Fragmented QRS on electrocardiography as a predictor of myocardial scar in patients with hypertrophic cardiomyopathy

Catheter ablation of ventricular tachycardia: strategies to improve outcomes

Catheter ablation of ventricular arrhythmias has evolved considerably since it was first described more than 3 decades ago. Advancements in understanding the underlying substrate, utilizing pre-procedural imaging, and evolving ablation techniques have improved the outcomes of catheter ablation. Ensuring safety and efficacy during catheter ablation requires adequate planning, including analysis of the 12 lead ECG and appropriate pre-procedural imaging. Defining the underlying arrhythmogenic substrate and disease eitology allow for the developed of tailored ablation strategies, especially for patients with non-ischemic cardiomyopathies. During ablation, the type of anesthesia can affect VT induction, the quality of the electro-anatomic map, and the stability of the catheter during ablation. For high risk patients, appropriate selection of hemodynamic support can increase the success of VT ablation. For patients in whom VT is hemodynamically unstable or difficult to induce, substrate modification strategies can aid in safe and successful ablation. Recently, there has been an several advancements in substrate mapping strategies that can be used to identify and differentiate local late potentials. The incorporation of high-definition mapping and contact-sense technologies have both had incremental benefits on the success of ablation procedures. It is crucial to harness newer technology and ablation strategies with the highest level of peri-procedural safety to achieve optimal long-term outcomes in patients undergoing VT ablation.

Automated Quantification of Abnormal QRS Peaks From High-Resolution ECGs Predicts Late Ventricular Arrhythmias in Hypertrophic Cardiomyopathy: A 5-Year Prospective Multicenter Study

Background Patients with hypertrophic cardiomyopathy (HCM) are at risk of ventricular arrhythmia (VA) attributed to abnormal electrical activation arising from myocardial fibrosis and myocyte disarray. We sought to quantify intra-QRS peaks (QRSp) in high-resolution ECGs as a measure of abnormal activation to predict late VA in patients with HCM. Methods and Results Prospectively enrolled patients with HCM (n=143, age 53±14 years) with prophylactic implantable cardioverter-defibrillators had 3-minute, high-resolution (1024 Hz), digital 12-lead ECGs recorded during intrinsic rhythm. For each precordial lead, QRSp was defined as the total number of peaks detected in the QRS complex that deviated from a smoothing filtered version of the QRS. The VA end point was appropriate implantable cardioverter-defibrillator therapy during 5-year prospective follow-up. After 5 years, 21 (16%) patients had VA. Patients who were VA positive had greater QRSp (6.0 [4.0-7.0] versus 4.0 [2.0-5.0]; P<0.01) and lower left ventricular ejection fraction (57±11 versus 62±9; P=0.038) compared with patients who were VA negative, but had similar established HCM risk metrics. Receiver operating characteristic analysis revealed that QRSp discriminated VA (area under the curve=0.76; P<0.001), with a QRSp ≥4 achieving 91% sensitivity and 39% specificity. The annual VA rate was greater in patients with QRSp ≥4 versus QRSp <4 (4.4% versus 0.98%; P=0.012). In multivariable Cox regression, age <50 years (hazard ratio [HR], 2.53; P=0.009) and QRSp (HR per QRS peak, 1.41; P=0.009) predicted VA after adjusting for established HCM risk metrics. In patients aged <50 years, the annual VA rate was 0.0% for QRSp <4 compared with 6.9% for QRSp ≥4 (P=0.012). Conclusions QRSp predicted VA in patients with HCM who were eligible for an implantable cardioverter-defibrillator after adjusting for established HCM risk metrics, such that each additional QRS peak increases VA risk by 40%. QRSp <4 was associated with a <1% annual VA risk in all patients, and no VA risk among those aged <50 years. This novel ECG metric may improve patient selection for prophylactic implantable cardioverter-defibrillator therapy by identifying those with low VA risk. These findings require further validation in a lower risk HCM cohort. Registration URL: https://www.clinicaltrials.gov; Unique identifier: NCT02560844.

Predicting arrhythmias in primary prevention heart failure patients: picking up the fragments

Identifying patients with high-risk heart failure (HF) who would benefit from an implantable cardioverter-defibrillator (ICD) remains controversial. A potential marker for arrhythmic sudden death is fragmented QRS (fQRS). fQRS is the notching and slurring of the QRS complex in a 12-lead ECG and it indicates abnormal ventricular depolarisation and myocardial scarring and fibrosis. However, before fQRS complex can be included into selection criteria for ICD therapy, more complete reporting is required on their association with malignant arrhythmias, left ventricular remodelling and myocardial scarring/fibrosis in patients with HF. The molecular basis of the fQRS-arrhythmia-fibrosis connection in HF also needs to be explored. It is not widely appreciated that changes in the QRS complex and phases 0 and 1 of the ventricular action potential occur before contraction and predetermine Ca²⁺ release during contraction and later Ca²⁺ sparks. It is currently not known whether the different zig-zag patterns of the QRS are associated with aberrant Ca²⁺ cycling and arrhythmogenic sparks in patients with HF.

ICD indication in hypertrophic cardiomyopathy: which algorithm to use?

OBJECTIVE

This study aimed to evaluate the agreement in the indication of implantable cardioverter-defibrillators in patients with Hypertrophic cardiomyopathy, as per the 2014 European Society of Cardiology and 2020 American Heart Association recommendations, and evaluate fragmented QRS as a predictor of cardiovascular outcome.

METHODS

Retrospective cohort with 81 patients was evaluated between 2019 and 2021. Patients with hypertrophic cardiomyopathy ≥16 years old were included. Exclusion criteria include secondary myocardiopathy and follow-up <1 year. Kappa coefficient was used to determine the agreement. Survival and incidence curves were determined by Kaplan-Meier method. A p<0.05 was considered significant.

RESULTS

The fragmented QRS was identified in 44.4% of patients. There were no differences between patients with and without fragmented QRS regarding clinical parameters, echocardiography, fibrosis, and sudden cardiac death risk. During follow-up of 4.8±3.4 years, there was no sudden cardiac death, but 20.6% patients with implantable cardioverter-defibrillator had at least one appropriate shock. Three of the seven appropriate shocks occurred in European Society of Cardiology low- to moderate-risk patients. Three shocks occurred in moderate-risk patients and four in American Heart Association high-risk patients. Overall recommendations agreement was 64% with a kappa of 0.270 (p=0.007). C-statistic showed no differences regarding the incidence of appropriate shock (p=0.644).

CONCLUSION

sudden cardiac death risk stratification algorithms present discrepancies in implantable cardioverter-defibrillator indication, both with low accuracy.

QRS fragmentation is associated with increased risk of ventricular arrhythmias in high-risk patients; Data from the SMASH 1 Study

INTRODUCTION

QRS fragmentation (fQRS), defined as the presence of additional spikes within the QRS complex, has been associated with myocardial conduction abnormalities and arrhythmogenicity.

OBJECTIVE

We aimed to assess whether fQRS is associated with incident ventricular arrhythmias (VA) in high-risk patients treated with implantable cardioverter-defibrillator (ICD) for primary and secondary prevention.

METHODS

In a prospective observational multicenter study, we included 495 patients treated with ICD. fQRS was analyzed according to previously validated criteria, by two physicians blinded for outcome data. Incident VA were obtained from ICD recordings.

RESULTS

ECG recordings interpretable for fQRS were available in 459 patients (93%), aged 66 ± 12 years with left ventricular ejection fraction 40% ± 13%. fQRS was present in 52 patients (11%) with comparable baseline characteristics to patients without fQRS, except higher age, higher prevalence of coronary artery disease (CAD), lower prevalence of cardiomyopathy, and more frequently a secondary prevention ICD indication. Among patients with native QRS, those with fQRS had similar QRS duration and axis to those without fQRS. During 3.1 ± 0.7 years follow-up, 126 patients (28%) had ≥1 VA . fQRS was associated with increased risk of VA (HR 3.41 [95% CI 2.27-5.13], p < .001), which persisted after adjusting for age, gender, sex, BMI, CAD, heart failure, renal function, ICD indication, QRS duration, QRS axis, Q waves, and bundle branch block. fQRS was more strongly associated with VA in patients with a primary (HR 6.05 [95% CI 3.16-11.60]) versus secondary (HR 2.39 [95% CI 1.41-4.04]) ICD indication (p-for-interaction = .047).

CONCLUSIONS

fQRS is associated with threefold increased risk of VA in high-risk patients, independent of established risk factors.

Dilated left ventricle with multiple outpouchings — a severe congenital ventricular diverticulum or left-dominant arrhythmogenic cardiomyopathy: A case report

BACKGROUND

Left-dominant arrhythmogenic cardiomyopathy (LDAC) is a relatively rare disease characterized by poor prognosis that exacerbates the incidence of sudden cardiac death and ventricular arrhythmias. Clinically, LDAC is constantly overlooked or misdiagnosed as myocardial infarction, myocarditis, and dilated cardiomyopathy, owing to atypical and nonspecific clinical manifestations at an early stage.

CASE SUMMARY

A 57-year-old woman was diagnosed with sinus bradycardia and chronic bifascicular block during a health check. She occasionally experienced mild chest pain and paroxysmal palpitation during activity in the past 2 years. Comprehensive auxiliary examinations, including electrocardiogram, echocardiography, coronary computerized tomography angiography, and magnetic resonance imaging, revealed that she had LDAC instead of congenital ventricular diverticulum. The physicians prescribed standard oral therapy for heart failure and implantable cardioverter-defibrillator. Consequently, her left ventricular systolic function and symptoms remained stable at the 2-year follow-up after discharge.

CONCLUSION

Based on this case, clinicians need to be aware of LDAC in patients with localized left ventricular lesions and multiple electrocardiographic abnormalities. Multimodality cardiovascular imaging is effective in identification of multiple types of cardiomyopathy and cardiac inner structures.

Relationship Between Fragmented QRS Complex and Left Ventricular Fibrosis and Function in Patients With Danon Disease

Background

Fragmented QRS (f-QRS) complex on the surface ECG is a cardiac conduction abnormality that indicates myocardial scarring. The relationship between the f-QRS complex and cardiac status in patients with Danon disease (DD) remains unclear and will be explored in this study.

Methods

Patients with genetically confirmed DD and cardiac magnetic resonance imaging (CMR) examinations were recruited from multiple centers. The number of leads, pattern, score, and segmental distribution of the f-QRS complex were assessed by surface 12-lead ECG. Cardiac status, such as left ventricular (LV) volume, function, and extent of late gadolinium enhancement (LGE), was demonstrated by CMR. The segmental distribution of LGE was also assessed. Correlations between the f-QRS and cardiac status were assessed.

Results

Fifteen patients (14 men) with DD who underwent 12-lead ECG and CMR imaging were included. The f-QRS complex was documented in all patients (n = 15, 100%). Three patterns of f-QRS were found, with the notched R/S pattern (74%) being the most common, followed by fragmented QRS (16%) and various RSR' (11%). The fragmented QRS pattern showed an association with a higher level of myocardial fibrosis (LGE > 35%). The burden of f-QRS in each patient was assessed by the number of leads with f-QRS (median 7, range 2–12) and the f-QRS score (median 9, range 2–33). In the correlation analysis, the f-QRS score was positively correlated with LGE% (r = 0.726, p = 0.002), negatively correlated with LV ejection function (LVEF; r = −0.617, p = 0.014) as evaluated by CMR. In the local distribution, f-QRS score and LGE% were both predominant in the LV free wall but did not correlate well among the anterior, lateral, and inferior segments.

Conclusion

In this DD cohort, the quantitative f-QRS was correlated well with myocardial fibrosis burden and LV dysfunction in general. This finding suggests that f-QRS can be used as a simple screening tool to assess cardiac status in patients with DD.

Review article: the best of 2019

In 2019, a total of 70 original scientific papers or reviews were published in Acta Cardiologica. In this paper, we focus on the 10 best papers that we selected based upon the innovative character and/or upon the clinical relevance of their research. In different domains of cardiology, we highlight the most important findings from these 10 best research papers.

Clinical and molecular characterization of seven patients with Danon disease

Danon disease is an X-linked glycogen storage disease characterized by skeletal myopathy, cardiomyopathy and intellectual impairment. It is caused by a loss-of-function mutation in the lysosome-associated membrane protein-2 (LAMP2) gene. In the present study, exon and boarding intron analysis of 96 cardio disease-associated genes was performed in 770 patients with hypertrophic cardiomyopathy (HCM) using second-generation sequencing. Next, the identified mutations were confirmed in family members of the patients and 300 healthy controls. Detailed clinical, electrocardiographic (ECG) and echocardiographic findings were recorded. A pathogenic mutation in LAMP2 was identified in 7 patients who phenotypically presented with HCM. A total of four patients had a fragmented QRS complex (fQRS) on surface ECG. In addition, two patients presented with ventricular preexcitation with a short PR interval. Compared with the patients with protein kinase AMP-activated non-catalytic subunit γ2 syndrome and Fabry disease, the 7 patients with Danon disease presented at an earlier age, had a smaller left atrial size, a thinner maximal left ventricular wall thickness and a lower probability of pacemaker implantation. Compared with 12 sex- and age-matched patients with sarcomere-protein mutations, the 4 patients with Danon disease had a lower left ventricular outflow tract gradient and worse diastolic function. The present study provided a comprehensive comparison of different pathologies presenting with HCM and reported on features of early-onset Danon disease, including the characteristic preexcitation and fQRS on ECG. This may provide valuable information that may be utilized for the early diagnosis and treatment of patients with Danon disease. The present study was registered as a clinical trial with ClinicalTrials.gov (Sep. 2, 2016; registry no. NCT02888132).

Fragmented QRS on surface electrocardiography as a predictor of cardiac mortality in patients with SARS-CoV-2 infection

Aims

Although severe acute respiratory syndrome coronavirus-2 (SARS-CoV-2) infection is mainly a respiratory system disease, recent studies reported that cardiac injury is associated with poor outcomes in this population. There are few studies which assessed standard electrocardiogram (ECG) as a prognostic tool during the course of SARS-CoV-2 infection. The aim of this study is to identify the relationship between of ECG parameters and prognosis of patients infected with SARS-CoV-2.

Method and results

A total of 114 consecutive patients with a confirmed diagnosis of SARS-CoV-2 infection between March 2020 and May 2020 were included in the study. Standard 12‑lead surface ECG was reviewed for presence of fragmented QRS (fQRS), abnormal Q wave, T wave inversion, and duration of QRS. fQRS was observed in 36.8% (n = 42) of the patients who had SARS-CoV-2. Patient groups with and without fQRS did not differ in terms of age, gender, the presence of comorbid diseases and medical treatment. Hospitalization duration, intensive care unit(ICU) requirement, all-cause mortality, and cardiac mortality were found to be higher in patients with fQRS (all p values <0.05). There was a positive correlation between QRS duration and duration of hospital stay (p < 0.001, r = 0.421). QRS duration was also found to be associated with intensive care need, all-cause mortality, and cardiac mortality.

Conclusion

Our data shows that QRS duration and the presence of fQRS on standard ECG can help to identify patients with worse clinical outcome admitted for SARS-CoV-2 infection.

Quantitative fragmented QRS has a good diagnostic value on myocardial fibrosis in hypertrophic obstructive cardiomyopathy based on clinical-pathological study

Background

To investigate the relationship between fragmented QRS (fQRS) quantified by a new method and myocardial fibrosis (MF) and the diagnostic value of quantitative fQRS (Q-fQRS) to detect MF in hypertrophic obstructive cardiomyopathy (HOCM) patients based on histological validation.

Methods

We performed a retrospective study that included 69 patients with HOCM who underwent ventricular septal surgery. Nine individuals who died from accidents were studied as a control reference for the histological parameters. Septal myocardium samples were subjected to Masson’s trichrome staining to quantify the collagen volume fraction (CVF). An fQRS pattern was defined as the presence of additional R waves or RSR’, evidenced by notched R or S wave on electrocardiography (ECG). The Q-fQRS was quantified as the total amount of deflections in the QRS complex in all 12 routine ECG leads together. Cardiac magnetic resonance imaging was conducted, and late gadolinium enhancement (LGE) was measured at 2, 4, 6 and 8 standard deviations (SDs).

Results

Of the 69 patients, fQRS was documented in 38 (55.1%) patients, the mean number of leads with fQRS was 3.7 ± 1.6, and the mean Q-fQRS was 17 ± 7.2. Compared with HOCM patients without fQRS, HOCM patients with fQRS had a higher CVF and more LGE at 6 SD (P < 0.001; P = 0.040). Q-fQRS was correlated with CVF (r = 0.640, P < 0.001), and Q-fQRS showed the best correlation with LGE measured at 8 SD (r = 0.379, P = 0.002). Multivariate regression analyses revealed that Q-fQRS was independently associated with the extent of CVF in HOCM patients after adjusting for age, sex, body surface area and the extent of LGE at 6 SD (P < 0.001). When the patients were divided into subgroups with normal CVF or high CVF according to the CVF in controls, Q-fQRS and LGE at 6SD showed similar diagnostic value in detecting patients with high CVF, with sensitivities of 66.7% vs 68.6%, specificities of 76.7% vs 72.4%, and accuracies of 71% vs 70.3%.

Conclusions

HOCM patients with fQRS showed more extensive MF. Q-fQRS was an independent predictor for MF and had a good diagnostic value, with a sensitivity of 66.7% and specificity of 76.7%, in identifying patients with higher fibrotic burden.

New Appearance of Fragmented QRS as a Predictor of Ventricular Arrhythmic Events in Patients With Hypertrophic Cardiomyopathy

BACKGROUND

Multiple spikes in the QRS complex (fragmented QRS [fQRS]) on 12-lead electrocardiography have been associated with ventricular arrhythmic events (VAEs) in patients with hypertrophic cardiomyopathy (HCM). The aim of this study was to assess the association between new appearances of fQRS and cardiac events in patients with HCM.Methods and Results:The association between baseline fQRS and cardiac events, namely VAEs, heart failure-related hospitalization, and all-cause death, was evaluated retrospectively in 146 HCM patients (46 patients with fQRS, 100 without fQRS). The median follow-up was 5.3 years. Cardiac events occurred in 29 patients with baseline fQRS and 32 patients without baseline fQRS (63% vs. 32%; P<0.001). VAEs occurred in a significantly larger percentage of patients with than without baseline fQRS (54% vs. 23%, respectively; P<0.001). Of the 100 patients without baseline fQRS, 33 had a new appearance of fQRS during the 4.6-year follow-up, whereas 67 did not. VAEs occurred more frequently in the 33 patients with the appearance of fQRS than in those without (42% vs. 13%, respectively; P=0.001). Multivariable analysis showed that the new appearance of fQRS documented before VAEs was associated with VAEs (hazard ratio 4.29, 95% confidence interval 1.81-10.2; P=0.001).

CONCLUSIONS

The new appearance of fQRS was associated with an increased risk of VAEs in HCM patients.

Fragmented QRS - Its significance

Fragment QRS (fQRS) complex is a myocardial conduction abnormality that indicates myocardial scar. It is defined as additional notches in the QRS complex. Though initially fQRS was defined in the setting of normal QRS duration (<120 m s), later it has been expanded to include conditions with wide QRS complexes as in bundle branch block, ventricular ectopy and paced rhythm, when more than 2 notches are present. It is an important, yet often overlooked marker of mortality and arrhythmic events in many cardiac diseases. The significance of fQRS lies in the fact that it just requires a surface ECG for its recording and the value of information about the condition of the heart it dispenses based on the clinical setting. We review the role of fQRS in predicting adverse cardiac events in various conditions.

Fragmented QRS as a candidate marker for left ventricular nonrecovery in patients with peripartum cardiomyopathy

BACKGROUND

Fragmented QRS (fQRS) complex, with various morphology, has been recently described as a diagnostic criterion of several cardiac diseases. However, there are little data regarding the prognostic role of fQRS in peripartum cardiomyopathy (PPCM) patients. We aimed to investigate the effect of fQRS on predicting left ventricular (LV) nonrecovery in patients with peripartum cardiomyopathy (PPCM).

METHODS

Ninety patients (mean age: 34.7 ± 6.5 years) with the diagnosis of PPCM were analyzed retrospectively. The median follow-up period of was 67.0 (12.0-192.0) months. Fragmented QRS was defined as the presence of various RSR' patterns (QRS duration < 120 ms) with or without Q wave, which include an additional R wave (R' prime) or notching of the R wave or S wave, or the presence of more than one R' (fragmentation) without typical bundle branch block. Recovery of LV function was defined as the presence of LV ejection fraction (EF) >45%.

RESULTS

Of the patients, 54 (60%) did not recover LV function at the last follow-up visit (nonrecovery group), while 36 of the patients (40%) exhibited LV recovery (recovery group). LV ejection fraction (EF) and fQRS were identified as independent predictors of LV nonrecovery in patients with PPCM (odds ratio OR: 5.546, 95% confidence interval CI: 0.792-0.979, p = .019 and OR: 5.986, 95% CI: 1.313-11.787, p = .014, respectively).

CONCLUSION

Our data firstly indicated that presence of fQRS was a significant predictor of LV nonrecovery in patients with PPCM. The fQRS might assist in identifying high-risk patients.