude in the manuscript and the Abstract that QRSd “may predict the occurrence” of AF. Prediction implies that one could foretell or say in advance what one believes will happen, and in the current context one would need a first ECG showing a prolonged QRSd and a second ECG at a later time showing AF. The authors' database includes a single ECG, and therefore they have shown merely an association between prolonged QRSd and AF. While one could associate mechanistically prolonged QRSd with the emergence of AF, one wonders whether AF by its presence or persistence could lead to increased QRSd. Both issues need to be explored in registries including a baseline ECG for baseline QRSd or presence of AF with subsequent ECGs over long periods of time to evaluate a possible mechanistic association of these 2 clinical entities. Perhaps one could “get more mileage” from the available data by exploring whether paroxysmal AF, persistent AF, and permanent AF had an ascending rate of QRSd. The authors found that 25.5% of their patients had AF, and the rate of paroxysmal AF was 46.4%, persistent AF was 41.1%, and unknown pattern was 12.5%; with these data, it may be of interest whether the QRSd of the patients with persistent AF was greater than the QRSd of the patients with paroxysmal AF, and whether such association was independent of other confounders. In this QRSd and AF association or mechanistic pathogenetic link, fibrosis of the ventricles and atria may be instrumental, as the authors are alluding to. Thus, in a study model with ≥ 2 ECGs, it behooves researchers to evaluate the baseline ECG showing sinus‐rhythm parameters of atrial remodeling, such as P‐wave duration or P‐wave dispersion along with QRSd, and then explore whether prolonged QRSd can independently predict the emergence of AF.