Fragmented QRS and other depolarization abnormalities as a predictor of mortality and sudden cardiac death. Curr Opin Cardiol. 2010;25:59-64. [PMID: 19881337 DOI: 10.1097/hco.0b013e328333d35d]

Analysis of QRS complex morphology in children and adolescents with obstructive sleep apnea syndrome

Obstructive sleep apnea syndrome (OSAS) leads to many cardiovascular, neurologic, metabolic, and neurocognitive consequences. Conduction deficits, deviations in electrical axis, and changes in QRS morphology reflect the impairments in cardiac muscle activity and underlie the cardiovascular complications of OSAS. Here we aimed to determine the relationship between OSAS and changes in the cardiac conduction system in children and adolescents. During the 6-month duration of the study, all children having the diagnosis of OSAS in Sleep and Disorders Unit following a full-night polysomnography (PSG) were consecutively evaluated. ECGs were performed and analyzed in the Division of Pediatric Cardiology, Department of Pediatrics. The maximum spatial vector size (QRSmax), QRS electrical axis (EA), left and right ventricular hypertrophy, and the presence of fragmented QRS (fQRS) or prolonged R or S wave were examined in detail. A total of 17 boys with OSAS and 13 healthy boys participated in the study. The mean QRSmax and the QRSmax on V5 derivative were significantly lower in the patient group compared to those in the control group (p = 0.011 and p = 0.017, respectively). EA was similar between the two groups. While none of the patients with OSAS nor the control group had left ventricular hypertrophy, only one boy with OSAS had right ventricular hypertrophy according to ECG-derived analysis. The percentage of fQRS or notched R or S waves was significantly higher in patients with OSAS compared to healthy controls (p = 0.035), especially in children below the age of 5 years (p = 0.036).  Conclusion: This study demonstrated that male children and adolescents with OSAS have a combination of QRS complex changes characterized by low QRS voltages, and increased frequency of fragmented QRS. These findings reflect that the electrical remodeling and structural remodeling of the myocardium are considerably affected by OSAS in children and adolescents, leading to ventricular changes and intraventricular conduction problems. What is Known: • Pediatric obstructive sleep apnea syndrome (OSAS) characterized by recurrent intermittent hypoxemia, hypercapnia, and sleep fragmentation results in sympathetic nervous system activation, increased inflammation, and hypoxic endothelial dysfunction. When left untreated, OSAS leads to many cardiovascular, neurologic, metabolic and neurocognitive consequences, and also to sudden infant death syndrome in young children, probably due to the involvement of the cardiac conduction system. What is New: • This study demonstrated that mean QRSmax was significantly lower in male children and adolescents with OSAS, reflecting the structural and electrical remodeling of the myocardium, and one boy with OSAS had RVH according to ECG-derived analysis. The percentage of fQRS or notched R or S waves was much higher in boys with OSAS, especially in children below the age of five years. These finding showed that myocardium was considerably affected to impair the intraventricular conduction in younger children with OSAS.

The Fragmented QRS Complex in Lead V1: Time for an Update of the Athlete's ECG?

Differentiating between ECG patterns related to athletes' heart remodeling and pathological findings is a challenge in sports cardiology. As the significance of fragmented complex in athletes remains uncertain, this study aimed to assess the presence of fragmented QRS in lead V1 (fQRSV1) among young athletes and its association with heart adaptations and arrhythmias. Young athletes referred for annual pre-participation screening receiving a maximal exercise testing and transthoracic echocardiography from January 2015 to March 2021 were included. The study included 684 young athletes. The prevalence of fQRSV1 was 33%. Subjects with fQRSV1 had higher exercise capacity and indexes of right ventricular function and remodeling. Among highly trained athletes, the fQRSV1 group demonstrated also increased left ventricular wall thickness. No significant association existed between fQRSV1 and exercise-induced arrhythmias, even in highly trained athletes. The high prevalence of fQRSV1 in young athletes is associated with training-induced heart adaptations but not exercise-induced ventricular arrhythmias.

Evaluation and Management of Sudden Death Risk in Repaired Tetralogy of Fallot

Although substantial progress has been made to prevent sudden cardiac death in repaired tetralogy of Fallot patients, ventricular arrhythmia and sudden death continue to be major causes of morbidity and mortality in these patients. Greater survival in contemporary cohorts has been attributed to enhanced surgical techniques, more effective management of heart failure, and increased efforts in risk stratification and management of ventricular arrhythmias. More recently, our understanding of predictive risk factors has evolved into personalized risk prediction tools that rely on comprehensive demographic, imaging, functional, and electrophysiological data. However, the universal applicability of these different scoring systems is limited due to differences between study cohorts, types of anatomic repair, imaging modalities, and disease complexity. Noninvasive risk stratification is critical to identify those who may derive benefit from catheter ablation or cardioverter defibrillator implantation for primary prevention. Ultimately, assessment and risk stratification by a multidisciplinary team is crucial to analyze the various complex factors for every individual patient and discuss further options with patients and their families.

A State-of-the-Art Review on Sleep Apnea Syndrome and Heart Failure

Heart failure (HF) affects many patients worldwide every year. It represents a leading cause of hospitalization and still, today, mortality remains high, albeit the progress in treatment strategies. Several factors contribute to the development and progression of HF. Among these, sleep apnea syndrome represents a common but still underestimated factor because its prevalence is substantially higher in patients with HF than in the general population and is related to a worse prognosis. This review summarizes the current knowledge about sleep apnea syndrome coexisting with HF in terms of morbidity and mortality to provide actual and future perspectives about the diagnosis, evaluation, and treatment of this association.

Biomarkers to Predict Sudden Cardiac Death

Sudden cardiac death (SCD) is a common disorder and an unsolved issue for health care providers. Despite several risk factors for SCD, some cases experience SCD as an initial presentation of cardiovascular disease. Prediction of individuals at increased risk for SCD is important for implementing community-based approaches and individual-based therapies with high costs, such as implantable defibrillators. This chapter discusses the potential role of biomarkers in predicting SCD in different cardiovascular diseases.

Fragmented QRS on far-field intracardiac electrograms as a predictor of arrhythmic events

BACKGROUND

Studies suggest that fragmented QRS (fQRS) can predict arrhythmic events in various cardiac diseases. However, the association between fQRS recordings on intracardiac electrogram (EGM) and ventricular arrhythmic events remains unknown.

METHODS

We enrolled 51 patients (age, 62 ± 12 years; 40 men) with an implantable cardioverter-defibrillator (ICD) and structural heart disease and evaluated surface electrocardiogram (ECG) and EGM measurement of fQRS and the association between fQRS and arrhythmic events.

RESULTS

fQRS was detected on surface ECG and ICD-EGM in 12 (23.5%) and 15 (29.4%) patients, respectively. fQRS was detected more frequently on ICD-EGM in patients with fQRS on surface ECG than in patients without fQRS (7/12 [58.3%] vs 8/39 patients [20.5%], P = .01). Appropriate ICD therapies were documented in 16 patients. Among these patients, fQRS was detected more frequently on surface ECG and ICD-EGM in patients with appropriate ICD therapies (8/16, 50.0%; P = .001 and 11/16, 68.9%; P < .001). Nonsustained ventricular tachycardia was significantly more frequent in patients with appropriate ICD therapies (15/16, 93.8%; P = .04). Multiple logistic regression analysis showed that fQRS on ICD-EGM was a predictor of arrhythmic events (P = .03). Kaplan-Meier survival analysis revealed that ICD therapies were significantly more frequent among patients with fQRS on both surface ECG and ICD-EGM than among those without fQRS (66.7% vs 6.6%, P < .001).

CONCLUSION

The presence of fQRS on ICD-EGM can be a predictor of arrhythmic events in ICD patients. Surface ECG and ICD-EGM measurement may help predict ventricular arrhythmic events.

High prevalence of fragmented QRS on electrocardiography in Japanese patients with diabetes irrespective of metabolic syndrome

AIMS/INTRODUCTION

Fragmented QRS (fQRS) on electrocardiography is a marker of myocardial fibrosis and myocardial scar formation. This study aimed to clarify the relationship of fQRS with diabetes mellitus and metabolic syndrome (MetS) in Japanese patients.

MATERIALS AND METHODS

Approximately 702 individuals who had a routine health checkup at the Hokuriku Health Service Association (Toyama, Japan) in October 2014 were enrolled and categorized into one of the following four groups based on MetS and diabetes mellitus status: with diabetes mellitus (+) MetS+ (164 participants); diabetes mellitus+ without MetS (Mets-; 103 participants); diabetes mellitus- MetS+ (133 participants); and diabetes mellitus- MetS- (302 participants). fQRS was assessed using the results of electrocardiography.

RESULTS

The prevalence of fQRS was statistically higher in patients with diabetes mellitus+ MetS+ (37%) and diabetes mellitus+ MetS- (35%), than those with diabetes mellitus- MetS+ (14%) or diabetes mellitus- MetS- (10%; P < 0.0001). Significant differences were observed between the fQRS(+) and fQRS(-) groups for age, sex, waist circumference, heart rate, hypertension, hemoglobin A1c, total cholesterol, MetS and diabetes mellitus. The area under the receiver operating characteristic curve for traditional risk factors and diabetes mellitus was 0.72 (P = 0.0007, 95% confidence interval 0.67-0.76), and for traditional risk factors and MetS it was 0.67 (P = 0.28, 95% confidence interval 0.62-0.72). Patients with diabetes mellitus had more than threefold higher likelihood of showing fQRS (odds ratio 3.41; 95% confidence interval 2.25-5.22; P < 0.0001) compared with the reference group without diabetes mellitus, after adjusting for age, sex, dyslipidemia, hypertension and waist circumference.

CONCLUSIONS

fQRS was observed more frequently in diabetes mellitus patients than in MetS and control individuals. Diabetes mellitus was the most significant determinant for fQRS among MetS and other traditional metabolic risk factors.

The Selvester QRS score as an estimative of myocardial injury in acute chagasic patients from the Brazilian Amazon

BACKGROUND

In the Brazilian Amazon, a new epidemiological profile of Chagas disease transmission, the oral route, has been detected and cited as being responsible for the increase in acute cases in Brazil. The clinical evaluation of acute Chagas disease (ACD) has been a challenge since it can progress to a chronic phase with cardiac alterations, and the follow-up by modern diagnostic methods is very difficult due to the socio-geographical characteristics of the Brazilian Amazon. Thus, alternatives should be sought to alleviate this problem. We conducted a study to evaluate subjects with ACD using the 12-lead ECG QRS score (Selvester score) as an estimative of myocardial injury progression before and after ACD treatment.

METHODS

The study included indigenous subjects from the Amazon region with ACD in clinical follow-up at the Fundação de Medicina Tropical Dr. Heitor Vieira Dourado (FMT-HVD) Chagas Disease outpatient clinic in the state of Amazonas, Brazil. The control group consisted of 31 healthy volunteers with no history of heart disease and no reactive serology for Chagas disease. Baseline ECG was performed in all subjects. The Selvester scoring method was performed according to the standardized guide (< 3 points: no myocardial injury,> 3: points × 3% = % of the predicted LV infarction).

RESULTS

A total of 62 subjects were included, 31 as cases and 31 as controls. The mean follow-up of the case group was 17 months. The control group presented normal ECG. The case group presented 13 alterations before treatment and 11 after. Nineteen individuals presented scores > 3 points, 6 before and 13 after. In 19.36% of subjects, myocardial injury was found before treatment and in 41.94% after treatment.

CONCLUSION

This is the first study that uses the Selvester score (SS) to predict myocardial injury in subjects with ACD. The results of this study suggest the significant presence of myocardial injury from the beginning of treatment to the period post treatment of ACD, which demonstrates that the SS can be applied for stratification and follow-up of Chagas disease in the Amazon region.

Presence of fragmented QRS may be associated with complex ventricular arrhythmias in patients with type-2 diabetes mellitus

BACKGROUND

Ventricular arrhythmias (VAs) are frequent in diabetes mellitus (DM) patients. Myocardial fibrosis is one of the components of diabetic cardiomyopathy secondary to DM. Fragmented QRS (fQRS) on electrocardiography (ECG) has been shown to be a marker of myocardial fibrosis. In this study, we aimed to investigate the association between fQRS and complex VAs in patients with DM.

METHODS

Three hundred and thirty-six consecutive patients who were diagnosed with DM were included in the study. The control group consisted of 275 age- and sex-matched healthy individuals. ECG and transthoracic echocardiography were performed in all the patients. fQRS was defined as additional R' wave or notching/splitting of S wave in two contiguous ECG leads. All the patients underwent 24-h Holter monitoring and VAs were classified using Lown's scoring system. Lown class ≥ 3 VAs were considered as complex VAs.

RESULTS

As compared to the healthy individuals, prevalence of fQRS (37.5% vs. 6.9%, p < .001) and complex VAs (14% vs. 0%, p < .001) were significantly higher in patients with DM. Furthermore, complex VAs (28.4% vs. 6.4%, p < .001) were significantly higher in DM patients with fQRS. In multiple logistic regression analysis, DM duration (OR: 1.510, 95% CI:1.343 to 1.698; p < .001) and presence of fQRS (OR: 3.262, 95% CI: 1.443 to 7.376; p = .004) were independent predictors for complex VAs.

CONCLUSIONS

The presence of fQRS may be associated with complex VAs in patients with DM. Therefore, fQRS may be used as a predictor of complex VAs and the risk of sudden death in patients with DM.

R-Wave Singularity: A New Morphological Approach to the Analysis of Cardiac Electrical Dyssynchrony

R-wave singularity (RWS) measures the intermittence or discontinuousness of R waves. It has been broadly used in QRS (QRS complex of electrocardiogram) detection, electrocardiogram (ECG) beats classification, etc. In this article, we novelly developed RWS to the analysis of QRS morphology as the measurement of ventricular dyssynchrony and tested the hypothesis that RWS could enhance the discrimination between control and acute myocardial infarction (AMI) patients. Holter ECG recordings were obtained from the Telemetric and Holter ECG Warehouse database, among which database Normal was extracted as normal controls (n = 202) and database AMI (n = 93) as typical subjects of autonomic nervous system dysfunction and cardiac electrical dyssynchrony with high risk for cardiac arrhythmias and sudden cardiac death. Experimental results demonstrate that RWS measured by Lipschitz exponent calculated from 5-min Holter recordings was significantly less negative in early AMI and late AMI than that in Normal subjects for overall, elderly, and elderly male groups, which suggested the heterogeneous depolarization of the ventricular myocardium during AMI. Receiver operating characteristic curve analyses show that combined with heart rate variability parameters, Lipschitz exponent provides higher accuracy in distinguishing between the patients with AMI and healthy control subjects for overall, elderly, elderly male, and elderly female groups. In summary, our study demonstrates the significance of using RWS to probe the cardiac electrical dyssynchrony for AMI. Lipschitz exponent may be valuable and complementary for existing cardiac resynchronization therapy and autonomic nervous system assessment.

Importance of electrocardiographic markers in predicting cardiac events in children

ECG is a common diagnostic tool in medical practice. Sudden cardiac death (SCD) is a rare but devastating event. The most common cause of SCD in the young is a primary arrhythmic event, which is often produced by malignant ventricular arrhythmia. Several electrocardiographic markers for ventricular repolarization and depolarization have been proposed to predict this arrhythmic risk and SCD in children. Although many of these parameters can easily be used in clinical practice, some of them need specific techniques for interpretation. In this review, we summarized the current knowledge regarding the clinical importance and the ability of these ECG parameters to predict adverse cardiac events in the pediatric population.

Artificial intelligence algorithm for predicting cardiac arrest using electrocardiography

BACKGROUND

In-hospital cardiac arrest is a major burden in health care. Although several track-and-trigger systems are used to predict cardiac arrest, they often have unsatisfactory performances. We hypothesized that a deep-learning-based artificial intelligence algorithm (DLA) could effectively predict cardiac arrest using electrocardiography (ECG). We developed and validated a DLA for predicting cardiac arrest using ECG.

METHODS

We conducted a retrospective study that included 47,505 ECGs of 25,672 adult patients admitted to two hospitals, who underwent at least one ECG from October 2016 to September 2019. The endpoint was occurrence of cardiac arrest within 24 h from ECG. Using subgroup analyses in patients who were initially classified as non-event, we confirmed the delayed occurrence of cardiac arrest and unexpected intensive care unit transfer over 14 days.

RESULTS

We used 32,294 ECGs of 10,461 patients and 4483 ECGs of 4483 patients from a hospital were used as development and internal validation data, respectively. Additionally, 10,728 ECGs of 10,728 patients from another hospital were used as external validation data, which confirmed the robustness of the developed DLA. During internal and external validation, the areas under the receiver operating characteristic curves of the DLA in predicting cardiac arrest within 24 h were 0.913 and 0.948, respectively. The high risk group of the DLA showed a significantly higher hazard for delayed cardiac arrest (5.74% vs. 0.33%, P < 0.001) and unexpected intensive care unit transfer (4.23% vs. 0.82%, P < 0.001). A sensitivity map of the DLA displayed the ECG regions used to predict cardiac arrest, with the DLA focused most on the QRS complex.

CONCLUSIONS

Our DLA successfully predicted cardiac arrest using diverse formats of ECG. The results indicate that cardiac arrest could be screened and predicted not only with a conventional 12-lead ECG, but also with a single-lead ECG using a wearable device that employs our DLA.

Prognostic value of fragmented QRS complex in patients with acute myocardial infarction

BACKGROUND

Several factors and risk stratification tools have been studied to determine the prognosis of acute coronary syndrome. Fragmented QRS (fQRS) is a marker of myocardial scar and its prognostic role has recently been demonstrated. The present study aimed to investigate the association between the presence of fQRS in electrocardiogram and the prognosis of ST-segment elevation and non-ST-segment elevation myocardial infarction (STEMI and NSTEMI).

METHODS

A total of 661 patients with myocardial infarction (MI) were enrolled in a retrospective study. Based on the presence of fQRS in admission electrocardiogram, patients were divided into two groups. All patients were followed up for 6 months, and all major adverse cardiovascular events (MACE) were recorded.

RESULTS

The mean age of patients was 61.3 ± 1.2 years, and 71.7% were male. In the acute phase, the detection rates of regional wall motion abnormality and aortic valve insufficiency were higher in positive fQRS compared to negative fQRS group (p = 0.003). The incidence of total MACE was significantly higher in the positive fQRS compared to the negative fQRS group among all patients and in both STEMI and NSTEMI subgroups (p < 0.001). Based on multivariate analysis, the presence of fQRS and hypertension were the strongest predictors of total MACE at 6‑month follow-up (odds ratio [OR] = 5.929; 95% confidence interval [CI] = 3.620-9.709; p < 0.001 and OR = 2.220; 95% CI = 1.390-3.547; p < 0.001, respectively).

CONCLUSION

Regardless of the type of MI, it was found that the presence of fQRS on admission electrocardiogram can be implemented in risk stratification tools in patients with acute MI.

Fragmented QRS and subclinical left ventricular dysfunction in individuals with preserved ejection fraction: A speckle-tracking echocardiographic study

INTRODUCTION

Fragmented QRS (fQRS) complex on routine 12-lead electrocardiogram (ECG) predicts adverse outcomes in patients with cardiovascular diseases. In addition, it has been found to be associated with subclinical myocardial dysfunction in chronic diseases. We sought to investigate the relationship between the presence of fQRS with the myocardial functions in individuals free from known systemic cardiovascular diseases.

METHODS

In a case-control study, we evaluated normal individuals from March 2017 to February 2018. All participants underwent a 2-dimensional transthoracic echocardiographic examination using tissue Doppler imaging (TDI) and speckle-tracking echocardiography. In addition, all participants were examined using a 12-lead surface ECG, and patients with fQRS and a group of age- and sex-matched controls without fQRS were enrolled in our study.

RESULTS

The patients' mean age was 40.3 ± 10.7 and 35.4 ± 11.2 years in fQRS-positive and fQRS-negative groups, respectively (P = .110). Patients with fQRS had significantly lower values of apical left ventricular global longitudinal strain (LV GLS) in 2-chamber (16.9 ± 2.5 vs. 20.5 ± 3.3, P < .001), 4-chamber (16.9 ± 3.4 vs. 20.1 ± 3, P = .001), LAX views (17.7 ± 2.8 vs. 20.8 ± 3.5, P = .001), and averaged LV GLS (17 ± 2.6 vs. 20.4 ± 2.7, P < .001) values compared to patients without fQRS. In a multivariate analysis, averaged LV GLS and smoking history were independent predictors for positive fQRS.

CONCLUSION

The presence of fQRS on 12-lead ECG in healthy population was associated with lower values of LV GLS compared to normal individuals without fQRS.

Quantitative Approach to Fragmented QRS in Arrhythmogenic Cardiomyopathy: From Disease towards Asymptomatic Carriers of Pathogenic Variants

Fragmented QRS complexes (fQRS) are common in patients with arrhythmogenic cardiomyopathy (ACM). A new method of fQRS quantification may aid early disease detection in pathogenic variant carriers and assessment of prognosis in patients with early stage ACM. Patients with definite ACM (n = 221, 66%), carriers of a pathogenic ACM-associated variant without a definite ACM diagnosis (n = 57, 17%) and control subjects (n = 58, 17%) were included. Quantitative fQRS (Q-fQRS) was defined as the total amount of deflections in the QRS complex in all 12 electrocardiography (ECG) leads. Q-fQRS was scored by a single observer and reproducibility was determined by three independent observers. Q-fQRS count was feasible with acceptable intra- and inter-observer agreement. Q-fQRS count is significantly higher in patients with definite ACM (54 ± 15) and pathogenic variant carriers (55 ± 10) compared to controls (35 ± 5) (p < 0.001). In patients with ACM, Q-fQRS was not associated with sustained ventricular arrhythmia (p = 0.701) at baseline or during follow-up (p = 0.335). Both definite ACM patients and pathogenic variant carriers not fulfilling ACM diagnosis have a higher Q-fQRS than controls. This may indicate that increased Q-fQRS is an early sign of disease penetrance. In concealed and early stages of ACM the role of Q-fQRS for risk stratification is limited.

Ventricular Arrhythmias in Patients with Obstructive Sleep Apnea

Obstructive Sleep Apnea (OSA) is a prevalent condition thought to increase in the future. Being mostly undiagnosed, the most serious complications are cardiovascular diseases, among which are arrhythmias. Controversy remains as to whether OSA is a primary etiologic factor for ventricular arrhythmias, because of the high incidence of cardiovascular comorbidities in OSA patients. Howev-er, there is mostly a strong evidence of a relation between OSA and ventricular arrhythmias. A few mechanisms have been proposed to be responsible for this association and some electrocardiographic changes have also been demonstrated to be more frequent in OSA patients. Treatment of OSA with Continuous Positive Airway Pressure (CPAP) has the potential to reduce arrhythmias and confer a mortality benefit.

Prognostic significance of QRS fragmentation and correlation with infarct size in patients with anterior ST-segment elevation myocardial infarction treated with percutaneous coronary intervention: Insights from the INFUSE-AMI trial

BACKGROUND

QRS fragmentation (fQRS) is believed to reflect myocardial scar formation in patients with coronary disease. Whether early formation of fQRS in patients with ST-segment elevation myocardial infarction (STEMI) treated with percutaneous coronary intervention (PCI) is correlated with infarct size and prognosis is unknown. We assessed the prognostic value of fQRS at 60min post-PCI and its correlation with infarct size in patients with anterior STEMI managed with primary PCI.

METHODS

The INFUSE-AMI trial enrolled 452 patients with anterior STEMI undergoing primary PCI. Electrocardiograms (ECGs) were performed at baseline and 60min post-PCI. Infarct size was evaluated using cardiac magnetic resonance imaging at 30days post-PCI. Target vessel failure (TVF) was defined as the composite of cardiac death, target vessel myocardial infarction, or ischemia-driven target vessel revascularization. Study groups were defined as patients with versus without fQRS at 60min post-PCI.

RESULTS

Out of 421 patients with ECG data 60min post-PCI, 68 patients (16.2%) had fQRS. Patients with versus without fQRS had similar baseline characteristics and infarct size (16.9%±8.7% vs. 16.1%±10.5%, p=0.62), but patients with fQRS had higher adjusted risk of 1-year TVF (adjusted HR 2.27, 95% CI 1.06-4.89, p=0.036) and a trend toward a higher risk of the composite cardiac death or target vessel myocardial infarction (9.0% vs. 4.1%, p=0.08) at 1year.

CONCLUSION

fQRS in patients with STEMI is associated with TVF but does not correlate with infarct size.

Fragmentation of QRS complex during ventricular pacing is associated with ventricular arrhythmic events in patients with left ventricular dysfunction

BACKGROUND

QRS fragmentation (fQRS) during baseline ventricular conduction, a myocardial fibrosis marker, is associated with increased risk of ventricular tachyarrhythmias but may not manifest unless ventricular activation change is provoked. We examined the association of fQRS during right ventricular (RV) pacing with death and ventricular tachyarrhythmia in patients with left ventricular (LV) dysfunction undergoing electrophysiology study (EPS).

METHODS AND RESULTS

Study participants had LV dysfunction (ejection fraction < 50%) undergoing EPS from January 2002 to May 2014 at Mayo Clinic in Rochester, Minnesota. fQRS during RV stimulation involved >2 notches on R/S waves identified in ≥2 contiguous standard electrocardiographic leads representing anterior, inferior, or lateral ventricular segments. Primary outcomes were ventricular tachyarrhythmias that were symptomatic or required intervention and total and cardiac deaths. In all, 528 patients participated (mean age, 65 years; male sex, 80%). Of them, 312 (59%) had ischemic cardiomyopathy and mean (SD) left ventricular ejection fraction (LVEF) of 33.2% (9.5%); 457 (87%) had implantable cardiac devices (implanted defibrillator, n  =  380). Mean (SD) follow-up was 3.2 (3.0) years. fQRS during RV pacing was observed in 292 patients (60%) in any ventricular segment. Patients with fQRS during RV pacing had 2.5 higher rate of ventricular tachyarrhythmia events than patients with no fQRS (hazard ratio [95% CI], 2.45 [1.5-4.2]; P < 0.01), after correcting for baseline ventricular conduction defect and QRS duration, LVEF, inducible sustained ventricular tachycardia, diabetes mellitus, chronic kidney disease, and ischemic cardiomyopathy.

CONCLUSIONS

RV stimulation can unmask fQRS, and it is associated with increased risk of ventricular tachyarrhythmia in LV dysfunction.

Electrocardiogram changes and atrial arrhythmias in individuals carrying sodium channel SCN5A D1275N mutation

INTRODUCTION

The cardiac sodium channel SCN5A regulates atrioventricular and ventricular depolarization as well as cardiac conduction. Patients with cardiac electrical abnormalities have an increased risk of sudden cardiac death (SCD) and cardio-embolic stroke. Optimal management of cardiac disease includes the understanding of association between the causative mutations and the clinical phenotype. A 12-lead electrocardiogram (ECG) is an easy and inexpensive tool for finding risk patients.

MATERIALS AND METHODS

A blood sample for DNA extraction was obtained in a Finnish family with 43 members; systematic 12-lead ECG analysis was performed in 13 of the family members carrying an SCN5A D1275N mutation. Conduction defects and supraventricular arrhythmias, including atrial fibrillation/flutter, atrioventricular nodal re-entry tachycardia (AVNRT) and junctional rhythm were searched for.

RESULTS

Five (38%) mutation carriers had fascicular or bundle branch block, 10 had atrial arrhythmias; no ventricular arrhythmias were found. Notching of the R- and S waves - including initial QRS fragmentation - and prolonged S-wave upstroke were present in all the affected family members. Notably, four (31%) affected family members had a stroke before the age of 31 and two experienced premature death.

CONCLUSIONS

A 12-lead ECG can be used to predict arrhythmias in SCN5A D1275N mutation carriers. Key messages The 12-lead ECG may reveal cardiac abnormalities even before clinical symptoms occur. Specific ECG findings - initial QRS fragmentation, prolonged S-wave upstroke as well as supraventricular arrhythmias - were frequently encountered in all SCN5A D1257N mutation carriers. ECG follow-up is recommended for all SCN5A D1275N mutation carriers.

Assessment of the association between the presence of fragmented QRS and the predicted risk score of sudden cardiac death at 5 years in patients with hypertrophic cardiomyopathy

OBJECTIVE

It has been shown that the presence of fragmented QRS (fQRS) is associated with poor prognosis in many cardiovascular diseases and in patients with hypertrophic cardiomyopathy (HCM). However, no study has shown an association with the absolute risk score of sudden cardiac death. The aim of this study was to determine the relationship between QRS and the predicted risk score of sudden cardiac death at 5 years (HCM Risk-SCD) in HCM patients.

METHODS

In total, 115 consecutive HCM patients were included in this prospective observational study. The patients were divided into two groups according to the presence [fQRS(+) group (n=65)] or absence [fQRS(-) group (n=50)] of fQRS on a 12-lead electrocardiogram (ECG).

RESULTS

The HCM Risk-SCD (%) HCM Risk-SCD (>6%) values and some echocardiographic parameters, including ventricular extrasystole, ventricular tachycardia, cardiopulmonary resuscitation, implantable cardioverter defibrillator implantation, appropriate shock, and heart failure at the time of admission, were significantly higher in the fQRS(+) group than in the fQRS(-) group (all p<0.05). Both univariate and multivariate analyses revealed fQRS and New York Heart Association (NYHA) class as independent predictors of HCM Risk-SCD. In a receiver operating characteristic (ROC) curve analysis, an HCM Risk-SCD value of >4 was identified as an effective cut-off point in fQRS for HCM. An HCM Risk-SCD value of >4 yielded a sensitivity of 77% and a specificity of 76%.

CONCLUSION

fQRS is determined to be an independent high-risk indicator of HCM Risk-SCD. It seems to be associated with increased ventricular arrhythmias and some echocardiographic parameters.

Short-term Prognosis of Fragmented QRS Complex in Patients with Non-ST Elevated Acute Myocardial Infarction

Background:

There remains significant debate as to the relationship between fragmented QRS (fQRS) complexes on electrocardiogram (ECG) and acute myocardial infarction (AMI). Few studies have reported on this relationship in non-ST elevated AMI (NSTEMI), and thus, we attempt to assess this relationship and its potential short-term prognostic value.

Methods:

This was a single-center, observational, retrospective cohort study. A total of 513 consecutive patients (399 men, 114 women) with NSTEMI within 24 h who underwent coronary angiography at our department, between January 1, 2014, and December 31, 2014. Patients were divided into 2 groups according to the presence or absence of fQRS complex on the admission ECG. fQRS complexes were defined as the existence of an additional R’ or crochetage wave, notching in the nadir of the S wave, RS fragmentation, or QS complexes on 2 contiguous leads. All patients were followed up for 6 months, and all major adverse cardiac events (MACE) were recorded.

Results:

In this study, there were 285 patients with fQRS ECG in the 513 patients with NSTEMI. The number of patients with 0–2 coronary arteries narrowed by ≥50% in fQRS group were less while patients with 3 narrowed arteries were more than in the non-fQRS group (P = 0.042). There were fewer Killip Class I patients in the fQRS group (P = 0.019), while Killip Class II, III, and IV patients were more in the fQRS group than in the non-fQRS group (P = 0.019). Left ventricular ejection fraction levels were significantly lower in the fQRS group (P = 0.021). Baseline total cholesterol, low-density lipoprotein, creatinine, creatine kinase, homocysteine, high-sensitivity C-reactive protein (CRP), and red blood cells distribution width levels were significantly higher in the fQRS group. Total MACE (MACE, P = 0.028), revascularization (P = 0.005), and recurrent angina (P = 0.005) were also significantly greater in the fQRS group. On final logistic regression analysis, after adjusting for baseline variables, the following variables were independent predictors of fQRS: Coronary artery narrowing (P = 0.035), Killip classification (P = 0.026), and total cholesterol (P = 0.002). The following variables were found to be independent predictors of preoperative MACE: Hemoglobin (P = 0.000), gender (P = 0.026), fQRS (P = 0.016), and time from myocardial infarction to balloon or coronary artery bypasses grafting (P = 0.013).

Conclusions:

The fQRS complexes are commonly present in NSTEMI and the fQRS complexes are an independent predictor of MACE in NSTEMI patients. The number of narrowed coronary arteries, Killip classification, and total cholesterol are all independent predictors of the fQRS complexes.

The relationship between fragmented QRS and functional significance of coronary lesions

BACKGROUND

Recently fragmented QRS (fQRS) on electrocardiography (ECG) has been introduced as a predictor of myocardial scarring and myocardial ischemia in coronary artery disease (CAD).

OBJECTIVE

The aim of this study was to investigate the relationship between fQRS and fractional flow reserve (FFR) results in patients with the intermediate degree of coronary artery stenosis.

METHODS

A total of 301 consecutive patients who underwent coronary angiography (CAG) and FFR measurement for intermediate coronary artery stenosis were included in the study. The study patients were divided into two groups: the low FFR group (FFR value of ≤0.80) and normal FFR (FFR value of >0.80) group. Both groups were compared in terms of the presence of fQRS.

RESULTS

Of 301 patients, fQRS was detected in 128 (42.5%) and low FFR was detected in 115 (38.2%). In the low FFR group, fQRS was significantly higher (P<0.001). Multivariate analysis showed that fQRS was an independent predictor of myocardial ischemia in patients with intermediate coronary stenosis (OR=7.202, CI 95%, 4.195-12.367; p<0.001). The presence of fQRS had 70% sensitivity and 74% specificity for the prediction of FFR≤0.80.

CONCLUSION

In clinical practice, the presence of fQRS on ECG is associated with myocardial ischemia in patients with intermediate coronary stenosis.

QRS Fragmentation Patterns Representing Myocardial Scar Need to Be Separated from Benign Normal Variants: Hypotheses and Proposal for Morphology based Classification

The presence of a fragmented QRS complex (fQRS) in two contiguous leads of a standard 12-lead electrocardiogram (ECG) has been shown to be an indicator of myocardial scar in multiple different populations of cardiac patients. QRS fragmentation is also a predictor of adverse prognosis in acute myocardial infarction, coronary artery disease, and ischemic cardiomyopathy and a prognostic tool in structural heart diseases. An increased risk of sudden cardiac death associated with fQRS has been documented in patients with ischemic cardiomyopathy and hypertrophic cardiomyopathy. However, fQRS is also frequently observed in apparently healthy subjects. Thus, a more detailed classification of different QRS fragmentations is needed to identify the pathological fragmentation patterns and refine the role of fQRS as a risk marker of adverse cardiac events and sudden cardiac death. In most studies fQRS has been defined by the presence of an additional R wave (R′), or notching in the nadir of the S wave, or the presence of >1 R′ in two contiguous leads corresponding to a major coronary territory. However, this approach does not discriminate between minor and major fragmentations and the location of the fQRS is also neglected. In addition to this, the method is susceptible to large interobserver variability. We suppose that some fQRS subtypes result from conduction delays in the His-Purkinje system, which is a benign finding and thus can weaken the prognostic values of fQRS. The classification of fQRSs to subtypes with unambiguous definitions is needed to overcome the interobserver variability related issues and to separate fQRSs caused by myocardial scarring from benign normal variants. In this paper, we review the anatomic correlates of fQRS and the current knowledge of prognostic significance of fQRS. We also propose a detailed fQRS classification for research purposes which can later be simplified after the truly pathological morphologies have been identified. The research material of our study consist of 15,245 ECGs from the random general population and approximately six thousands (n = 6,241) ECGs from subjects with a known cardiac disease.

Presence of Fragmented QRS Complexes in Patients with Obstructive Sleep Apnea Syndrome

BACKGROUND

Obstructive sleep apnea syndrome (OSAS) is a disease with increasing prevalence, which is mainly characterized by increased cardiopulmonary mortality and morbidity. It is well-known that OSAS patients have increased prevalence of cardiovascular diseases including coronary heart disease, heart failure, and arrhythmias. The aim of this study was to evaluate the presence of prolonged and fragmented QRS complexes, which have previously been associated with cardiovascular mortality, in OSAS patients.

METHODS

Our study included 51 patients (mean age 41.6 ± 10.1 years) who were recently diagnosed with OSAS (apnea-hypopnea index [AHI] ≥5 events/h) and never received therapy. The control group consisted of 34 volunteers (mean age 43.1 ± 11.6 years) in whom OSAS was excluded (AHI <5 events/h). The longest QRS complexes was measured in the 12-lead electrocardiogram (ECG) and the presence of fragmentation in QRS complexes was investigated.

RESULTS

Fragmented QRS frequency was significantly higher in patients with OSAS (n = 31 [61%] vs. n = 12 [35%], P = 0.021). QRS and QTc durations were also significantly longer in OSAS patients than controls (99.8 ± 13.9 ms vs. 84.7 ± 14.3 ms, P < 0.001; 411.4 ± 26.9 ms vs. 390.1 ± 32.2 ms, P = 0.001, respectively). Analysis of the patient and controls groups combined revealed a weak-moderate correlation between AHI and QRS duration (r = 0.292, P = 0.070). OSAS group had no correlation between AHI and QRS duration (r = -0.231, P = 0.203).

CONCLUSIONS

In our study fragmented QRS frequency and QRS duration were found to increase in OSAS patients. Both parameters are related with increased cardiovascular mortality. Considering the prognostic importance of ECG parameters, it may be reasonable to recommend more detailed evaluation of OSAS patients with fragmented or prolonged QRS complexes with respect to presence of cardiovascular diseases.

Electrocardiogram characteristics prior to in-hospital cardiac arrest

Survival after in-hospital cardiac arrest (I-HCA) remains < 30 %. There is very limited literature exploring the electrocardiogram changes prior to I-HCA. The purpose of the study was to determine demographics and electrocardiographic predictors prior to I-HCA. A retrospective study was conducted among 39 cardiovascular subjects who had cardiopulmonary resuscitation from I-HCA with initial rhythms of pulseless electrical activity (PEA) and asystole. Demographics including medical history, ejection fraction, laboratory values, and medications were examined. Electrocardiogram (ECG) parameters from telemetry were studied to identify changes in heart rate, QRS duration and morphology, and time of occurrence and location of ST segment changes prior to I-HCA. Increased age was significantly associated with failure to survive to discharge (p < 0.05). Significant change was observed in heart rate including a downtrend of heart rate within 15 min prior to I-HCA (p < 0.05). There was a significant difference in heart rate and QRS duration during the last hour prior to I-HCA compared to the previous hours (p < 0.05). Inferior ECG leads showed the most significant changes in QRS morphology and ST segments prior to I-HCA (p < 0.05). Subjects with an initial rhythm of asystole demonstrated significantly greater ECG changes including QRS morphology and ST segment changes compared to the subjects with initial rhythms of PEA (p < 0.05). Diagnostic ECG trends can be identified prior to I-HCA due to PEA and asystole and can be further utilized for training a predictive machine learning model for I-HCA.

Correlation between fragmented QRS and the short-term prognosis of patients with acute myocardial infarction

This study is aimed to investigate the clinical significance and the short-term prognostic value of fragmented QRS (fQRS) for patients with acute myocardial infarction (AMI). Three hundred patients with AMI were tested with retrospective analysis on the patients' clinical information, hospitalized treatment, fQRS onset time, location of lesions, and other relevant data, in order to assess the relationship between the presence of fQRS and its prognosis. The rates of malignant cardiac arrhythmia, left ventricular systolic dysfunction (LVSD), and mortality in the positive fQRS group were 13.6%, 29.2%, and 23.7%, respectively, with all showing a p value <0.05. For the ST segment elevation myocardial infarction (STEMI) subgroup, all the rates showed significant differences with a p value <0.01, while for the non-STEMI (NSTEMI) subgroup showed no significant differences. In patients with a positive fQRS, there were no differences in malignant cardiac arrhythmia between patients with and without percutaneous coronary intervention (PCI) (p>0.05). As for the LVSD and mortality, the p values between patients with and without PCI were 0.031 and 0.000, respectively, suggesting statistical significance. The results imply that AMI patients with positive fQRS especially for the patients with STEMI had higher rates of malignant cardiac arrhythmia, LVSD, and mortality than the non-fQRS group. Patients of AMI with positive fQRS, who underwent early revascularization, could lower the incidence of the cardiovascular event. In addition, the presence of fQRS could be used as an indication of early intervention treatment for patients.

Non-invasive evaluation of arrhythmic risk in dilated cardiomyopathy: From imaging to electrocardiographic measures

Malignant ventricular arrhythmias are a major adverse event and worsen the prognosis of patients affected by ischemic and non-ischemic dilated cardiomyopathy. The main parameter currently used to stratify arrhythmic risk and guide decision making towards the implantation of a cardioverter defibrillator is the evaluation of the left ventricular ejection fraction. However, this strategy is characterized by several limitations and consequently additional parameters have been suggested in order to improve arrhythmic risk stratification. The aim of this review is to critically revise the prognostic significance of non-invasive diagnostic tools in order to better stratify the arrhythmic risk prognosis of dilated cardiomyopathy patients.

Fragmented QRS complexes-a novel but underutilized electrocardiograhic marker of heart disease

The electrocardiogram is the mainstay approach for diagnosing a myocardial infarction (MI). The diagnosis of an old MI and the identification of myocardial scar via the electrocardiogram are difficult because there are no other specific signs for a non-Q-wave MI. In this article, we will review the fragmented QRS and its role in identifying myocardial scar and depolarization abnormalities in patients with coronary artery disease.

Predictive value of a fragmented QRS complex in patients undergoing primary angioplasty for ST elevation myocardial infarction

OBJECTIVES

The aim of this study was to evaluate the prognostic value of fragmented QRS (fQRS) on electrocardiography (ECG) patients with acute ST-segment elevation in myocardial infarction (STEMI), who are undergoing primary percutaneous coronary intervention (PCI).

METHODS

We prospectively enrolled 414 consecutive STEMI patients (mean age of 55.2 ± 12.2 years old, range of 26-91-years old) undergoing primary PCI. The study patients were divided into two groups according to the presence or absence of fQRS as shown by ECG in the first 48 hours. The presence of fQRS group was defined as fQRS(+) (n = 91), and the absence of fQRS group was defined as the fQRS(-) (n = 323) group. Clinical characteristics and the one-year outcome of the primary PCI were analyzed.

RESULTS

The patients in the fQRS(+) group were older (mean age 60.7 ± 12.5 vs. 53.6 ± 11.6 years old, P < 0.001). Higher one-year all-cause mortality rates were observed in the fQRS group upon ECG (23.1% vs. 2.5%, P < 0.001, respectively). When using the Cox multivariate analysis, the presence of fQRS on the ECG was found to be a powerful independent predictor of one-year all-cause mortality (hazard ratio: 5.24, 95% confidence interval: 1.43-19.2, P = 0.01).

CONCLUSIONS

These results suggest that the presence of fQRS on ECG was associated with an increased in-hospital cardiovascular mortality, and one-year all-cause mortality in patients with STEMI who are under primary PCI.

The relationship between fragmentation on electrocardiography and in-hospital prognosis of patients with acute myocardial infarction

Background

In patients with acute ST elevation myocardial infarction (STEMI), QRS fragmentation was determined as one of the indicators of mortality and morbidity. The development of fragmented QRS (fQRS) is related to defects in the ventricular conduction system and is linked to myocardial scar and fibrosis.

Material/Methods

We prospectively enrolled 355 consecutive patients hospitalized in the coronary intensive care unit of our hospital with STEMI between the years 2010 and 2012 and their electrocardiographic features and the frequency of in-hospital cardiac events were evaluated.

Results

There were 217 cases in the fQRS group and 118 cases in the control group. QRS fragmentation was found to be a predictor for major cardiac events. In the fragmented QRS group, the frequency of in-hospital major cardiac events (MACE) and death were higher (MACE p<0.001; death p<0.003). In the fragmented QRS group, the cardiac enzymes (Troponin-I, CK-MB) were significantly higher than in the control group (p<0.001). In subgroup analyses, apart from the presence of fragmentation, the presence of more than 1 type of fragmentation and the number of fragmented deviations were also found to be related with MACE. A significant negative correlation was observed with the ejection fraction and, in particular, the number of fragmented deviations.

Conclusions

Fragmented QRS has emerged as a practical and easily identifiable diagnostic tool for predicting in-hospital cardiac events in acute coronary syndromes. Patients who present with a fragmented QRS demonstrate increased rates of major cardiac events, death risk, and low ejection fraction. In patients with STEMI, the presence of fQRS on the ECG and number of fQRS derivations are a significant predictor of in-hospital major cardiac events.

Increased frequency of fragmented QRS in patients with severe aortic valve stenosis

OBJECTIVE

To investigate the presence of myocardial fibrosis determined by fragmented QRS in patients with severe aortic valve stenosis.

SUBJECTS AND METHODS

Eighty-seven consecutive patients with severe aortic valve stenosis and 83 age- and gender-matched control subjects were enrolled into this study. Severe aortic valve stenosis was defined as an aortic valve area <1 cm(2), a Vmax >4 m/s, or a mean gradient ≥40 mm Hg. Fragmented QRS was assessed using a 12-lead electrocardiogram.

RESULTS

Fragmented QRS was detected in 40 (46%) patients in the aortic valve stenosis group and in 15 (18%) control subjects (p < 0.001). In multivariate binary logistic regression analysis, the presence of aortic valve stenosis was the only independent factor associated with fragmented QRS (OR = 3.69; 95% CI 1.81-7.55, p < 0.001).

CONCLUSION

A higher frequency of fragmented QRS was detected in patients with severe aortic valve stenosis compared to controls.

J wave syndromes: molecular and cellular mechanisms

An early repolarization (ER) pattern in the ECG, consisting of J point elevation, distinct J wave with or without ST segment elevation or slurring of the terminal part of the QRS, was long considered a benign electrocardiographic manifestation. Experimental studies a dozen years ago suggested that an ER is not always benign, but may be associated with malignant arrhythmias. Validation of this hypothesis derives from recent case-control and population-based studies showing that an ER pattern in inferior or infero-lateral leads is associated with increased risk for life-threatening arrhythmias, termed early repolarization syndrome (ERS). Because accentuated J waves characterize both Brugada syndrome (BrS) and ERS, these syndromes have been grouped under the heading of J wave syndromes. BrS and ERS appear to share common ECG characteristics, clinical outcomes, risk factors as well as a common arrhythmic platform related to amplification of Ito-mediated J waves. However, they differ with respect to the magnitude and lead location of abnormal J waves and can be considered to represent a continuous spectrum of phenotypic expression. Recent studies support the hypothesis that BrS and ERS are caused by a preferential accentuation of the AP notch in right or left ventricular epicardium, respectively, and that this repolarization defect is accentuated by cholinergic agonists. Quinidine, cilostazol and isoproterenol exert ameliorative effects by reversing these repolarization abnormalities. Identifying subjects truly at risk is the challenge ahead. Our goal here is to review the clinical and genetic aspects as well as the cellular and molecular mechanisms underlying the J wave syndromes.

Fragmented surface ECG was a poor predictor of appropriate therapies in patients with Chagas' cardiomyopathy and ICD implantation (Fragmented ECG in CHAgas' Cardiomyopathy Study)

BACKGROUND

Main causes of death in chronic Chagas' cardiomyopathy (CChC) are progressive congestive heart failure and sudden cardiac death. Implantable cardioverter defibrillators (ICD) have been proved an effective therapy to prevent sudden death in patients with CChC. Identification of predictors of sudden death remains a challenge.

OBJECTIVE

To determine whether surface fragmented ECG (fQRS) helps identifying patients with CChC and ICDs at higher risk of presenting appropriate ICD therapies.

METHODS

Multicenter retrospective study. All patients with CChC and ICDs were analyzed. Clinical demographics, surface ECG, and ICD therapies were collected.

RESULTS

A total of 98 patients were analyzed. Another four cases were excluded due to pacing dependency. Mean age was 55.5 ± 10.4 years, male gender 65%, heart failure New York Heart Association class I 47% and II 38%. Mean left ventricular ejection fraction (LVEF) 39.6 ± 11.8%. The indication for ICD was secondary prevention in 70% of patients. fQRS was found in 56 patients (59.6%). Location of fragmentation was inferior (57.1%), lateral (35.7%), and anterior (44.6%). Rsr pattern was the more prevalent (57.1%). Predictors of appropriate therapy in the multivariate model were: increased age (P = 0.01), secondary prevention indication (P = 0.01), ventricular pacing >50% of the time (P = 0.004), and LVEF <30% (P = 0.01). The presence of fQRS did not identify patients at higher risk of presenting appropriate therapies delivered by the ICD (P = 0.87); regardless of QRS interval duration.

CONCLUSIONS

fQRS is highly prevalent among patients with CChC. It has been found a poor predictor of appropriate therapies delivered by the ICD in this population.

Comparison of fragmented QRS and myocardial perfusion-gated SPECT findings

AIM

Fragmented QRS (fQRS) complex is an ECG parameter that has recently been introduced and investigated. It is assumed that fQRS occurs because of disruptions in ventricular conduction due to ventricular infarction and ischemia. Therefore, in this article, we aimed to investigate the relationship between the detection of infarction and ischemia on myocardial perfusion-gated single-photon emission computed tomography images and appearance of fQRS on ECG.

MATERIALS AND METHODS

We retrospectively reviewed the records of patients with a diagnosis of coronary artery disease who were referred to our institution for myocardial perfusion scintigraphy. In total, 261 patients (122 women and 139 men, with a mean age of 61±10.33 years) with and without fQRS (136 and 125, respectively) were included in the present study. The myocardial perfusion scintigraphy results were evaluated for the presence or absence of myocardial ischemia and infarction by visual and quantitative (summed stress score, summed rest, summed difference score, summed motion score, and summed thickening score) assessments. Statistical analysis was performed to determine the relationship between the presence of fQRS and myocardial ischemia and/or infarction. Student's t-test and the Mann-Whitney U-test were used for comparing the results. Pearson's χ2-test and Fisher's exact tests were also used to compare the distribution of variables between the two groups.

RESULTS

The prevalence of ischemia and infarction were found to be, respectively, 4.38-fold and 5.95-fold higher in patients with fQRS compared with the control group. Moreover, the prevalence of both ischemia and infarction was found to be 10.54-fold higher in patients with fQRS compared with the control group.

CONCLUSION

There is a highly statistically significant possibility of detecting ischemia and infarction in perfusion myocardial scintigrams of patients whose ECGs have fQRS.