QRS fragmentation can predict regional motion abnormality on imaging, finds study.

In recent years the search for new predictors of poor prognosis in CAD has revealed the presence of fragmented QRS (fQRS). Continuing this exciting arena of research, Torales et al have now shown that the presence of fQRS in the ECG has high specificity and a high positive predictive value of the existence of segmental myocardial motility disorders in patients with documented coronary artery disease (CAD). Their findings from a retrospective cross-sectional study were recently published in Indian Heart Journal.

The predictors of poor prognosis in CAD are decreased left ventricular function, ventricular remodeling, and the development of potentially malignant arrhythmias. The fQRS, evaluated on the 12-lead electrocardiogram (ECG), represents a delay in ventricular conduction caused by the presence of a myocardial scar. Even without being specific to CAD, it has been associated to an increased risk of mortality and arrhythmic events as an addition to the already known ejection fraction (EF).

fQRS is defined by the finding of additional notching within the QRS complex morphology in two contiguous leads corresponding to a major coronary artery territory, resulting in various RSR' patterns on the resting 12-lead ECG.

It is a simple marker of non-invasive electrocardiographic depolarization used to identify individuals at high risk of ventricular arrhythmias and sudden cardiac death in various clinical settings, including CAD.

In this cross-sectional study a total of 123 patients admitted with ischemic heart disease were enrolled and 81 out of 123 who had documentation of CAD by coronary angiography were taken up for further analysis. The aim was to correlate the presence of fQRS in a conventional 12-leads electrocardiogram (ECG) with myocardial regional motility disorders. 

1. fQRS was observed in 44% patients.

2. The most frequent location being the inferior wall (61%), followed by the anteroseptal and lateral walls (14% for both).

3. Of the 36 patients with fQRS, 30 had segmental disorders, while 6 did not.

4. Of the 45 patients without fQRS, 28 had segmental disorders, but 17 did not.

5. fQRS thus had a sensitivity of 52% and specificity of 74% , with a positive predictive value of 83%, a negative predictive value of 38% and a prevalence of 72%.

The study thus shows that the presence of QRS complex fragmentation in the electrocardiogram has a high specificity and a high positive predictive value of the existence of segmental disorders of myocardial contractility in patients with coronary artery disease.

"This has inherent clinical implication since with a simple electrocardiogram that is an efficient, fast, cheap and highly available diagnostic auxiliary method; we may assume that a patient may also have segmental parietal motility abnormalities of the ventricular myocardium:, noted the authors.

Fragmented QRS is a novel ECG parameter that can be assessed from an inexpensive, easily obtainable, and fast conventional procedure; a standard 12-lead ECG. Fragmented QRS complexes may represent conduction abnormalities or peri-infarction block related to myocardial scar or necrosis.

Therefore, fQRS is not only indicative of myocardial scar, but may also represent ischemic myocardium evocative of severe CAD. This fact is clinically relevant since it may enable fQRS to be used to detect patients with potentially salvageable myocardium who need to undergo revascularization.

Source: Indian Heart Journal: https://doi.org/10.1016/j.ihj.2021.03.010