Electrocardiographic changes associated with patchy myocardial fibrosis in the absence of confluent myocardial infarction; an anatomic correlative study

Novel Approaches in Cardiac Imaging for Non-invasive Assessment of Left Heart Myocardial Fibrosis

In the past, the identification of myocardial fibrosis was only possible through invasive histologic assessment. Although endomyocardial biopsy remains the gold standard, recent advances in cardiac imaging techniques have enabled non-invasive tissue characterization of the myocardium, which has also provided valuable insights into specific disease processes. The diagnostic accuracy, incremental yield and prognostic value of speckle tracking echocardiography, late gadolinium enhancement and parametric mapping modules by cardiac magnetic resonance and cardiac computed tomography have been validated against tissue samples and tested in broad patient populations, overall providing relevant clinical information to the cardiologist. This review describes the patterns of left ventricular and left atrial fibrosis, and their characterization by advanced echocardiography, cardiac magnetic resonance and cardiac computed tomography, allowing for clinical applications in sudden cardiac death and management of atrial fibrillation.

Fragmented QRS complex is an independent predictor of plaque burden in patients at intermediate risk of coronary artery disease

OBJECTIVE

We aimed to evaluate the relationship between fragmented QRS complex and plaque burden in patients presented with typical chest pain and deemed to have intermediate pretest probability of CAD using coronary computed tomography angiography (CCTA).

METHODS

We studied electrocardiograms (ECGs) obtained from 172 subjects (47.5 ± 9.5 years, 125 were men) presented with chest pain and had intermediate pretest probability for CAD. The presence was found and evaluation of CAD was performed with CCTA.

RESULTS

Seventy four (43%) of the study cohort had CCTA-documented CAD. Meanwhile the frequency of fQRS in our cohort was (57%). 70 (71.4%) patients with fQRS had CAD compared with only 4 (5.4%) patients without fQRS (p < 0.001). The number of leads with fQRs was correlated with the calcium score (p < 0.005), segment stenosis score, segment involvement score, total plaque score (TPS), and E/e ratio (p < 0.001, for all). Multivariate analysis demonstrated that fQRS was a strong independent predictor for CAD (or = 2.15, p < 0.001). ROC analysis showed that the number of leads ≥3 was the optimal number for predicting CAD (AUC = 0.89, sensitivity 88%, and specificity 83%, p < 0.001).

CONCLUSION

Fragmented QRS was seen more often in patients with high plaque burden. We suggest that fQRS might provide a useful noninvasive prognosticator for subjects with intermediate pretest probability of CAD for further investigation.

Frequency content and characteristics of ventricular conduction

The spectrum of frequencies producing the QRS complex has not been fully explored. In this manuscript we review previous studies of QRS frequency content, and discuss our novel method of the conjoint analysis of the ECG signal in six dimensions: in the domain of three space dimensions, in time domain, and in frequency domain. Orbital frequency of QRS loop is introduced as a six-dimensional characteristic of ventricular conduction, which helped to reveal inapparent ventricular conduction, and to characterize electrophysiological substrate. In this paper, we review our novel method in the historical context.

Significance of a fragmented QRS complex in patients with chronic total occlusion of coronary artery without prior myocardial infarction

Objective:

Fragmented QRS (fQRS) complexes that have numerous RSR´ patterns represent alteration of ventricular depolarization. We evaluated the relationship between fQRS and poor coronary collateral circulation and the diagnostic ability of fQRS for myocardial scar detection in patients with chronic total occlusion (CTO) without a history of myocardial infarction.

Methods:

The study population consisted of patients undergoing coronary angiography with a suspicion of CAD. Seventy-nine patients with one totally occluded major coronary artery were enrolled. Exclusion criteria were history of MI; recent acute coronary syndrome; pathologic Q wave on 12-lead ECG; cardiomyopathy or severe valvular disease; coronary artery bypass surgery or percutaneous coronary angioplasty. Collateral circulation was scored on the basis of Rentrop's classification. All patients were assessed by myocardial perfusion SPECT. Fragmented QRS was characterized as existence of an R´ or R wave or S wave notch in two adjacent leads related to the location of a major coronary artery region. Single and multiple logistic regression analyses were completed in the forward method.

Results:

Forty-nine patients had poor and 30 had well-developed collateral circulation. Fragmented QRS complexes were significantly higher in the poor collateral group (81% vs. 20%, p<0.001). Sensitivity, specificity, and the positive and negative predictive values of fQRS for myocardial scar identification were 89.4%, 87.5%, and 91.3% and 84.8%, respectively. The summed stress score and the summed rest score on SPECT were significantly higher in the poor collateral group than in the well-developed group (p<0.001) as well as in the fQRS group than the non-fQRS group (p<0.001). Logistic regression analysis revealed that the presence of fQRS was significantly and independently associated with poor collateral circulation and myocardial scar in patients with CTO.

Conclusion:

Fragmented QRS is independently related to poor coronary collateral circulation in patients with CTO without prior myocardial infarction. Notably, it can be a good predictor of myocardial scar rather than merely ischemia, with high diagnostic accuracy.

Fragmented QRS can predict severity of aortic stenosis

BACKGROUND

Fragmented QRS (fQRS) is an indicator of nonhomogeneous ventricular activity caused by myocardial fibrosis. Aortic stenosis (AS) is known to be a cause of myocardial fibrosis. We aimed to investigate the relationship of fQRS with severity of AS, echocardiographic, and electrocardiographic findings, and development of atrial fibrillation and manifest heart failure in AS patients.

METHODS

One hundred four patients with moderate and severe AS were recruited for the study. Patients with mitral or tricuspid stenosis, previous myocardial infarction, segmental wall motion abnormality or left ventricular ejection fraction (LVEF) below 50% and patients with complete-incomplete BBB and pacemaker rhythm were excluded.

RESULTS

Mean age of the patients was 69 ± 14.8 and 73.1% had fQRS. Patients with fQRS had lower LVEF, higher mean QRS duration, intrinsic deflection, Cornell voltage, Romhilt-Estes Score, systolic pulmonary artery pressure, mean and peak systolic transaortic gradients and left atrium diameter. Manifest heart failure was more frequent in patients with fQRS. In stepwise multivariate logistic regression analyze, manifest heart failure, peak systolic transaortic gradient, LVEF, intrinsic deflection, strain pattern and Cornell voltage were independently associated with fQRS. Strain pattern and fQRS were found as independent predictors of severe AS.

CONCLUSIONS

fQRS is independently associated with the severity of AS while traditional LVH criteria, except strain pattern, are not. fQRS may be better than traditional ECG criteria of LVH and echocardiographic LVH as an indicator of myocardial fibrosis in AS. Thus, fQRS may have a role in determining the severity and prognosis of AS.

Absence and Resolution of Fragmented QRS Predict Reversible Myocardial Ischemia With Higher Probability of ST Segment Resolution in Patients With ST Segment Elevation Myocardial Infarction

BACKGROUND AND OBJECTIVES

Fragmented QRS complexes (fQRS) are associated with increased morbidity and mortality. The causative relationship between fQRS and cardiac fibrosis has been shown, but whether the presence and the number of fQRS on admission of electrocardiogram (ECG) predicts ST segment resolution in patients undergoing primary percutaneous coronary intervention (p-PCI) has not been investigated until now.

SUBJECTS AND METHODS

This study included one hundred and eighty-four consecutive patients with ST elevation myocardial infarction (STEMI) who underwent p-PCI. The presence or absence of fQRS on pre and post-PCI ECG and their relation with myocardial infarction and reperfusion parameters were investigated.

RESULTS

Patients with fQRS on admission of ECG or newly developed fQRS after p-PCI had increased inflammatory markers, higher cardiac enzyme levels, increased pain to balloon time, prolonged QRS time, more extended coronary involvement and more frequent Q waves on ECG in comparison to patients with absence or resolved fQRS. The presence and higher number of fQRS on admission or post-PCI ECGs were significantly related with low percent of ST resolution and myocardial reperfusion parameters. The area under the receiver operating characteristics curve values for the presence and number of fQRS to detect Thrombolysis in Myocardial Infarction Blush Grade 0 and 1, were 0.682 and 0.703.

CONCLUSION

In our study, fQRS was significantly related to infarction and myocardial reperfusion parameters before and after p-PCI. Successful myocardial reperfusion by p-PCI caused the reduction in number of fQRS and QRS time with higher ST resolution. fQRS may be useful in identifying the patients at higher cardiac risk with increased ischemic jeopardized or infarcted myocardium, and persistent or newly developed fQRS may predict low percent of ST segment resolution in patients undergoing p-PCI.

The independent relationship of systemic inflammation with fragmented QRS complexes in patients with acute coronary syndromes

Background and Objectives

QRS complex fragmentations are frequently seen on routine electrocardiograms with narrow or wide QRS complex. Fragmented QRS complex (fQRS) is associated with increased morbidity and mortality, sudden cardiac death and recurrent cardiovascular events. In this study, we aimed to interrogate the relationship of systemic inflammation with the presence of fQRS in patients with acute coronary syndromes (ACS).

Subjects and Methods

Two-hundred and twenty eligible patients with ACS that underwent coronary angiography were enrolled consecutively in this study. Patients with significant organic valve disease and those with any QRS morphology that had a QRS duration ≥120 ms as well as patients with permanent pacemakers were excluded from this study.

Results

Patients with fQRS were of a higher age (p=0.02), had increased C-reactive protein (CRP) levels (p<0.001), prolonged QRS time (p<0.001), extent of coronary artery disease (CAD) (p<0.001), creatine kinase-MB (CK-MB) levels (p=0.006) and Q wave on admission electrocardiography (p<0.001) in comparison to patients with non-fragmented QRS. When we performed multiple logistic regression analysis, fQRS was found to be related to increased CRP levels {odds ratio (OR): 1.2, 95% confidence interval (CI): 1.045-1.316, p=0.007}, QRS duration (OR: 1.1, 95% CI: 1.033-1.098, p<0.001), extent of CAD (OR: 1.5, 95% CI: 1.023-2.144, p=0.037), Q wave (OR: 2.2, 95% CI: 1.084-4.598, p=0.03) and CK-MB levels (OR: 1.0, 95% CI: 1.001-1.037, p=0.04) independently.

Conclusion

In our study, we found that fQRS was independently related to increased CRP. Fragmented QRS that may result as an end effect of inflammation at cellular level can represent increased cardiac risk by different causative mechanisms in patients with ACS.

Relationship of fragmented QRS complexes with inadequate coronary collaterals in patients with chronic total occlusion

BACKGROUND

Fragmented QRS (fQRS) complexes are defined as various RSR' patterns (≥1 R' or notching of S wave or R wave) in two contiguous leads corresponding to a major coronary artery territory. In previous studies, fQRS has been associated with increased morbidity and mortality, sudden cardiac death and recurrent cardiovascular events (CVEs). The causative relationship between fQRS and cardiac fibrosis has been shown in prior studies. The association between inadequate (poor) coronary collaterals and presence of fQRS has not comprehensively been studied in patients with chronic total occlusion (CTO) until now. We tested the hypothesis that the presence of fQRS is associated with inadequate coronary collateral growth.

METHODS

This study had a cross-sectional observational design. The study population consisted of patients who underwent coronary angiography with the suspicion of coronary artery disease at our institution in an outpatient manner. Patients who had CTO in at least one major epicardial coronary artery were included. Coronary angiograms of 148 eligible patients from our database were analyzed again. Ninety-three patients had good and 55 had poor collateral development according to the Cohen-Rentrop method.

RESULTS

Patients with poor collateral development had higher plasma glucose (130 ± 54 vs. 116 ± 33 mg/dl, P = 0.047) and an older age (65 ± 10 vs. 61 ± 10  years, P = 0.042) in comparison to patients with good collateral growth. The presence and number of fQRS were higher in the poor collateral group than the good collateral group (64 vs. 32%, P < 0.001 and 2.3 ± 2.4 vs. 1.2 ± 2.0, P = 0.002, respectively). Left ventricular ejection fraction was significantly lower in the poor collateral group than the good collateral group (45 ± 11 vs. 51 ± 13, P = 0.014). There was a significant correlation between number of fQRSs and the echocardiographic wall-motion abnormality score (r = 0.662, P < 0.001). In multivariate analysis, only the presence of fQRS was independently related to poor collateral development (odds ratio, 3.559; 95% confidence interval, 1.708-7.415, P = 0.001).

CONCLUSION

We found that fQRS was independently related to inadequate coronary collaterals in patients with CTO. fQRS, which may be derived from the effects of myocardial ischemia or scar on myocardial electricity at the cellular level, can represent inadequate coronary collateral development in patients with CTO.

Relationship of fragmented QRS with prognostic markers and in-hospital MACE in patients undergoing CABG

BACKGROUND

Fragmented QRS complex (fQRS) is associated with increased morbidity and mortality, sudden cardiac death and recurrent cardiovascular events. However, its prognostic role has not been studied comprehensively in patients undergoing coronary artery bypass graft (CABG) surgery. In this study, we investigated the relationship between the presence of fQRS, and the prognostic markers and in-hospital major adverse cardiovascular events (MACE).

METHODS

Two hundred and forty two eligible patients who underwent CABG surgery at our institution were enrolled consecutively. In analysis of fragmentations on electrocardiograms, presence of fQRS was defined as various RSR' patterns (≥ 1 R' or notching of S wave or R wave) with or without Q waves without a typical bundle-branch block in two contiguous leads corresponding to a major coronary artery territory. MACE was defined as cardiac death, recurrent myocardial infarction, heart failure, cerebrovascular event, sustained ventricular tachycardia or fibrillation.

RESULTS

Patients with fragmented QRS had older age (64 ± 10 vs. 61 ± 9 years, p = 0.03), prolonged QRS time (99 ± 11 vs. 87 ± 11 ms, p < 0.001), higher rate of Q wave on ECG (29% vs. 12%, p = 0.001), higher European system for cardiac operative risk evaluation (EUROSCORE) (4.0 ± 1.9 vs. 2.6 ± 1.6, p < 0.001) and lower left ventricular ejection fraction (LVEF)% (43 ± 12 vs. 60 ± 12, p < 0.001) in comparison to patients with non-fragmented QRS. In addition, the patients with fQRS had longer cross-clamp time (67 ± 23 vs. 55 ± 20 minutes, p = 0.001) and extracorporeal circulation (105 ± 31 vs. 91 ± 30 minutes, p = 0.003), increased inotropic usage (p < 0.001) and prolonged cardiac surgery intensive care unit (53 ± 25 vs. 35 ± 12 hours, p < 0.001) and in-hospital stay after CABG.

CONCLUSION

FQRS may have additional value in the assessment of cardiac function and in prediction of intra- and post-operative hemodynamic instability and adverse cardiovascular events. Fragmentations on admission ECG may be useful for identifying patients with higher risk who will need additional support after CABG surgery.

The prognostic significance of horizontal plane QRS axis in elderly heart failure

In order to investigate whether horizontal plane QRS axis predicts the prognosis in elderly heart failure, we studied 80 consecutive patients by clinical assessment, ECG, Doppler and echocardiography. All patients were followed up for 2 years, 12 died and 68 survived. Age, gender distribution, blood pressure, co-existing diagnoses and medication were all similar between those who died and those who survived. The NYHA classification was significantly worse, left ventricular (LV) cavity size was greater, LV systolic function was lower in those who died than in survivors, despite similar LV wall thickness. On ECG, heart rate, PR interval, QT interval and frontal QRS axis did not differ between the two groups. The QRS duration was significantly longer and the horizontal QRS axis projected to a substantially more posterior direction in those who died than in survivors. The sensitivity and specificity of a horizontal QRS axis < or =-30 degrees for predicting death in 2 years were 75% and 62%, respectively. The former is above the sensitivity of a NYHA > or =3 and the latter is above the specificity of a LV shortening fraction < or =20%. The combination of a QRS horizontal axis < or =-30 degrees and NYHA > or =3 predicted 2 year mortality with a sensitivity of 75% and specificity of 91%. In conclusion, a left posterior QRS axis of the horizontal plane in elderly heart failure indicates an adverse prognosis, particularly when combined with NYHA classification and echocardiographic assessment.

ELECTROCARDIOGRAPHIC "PERI-INFARCTION BLOCK". A CLINICAL AND PATHOLOGIC CORRELATION

Detailed analysis for the presence and type of heart disease was made in 96 deceased patients who had electrocardiographic "peri-infarction block." Evidence for disease of the left ventricle was found in 80 per cent of these patients. Left ventricular hypertrophy and diffuse scarring of the left ventricle were the most common abnormalities on pathologic examination. Definite myocardial infarction was found in only 12 of the 55 patients (22 per cent) subjected to postmortem examination. Electrocardiographic "peri-infarction block" was therefore not specific for myocardial infarction although it was often associated with it. Use of the term should be restricted to left intraventricular conduction defect of the "peri-infarction block type."

In spite of the nonspecificity of this type of intraventricular conduction defect, it can be a useful clinical sign. If chronic obstructive airway disease and emphysema can be excluded, the presence of some type of left ventricular disease is almost assured.

Importance of notching and slurring of the resting QRS complex in the diagnosis of coronary artery disease

Data on the correlation of coronary artery disease (CAD) and electrocardiographic findings are, except for Q waves, still controversial. The purpose of this study was to determine whether QRS complex notching and slurring (N&S) is of significant value as a diagnostic discriminator in the detection of CAD. This study comprised 500 consecutive patients aged between 24 and 81 years (mean, 53.4 years) who underwent coronary angiography because of chest pain. Patients were evaluated for CAD, angiographic evidence of myocardial infarction (MI), N&S, and abnormal Q waves. Of these 500 patients, 418 had CAD, and 370 of these had significant (> or = 70%) coronary artery obstruction. The remaining 82 patients had normal coronary arteries. The data revealed that the distribution of N&S in the patients with or without CAD was similar in both the inferior and limb leads (P > .05). But the percentage of N&S in more than two contiguous limb leads was higher in the patients with CAD than in the patients without CAD. Notching and slurring in at least one limb lead was found to be of no value in the diagnosis of MI, of wall motion abnormalities, and of significant obstruction. Notching and slurring in the anterior leads is more sensitive but less specific than abnormal Q waves in the same leads in the detection of significant obstruction, anterior MI, and anterior wall motion abnormalities. Notching and slurring in the anterior leads has as much importance as abnormal anterior Q waves in the detection of angiographic evidence of anterior infarct, of anterior wall motion abnormalities, and of significant coronary artery obstruction.(ABSTRACT TRUNCATED AT 250 WORDS)

Clinical significance of terminal QRS abnormalities in the setting of inferior myocardial infarction

To ascertain the clinical relevance of terminal electrocardiographic (ECG) QRS prolongation in the setting of inferior myocardial infarction, 32 patients were studied by radionuclide ventriculography to evaluate regional left ventricular contractility. Of the 32 patients, 16 had evidence of terminal QRS prolongation and notching associated with inferior myocardial infarction, and 16 had isolated ECG evidence of inferior myocardial infarction without terminal QRS prolongation. The regional ejection fraction in the posterolateral and inferoapical regions of patients with terminal conduction delay was lower than those without this conduction delay. This group also demonstrated a lower global ejection fraction than those patients with ECG evidence of inferior myocardial infarction without terminal QRS changes. Terminal QRS abnormalities are important qualitative predictors of left ventricular dysfunction in the setting of inferior myocardial infarction.

Value of notching and slurring of the resting QRS complex in the detection of ischemic heart disease

The resting 12-lead ECG has long been known to be an insensitive marker of underlying ischemic heart disease (IHD). The purpose of this study was to determine if QRS complex notching and slurring is of significant value as a diagnostic discriminator in the detection of IHD. The data from 205 consecutive patients coming to cardiac catheterization for evaluation of probable IHD were initially analyzed. Eighty-three patients were excluded based upon ventricular hypertrophy, bundle-branch block, lack of data, and pacemaker rhythm. The balance, 122 patients (mean age 61.7 years), were evaluated for angiographic evidence of IHD, ECG findings of QRS notching or slurring, and abnormal Q waves. The data revealed a high prevalence of QRS notching or slurring; 62.2% in those patients with IHD, double the prevalence of significant Q waves (33.3%). The two markers had an approximately equal prevalence (QRS notching or slurring 61.7% vs. Q waves 53.2%) in patients with angiographic evidence of infarction; however, in patients with less than infarct criteria for IHD, the prevalence of QRS notching or slurring was 62.8%, while only 11.6% showed abnormal Q waves. Analysis indicated that QRS notching or slurring has a sensitivity of 62.2% and a specificity of 93.8% for the detection of IHD. The study demonstrates that QRS notching or slurring is a moderately sensitive and a very specific marker of ischemic heart disease in selected patients when using the resting ECG, and is of greatest value in those patients with lesser degrees of ischemic myocardial injury where the prevalence of Q waves is low.

Left ventricular parietal block: diagnostic and clinical study

Fifty-five patients with widened QRS complexes due to the presence of slurred S waves or of terminal slurrings on R waves, in more than three leads, with no infarction or bundle branch and fascicular blocks, were studied with the usual clinical examinations as well as vectorcardiographic recording. A parietal block of the left ventricle was diagnosed when, in the presence of a normal development of ventricular depolarization in the initial and middle phases, the terminal QRS loop was delayed, sometimes irregular and displaced leftward and posteriorly. When this delay was directed to the right, the ventricular localization was puzzling. The comparison of the electrocardiographic (ECG) and vectorcardiographic (VCG) data on the terminal part of ventricular depolarization showed some discrepancies and revealed the greater importance of VCG investigation for the study and the localization of parietal blocks. The pathogenesis of such minor conduction disturbances is not yet clear, since the experimental data on the anatomical-functional structures are different: the Purkinje network, Purkinje fiber-muscle junction or common myocardium. In some cases we think it is possible to localize the structure concerned; in any case we can always localize it at the level of the free ventricular wall.

Characteristics of the Frequency Spectrum in the Normal Electrocardiogram and in Subjects Following Myocardial Infarction

The results of a study of the sealar electrocardiogram, utilizing a wide-band recorder, expanded time scale and a low-pass filter, indicate that a recorder flat to at least 500 c.p.s. is required for faithful reproduction. With a high-pass filter, measurable residual signals are present at a cut-off frequency of 1,000 c.p.s., or higher. Therefore, to record these, an adequate response at 1,000 c.p.s. or more is reqnired. The high frequency energy of the electrocardiographic spectrum arises from the fast deflections contained in the original waveform. These may occur in a single fast deflection, notching, or both. Whereas, in the normal individual, high frequency energy usually arises from a relatively smooth, fast deflection, in abnormals the fast events may occur in conjunction with notching, and other deformities. Judging from the technic used in this experiment, a variable band-pass filter is valuable as an aid for studying the high frequency components of the electrocardiogram and establishing equipment requirements. Measurement of peak-to-peak voltage of residual signals gives partial but lot clear-cut separation of normal and abnormal subjects and would not seem to add to the value of high-fidelity electrocardiography per se in routine clinical diagnosis. It is possible that root mean square readings, reflecting the total energy content, might give a better separation between normal and abnormal subjects than peak-to-peak amplitude alone.

Electrocardiograms of ninety patients with acrosclerosis and progressive diffuse sclerosis (scleroderma)

The records of all patients with scleroderma seen at the Mayo Clinic during the years 1949 through 1953 were reviewed. There were 90 who had electrocardiograms available for study. The diagnosis in 63 patients was acrosclerosis and 27 were diagnosed as having progressive diffuse sclerosis.

Electrocardiographic diagnosis of myocardial infarction in the presence of left bundle-branch block

It is generally accepted that most myocardial infarctions are obscured on the electrocardiogram by left bundle-branch block. The number of published cases in which this could be evaluated, however, is small, and the case reports are scattered. We have studied 30 cases of myocardial infarction with left bundle-branch block in which the location of the infarction could be determined with certainty, by autopsy, or by a previous electrocardiogram with normal intraventricular conduction. Twenty such published cases have also been collected. Electrocardiographic abnormalities have been correlated with infarctions in different locations. The possible specificity of these abnormalities is discussed.

The lesser electrocardiographic signs of cardiac pain

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