Fragmented narrow QRS complex: predictor of left ventricular dyssynchrony in non-ischemic dilated cardiomyopathy

A Comparative Study of Systolic and Diastolic Mechanical Synchrony in Canine, Primate, and Healthy and Failing Human Hearts

Aim: Mechanical dyssynchrony (MD) is associated with heart failure (HF) and may be prognostically important in cardiac resynchronization therapy (CRT). Yet, little is known about its patterns in healthy or diseased hearts. We here investigate and compare systolic and diastolic MD in both right (RV) and left ventricles (LV) of canine, primate and healthy and failing human hearts. Methods and Results: RV and LV mechanical function were examined by pulse-wave Doppler in 15 beagle dogs, 59 rhesus monkeys, 100 healthy human subjects and 39 heart failure (HF) patients. This measured RV and LV pre-ejection periods (RVPEP and LVPEP) and diastolic opening times (Q-TVE and Q-MVE). The occurrence of right (RVMDs) and left ventricular systolic mechanical delay (LVMDs) was assessed by comparing RVPEP and LVPEP values. That of right (RVMDd) and left ventricular diastolic mechanical delay (LVMDd) was assessed from the corresponding diastolic opening times (Q-TVE and Q-MVE). These situations were quantified by values of interventricular systolic (IVMDs) and diastolic mechanical delays (IVMDd), represented as positive if the relevant RV mechanical events preceded those in the LV. Healthy hearts in all species examined showed greater LV than RV delay times and therefore positive IVMDs and IVMDd. In contrast a greater proportion of the HF patients showed both markedly increased IVMDs and negative IVMDd, with diastolic mechanical asynchrony negatively correlated with LVEF. Conclusion: The present IVMDs and IVMDd findings have potential clinical implications particularly for personalized setting of parameter values in CRT in individual patients to achieve effective treatment of HF.

Fragmented QRS is associated with intraventricular dyssynchrony and independently predicts nonresponse to cardiac resynchronization therapy—Systematic review and meta‐analysis

Background

Fragmented QRS (fQRS) is postulated to be associated with ventricular dyssynchrony and might be able to predict a nonresponse to cardiac resynchronization therapy (CRT) implantation. In this systematic review and meta‐analysis, we aim to assess whether fQRS can be a marker of intraventricular dyssynchronies in patients with ischemic and nonischemic cardiomyopathy and whether it is an independent predictor of nonresponse in patients receiving CRT.

Methods

We performed a comprehensive search on topics that assesses fQRS and its association with intraventricular dyssynchrony and nonresponse to CRT up until September 2019.

Results

Fragmented QRS is associated with intraventricular dyssynchrony (OR 10.34 [3.39, 31.54], p < .001; I²: 80% with sensitivity 76.8%, specificity 77%, LR+ 3.3, and LR− 0.3). Subgroup analysis showed that fQRS is associated with intraventricular dyssynchrony in patients with narrow QRS complex (OR 20.92 [12.24, 35.73], p < .001; I²: 0%) and nonischemic cardiomyopathy (OR of 19.97 [12.12, 32.92], p < .001; I²: 0%). Fragmented QRS was also associated with a higher time‐to‐peak myocardial sustained systolic (Ts‐SD) (OR 15.19 [12.58, 17.80], p < .001; I²: 0% and positive Yu index (OR 15.61 [9.07, 26.86], p < .001; I²: 0%). Fragmented QRS has a pooled adjusted OR of OR of 1.70 [1.35, 2.14], p < .001; I²: 62% for association with a nonresponse to CRT. QRS duration is found to be higher in nonresponders group mean difference −8.54 [−13.38, −3.70], p < .001; I²: 70%.

Conclusion

Fragmented QRS is associated with intraventricular dyssynchrony and is independently associated with nonresponse to cardiac resynchronization therapy.

Inter- and intra-observer variability of visual fragmented QRS scoring in ischemic and non-ischemic cardiomyopathy

BACKGROUND

Fragmented QRS (fQRS) on a 12-lead ECG has been linked with adverse outcome. However, the visual scoring of ECGs is prone to inter- and intra-observer variability.

METHODS

Five observers, two experienced and three novel, assessed fQRS in 712 digital ECGs, 100 were re-evaluated to assess intra-observer variability. Fleiss and Cohen's Kappa were calculated and compared between subgroups.

RESULTS

The inter-observer variability for assessing fQRS in all leads combined was substantial with a Kappa of 0.651. Experienced observers only had a better agreement with a Kappa of 0.823. Intra-observer variability ranged from 0.736 to 0.880. In the subgroup with ventricular pacing the inter-observer variability was even significantly larger when compared to ECGs with normal QRS duration (Kappa 0.493 vs 0.664, p<0.001).

CONCLUSION

The visual assessment of QRS fragmentation is prone to inter- and intra-observer variability, mainly influenced by the experience of the observers, the underlying rhythm and QRS morphology.

Fragmented QRS for Risk Stratification in Patients Undergoing First Diagnostic Coronary Angiography

Background

Only a small proportion of patients referred for coronary angiography with suspected coronary artery disease (CAD) have the diagnosis of obstructive CAD confirmed by the exam. For this reason, further strategies for risk stratification are necessary.

Objective

To investigate the relationship of the presence of fragmented QRS (fQRS) on admission electrocardiogram with angiographically detected CAD and CAD severity in patients without known vascular diseases and myocardial fibrosis, undergoing first diagnostic coronary angiography.

Methods

We enrolled 336 consecutive patients undergoing coronary angiography for suspected CAD. The patients were divided into two groups according to the presence or absence of fQRS on admission. We compared the groups regarding the presence and severity of CAD.

Results

Seventy-nine (23.5%) patients had fQRS on admission. There was not a statistically significant difference between patients with fQRS (41.8%) and non-fQRS (30.4%), regarding the presence of CAD (p = 0.059). However, there was a statistically significant difference between patients with fQRS and non-fQRS regarding the presence of stenotic CAD (40.5% vs. 10.5%, p<0.001) and multi vessel disease (25,3% vs. 5.1%, p<0.001). The frequency of fQRS was significantly higher in patients with SYNTAX score >22 compared to patients with SYNTAX score ≤22.

Conclusions

Our findings suggest that fQRS may be an indicator of early-stage myocardial damage preceding the appearance of fibrosis and scar, and may be used for risk stratification in patients undergoing first diagnostic coronary angiography

[Fragmented QRS. Relevance in clinical practice]

The QRS complex represents the electrical depolarization of ventricular myocardium. In the case of an undisturbed depolarization, the QRS complex has a normal configuration and duration, but abnormal electrical conduction leads to widening of the QRS complex. The block of one of the Tawara branches results in a typical bundle branch block pattern. A QRS complex that cannot be classified as bundle branch block due to an atypical configuration and contains notched R or S waves is called a fragmented QRS. The underlying pathophysiologies are manifold and include myocardial scars induced by ischemic heart disease, myocardial fibrosis due to other diseases, primary cardiac pathologies as well as systemic diseases with cardiac involvement. Pathologies on the cellular level, such as ion channel dysfunctions, also correlate with fragmented QRS. Besides the diagnostic relevance, fragmented QRS is known to have prognostic properties, for example in identifying high risk patients with coronary artery disease, cardiomyopathy, Brugada syndrome and acquired long QT syndrome; however, fragmented QRS may also be detected in ECGs of healthy individuals.

Pathophysiological links, echocardiographic characteristics, and clinical implications of QRS morphology in patients with dilated cardiomyopathy

Heart failure is an important clinical problem worldwide. There is great interest in evaluating the relationship between electrocardiographic variations and dilated cardiomyopathy (DCM) since it has been used as a predictor of increased morbidity and mortality. The presence of fragmentation in the QRS complexes on 12-lead electrocardiogram (ECG) was reported as a marker of depolarization abnormality in patients with DCM. Previous studies have investigated the relation between QRS morphology and DCM. QRS morphology and duration are associated with clinical deterioration and increased mortality in patients with DCM. Although surface ECG provides valuable information on prognosis of these patients, echocardiographic methods have been used for further investigation of patients with DCM. The aim of the present review is to provide an overview of the pathophysiological links, echocardiographic characteristics and clinical implications of QRS morphology in patients with DCM.

Changes in left ventricular synchrony and systolic function in dilated cardiomyopathy patients with fragmented QRS complexes

AIMS

Fragmented QRS (f-QRS) complexes are associated with adverse cardiovascular events in patients with coronary heart disease; however, the effects on patients with dilated cardiomyopathy (DCM) remain elusive. This study is to investigate the changes of left ventricular (LV) synchrony and systolic function in DCM patients with f-QRS complexes.

METHODS AND RESULTS

Twenty DCM patients with f-QRS complexes and 29 DCM patients without f-QRS (n-QRS) complexes were enrolled. The LV segmental longitudinal, radial and circumferential time to peak strain and general longitudinal systolic strain, radial strain, circumferential strain were measured, respectively, by speckle tracking imaging. The LV segmental standard deviations and maximal differences were also calculated. The LV dyssynchrony was defined as the time in peak anteroseptal wall to posterior wall strain >130 ms or longitudinal strain delay index >25%. The mean QRS durations in f-QRS and n-QRS groups were not different (P = ns). The incidence of LV dyssynchrony was 15/20 (75%) vs. 5/29 (17%) in two groups (P < 0.01). Two patients died of sudden death in f-QRS group during 2 years follow-up; however, no death in n-QRS group (P < 0.05). Patients in f-QRS group showed worsening LV dyssynchrony in f-QRS group after 2 years follow-up (P < 0.05). Overall, LV function was comparable at baseline (P = ns), but had significantly worsened only in the f-QRS group (P < 0.05).

CONCLUSION

The f-QRS complex is significantly associated with LV dyssynchrony in DCM patients and can be used as a reliable index to evaluate ventricular synchrony and predict the prognosis in DCM patients with narrow QRS complexes.

The Predictive Value of Admission Fragmented QRS Complex for In-Hospital Cardiovascular Mortality of Patients with Type 1 Acute Aortic Dissection

BACKGROUND

Fragmented QRS (fQRS) arises from impaired ventricular depolarization due to heterogeneous electrical activation of ischemic and/or infarcted ventricular myocardium. The short- and long-term prognostic values of fQRS have been reported for myocardial infarction, heart failure, fatal cardiac arrhythmias, and sudden cardiac death. The aim of this study was to investigate the predictive value of admission fQRS complex for in-hospital cardiovascular mortality of patients with type 1 acute aortic dissection (AAD).

METHODS

In this retrospective study, 203 consecutive patients with type 1 AAD who had been admitted to either of two large-volume tertiary hospitals between December 2008 and October 2013 were included. The patients were divided into two groups according to the presence or absence of the fQRS complex on admission.

RESULTS

In-hospital cardiovascular mortality (P < 0.001), major adverse cardiovascular events (P < 0.001), acute renal failure (P = 0.022), multiorgan dysfunction (P < 0.001), and acute decompensated heart failure (P < 0.001) were observed to be significantly more frequent in the fQRS-positive group than in the fQRS-negative group. fQRS (odds ratio [95% confidence interval]: 4.184 [1.927-9.082], P < 0.001), operation duration (4.184 [1.927-9.082], P = 0.001), and Killip class IV (3.900 [1.699-8.955], P = 0.001) were found to be significant independent predictors of in-hospital cardiovascular mortality after adjustment of other risk factors in the multivariate analysis.

CONCLUSIONS

fQRS is a simple, inexpensive, and readily available electrocardiographic entity that provides an additional risk stratification level beyond that provided by conventional risk parameters in predicting in-hospital cardiovascular mortality in type 1 AAD.

Regression of fragmented QRS complex: a marker of electrical reverse remodeling in cardiac resynchronization therapy

BACKGROUND

Fragmented QRS (fQRS) marks inhomogeneous activation and asynchronous cardiac contraction. It has been proved that cardiac resynchronization therapy (CRT) could reverse geometrical remodeling as well as correct electrical dyssynchrony. We aimed to investigate whether fQRS changed corresponding to the therapeutic response to CRT.

METHODS

Patients who underwent de novo CRT implantation previously and had ≥1 follow-up between August 2012 and September 2013 in our hospital were investigated. Intrinsic electrocardiogram was recorded and fQRS in any lead was calculated. Response to CRT was defined as absolute improvement in left ventricular ejection fraction by ≥10% or by improvement >1 New York Heart Association class and without heart failure hospitalization.

RESULTS

A total of 75 patients (48 male, mean ages, 61 ± 9 years) were included in this study. At a median follow-up of 13 months, 57 patients had response to CRT. Responders had narrowed QRS (from 167 ± 23 ms to 158 ± 19 ms, P = 0.003) and reduced fQRS post-CRT. Nonresponders had QRS prolonging (from 151 ± 26 ms to 168 ± 16 ms, P = 0.033) and increase in fQRS. Eleven of 12 patients with reduced fQRS were responders and 8 of 12 with increased fQRS were nonresponders. Both changes in QRS and fQRS correlated strongly with CRT response (r = 0.389, P = 0.001 and r = 0.403, P = 0.000, respectively). Reduction of fQRS in ≥1 leads had high specificity (95%) in association to responders, though in low sensitivity (19%).

CONCLUSIONS

The changes in fQRS associated with therapeutic response to CRT. Regression of fQRS could be a maker of electrical reverse remodeling following CRT.

Variations of QRS Morphology in Patients with Dilated Cardiomyopathy; Clinical and Prognostic Implications

The QRS represents the simultaneous activation of the right and left ventricles, although most of the QRS waveform is derived from the larger left ventricular musculature. Although normal QRS duration is <100 millisecond (ms), its duration and shape are quite variable from patient to patient in idiopathic dilated cardiomyopathy (IDCM). Prolongation of QRS occurs in 14% to 47% of heart failure (HF) patients. Left bundle branch block (LBBB) is far more common than right bundle branch block (RBBB). Dyssynchronous left ventricular activation due to LBBB and other intraventricular conduction blocks provides the rationale for the use of cardiac resynchronization therapy with biventricular pacing in patients with IDCM. Fragmented QRS (fQRS) is a marker of depolarization abnormality and present in significant number of the patients with IDCM and narrow QRS complexes. It is associated with arrhythmic events and intraventricular dyssynchrony. The purpose of this manuscript is to present an overview on some clinical, echocardiographic and prognostic implications of various QRS morphologies in patients with IDCM.