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

Fragmented QRS complex predicts contrast-induced nephropathy and in-hospital mortality after primary percutaneous coronary intervention in patients with ST-segment elevation myocardial infarction

BACKGROUND

Contrast-induced nephropathy (CIN) is associated with increased mortality after primary percutaneous coronary intervention (PCI) for ST-segment elevation myocardial infarction (STEMI). Recently, fragmented QRS complex (fQRS) on 12-lead electrocardiography has been introduced as a marker of cardiovascular disease and is associated with increased morbidity and mortality.

HYPOTHESIS

fQRS on ECG is associated with CIN and in-hospital mortality after primary PCI in patients with STEMI.

METHODS

Eight hundred ninety-five patients with first STEMI treated by primary PCI were enrolled in the study. Patients were divided into 2 groups according to the presence or absence of fQRS as shown by 12-lead electrocardiography in the first 24 hours. fQRS was defined by presence of an additional R wave (R″), or notching of the S wave, or >1 R' in 2 contiguous leads. Patients were then reallocated to 2 groups according to presence or absence of postprocedural CIN, which was defined as a rise in serum creatinine of 0.5 mg/dL or a 25% increase from baseline value within 72 hours after the procedure.

RESULTS

Patients with a fQRS were older and had significantly lower left ventricular ejection fraction. CIN occurred in 77 (8.6%) patients. The prevalence of CIN and in-hospital mortality was significantly higher in the fQRS(+) group. In multivariate analysis, fQRS was found to be an independent predictor of CIN (odds ratio: 3.125, P = 0.029) and in-hospital mortality (odds ratio: 9.062, P = 0.009).

CONCLUSIONS

The fQRS is an independent predictor of postprocedural CIN and in-hospital mortality in STEMI patients.

Early Repolarization Syndrome; Mechanistic Theories and Clinical Correlates

The early repolarization (ER) pattern on the 12-lead electrocardiogram is characterized by J point elevation in the inferior and/or lateral leads. The ER pattern is associated with an increased risk of ventricular arrhythmias and sudden cardiac death (SCD). Based on studies in animal models and genetic studies, it has been proposed that J point elevation in ER is a manifestation of augmented dispersion of repolarization which creates a substrate for ventricular arrhythmia. A competing theory regarding early repolarization syndrome (ERS) proposes that the syndrome arises as a consequence of abnormal depolarization. In recent years, multiple clinical studies have described the characteristics of ER patients with VF in more detail. The majority of these studies have provided evidence to support basic science observations. However, not all clinical observations correlate with basic science findings. This review will provide an overview of basic science and genetic research in ER and correlate basic science evidence with the clinical phenotype.

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.

Early repolarization and myocardial scar predict poorest prognosis in patients with coronary artery disease

PURPOSE

Recent studies show positive association of early repolarization (ER) with the risk of life-threatening arrhythmias in patients with coronary artery disease (CAD). This study was to investigate the relationships of ER with myocardial scarring and prognosis in patients with CAD.

MATERIALS AND METHODS

Of 570 consecutive CAD patients, patients with and without ER were assigned to ER group (n=139) and no ER group (n=431), respectively. Myocardial scar was evaluated using cardiac single-photon emission computed tomography.

RESULTS

ER group had previous history of myocardial infarction (33% vs. 15%, p<0.001) and lower left ventricular ejection fraction (57±13% vs. 62±13%, p<0.001) more frequently than no-ER group. While 74 (53%) patients in ER group had myocardial scar, only 121 (28%) patients had in no-ER group (p<0.001). During follow up, 9 (7%) and 4 (0.9%) patients had cardiac events in ER and no-ER group, respectively (p=0.001). All patients with cardiac events had ER in inferior leads and horizontal/descending ST-segment. Patients with both ER in inferior leads and horizontal/descending ST variant and scar had an increased adjusted hazard ratio of cardiac events (hazard ratio 16.0; 95% confidence interval: 4.1 to 55.8; p<0.001).

CONCLUSION

ER in inferior leads with a horizontal/descending ST variant was associated with increased risk of cardiac events. These findings suggest that ER in patients with CAD may be related to myocardial scar rather than pure ion channel problem.

Relationship between fragmented QRS and no-reflow, infarct size, and peri-infarct zone assessed using cardiac magnetic resonance in patients with myocardial infarction

BACKGROUND

The relation between fragmented QRS complex (fQRS) and cardiac magnetic resonance parameters is poorly documented in ischemic cardiopathy.

METHODS

Among 209 consecutive patients, those with fQRS were compared with those without fQRS. Cardiac magnetic resonance studies with late gadolinium-enhanced sequences were done during the week after acute myocardial infarction.

RESULTS

fQRS was present in 113 (54%) patients, and associated with a significantly lower left ventricular ejection fraction, increased left ventricular volumes, a larger infarct size (IS), and a larger peri-infarct zone. Microvascular obstruction was more frequent in patients with fQRS (62% vs 45%; P = 0.014) and the extent of the microvascular obstruction was significantly larger (1.6% [range, 0.0-4.4] vs 0.0 [range, 0.0-2.1]; P = 0.004). Finally, the transmurality score in the 2 study populations was identical (48% vs 47%; P = 0.895). In multivariate logistic regression analysis, only IS (odds ratio [OR], 1.06; 95% confidence interval [CI], 1.03-1.09; P < 0.001), systolic blood pressure (OR, 1.02; 95% CI, 1.01-1.04; P < 0.001), and left ventricular end-systolic volume (OR, 1.02; 95% CI, 1.00-1.03; P = 0.013) remained independent predictors of fQRS.

CONCLUSIONS

This study revealed that fQRS was associated with increased IS, myocardial perfusion abnormalities, decreased left ventricular ejection fraction, and increased left heart volumes. These findings show that fQRS is a reliable marker of infarct size and acute ventricular remodelling.

Prognostic value of fragmented QRS on a 12-lead ECG in patients with acute myocardial infarction

OBJECTIVE

To investigate the determinants and the prognostic value of fragmented QRS (fQRS) after AMI.

PATIENTS AND METHODS

Prospective cohort of 307 consecutive patients with AMI.

MAIN OUTCOMES MEASURED

MACE (death plus non-fatal recurrent MI), hospitalization for an episode of heart failure, ventricular arrhythmia (VT or VF) at two years follow-up.

RESULTS

On the serial 12-lead ECG recorded during the in-hospital stay, 162 (53%) had no fQRS (no fQRS group). 145 (47%) presented an fQRS, which was persistent in 108 (34%) patients (persistent fQRS group) and transient in 37 (12%) patients (transient fQRS group). Patients with a fragmented QRS (transient or persistent) were older, more likely to be hypertensive and less likely to be smokers than were patients without fQRS. By multivariate logistic regression analysis, only hypertension (OR (95% CI): 1.66 (1.00-2.74); p = 0.047) was associated with an fQRS. During a mean follow-up of 846 ± 297 days, there were 82 MACE recorded: 17 patients died from a CV cause (10% event rate) among patients without fQRS, 22 (20% event rate) among patients with persistent fQRS and 3 (8% event rate) among patients with transient fQRS. Similarly, non-fatal recurrent MI occurred more frequently in patients with fQRS (18 (16%) and 10 (27%)) for persistent and transient fQRS, respectively, vs. 16 (10%) in the no fQRS group (p = 0.019). However, the occurrence of heart failure symptoms and ventricular arrhythmia was not significantly different (p = 0.162 and p = 0.242, respectively). Survival analysis by the Kaplan-Meier method showed a significant difference (log rank p = 0.026) between groups, and only persistent fQRS was associated with decreased survival. In multivariate cox regression analysis, the GRACE score, blood glucose on admission, and B-blockers in the acute phase were independent predictors of MACE at two years. fQRS was not a significant independent predictor of MACE (HR (95% CI): 1.57 (0.95-2.60); p = 0.08). Moreover, fQRS was not a predictor of heart failure or ventricular arrhythmia in univariate analysis.

CONCLUSIONS

Persistent fQRS on a 12-lead ECG is a marker of decreased survival after AMI, whereas transient fQRS correlates with recurrent MI.

Long-term prognosis associated with J-point elevation in a large middle-aged biracial cohort: the ARIC study

AIMS

An association has been described between death from arrhythmia and early repolarization, an electrocardiogram pattern characterized by elevation of the QRS-ST junction (J-point). Little is known about this relationship in non-white populations. This study examines the relationship between J-point elevation (JPE) and sudden cardiac death (SCD) and whether this relationship differs by race or sex.

METHODS AND RESULTS

A total of 15 141 middle-aged subjects from the prospective, population-based Atherosclerosis Risk in Communities (ARIC) study were included in this analysis. The primary endpoint was physician-adjudicated SCD occurring from baseline (1987-1989) through December 2002, secondary endpoints were fatal and non-fatal coronary events and all-cause mortality occurring through December 2007. J-point elevation was defined as J-point amplitude ≥ 0.1 mV. Pre-specified subgroup analyses by sex and race were conducted. J-point elevation in any lead was present in 1866 subjects (12.3%). After adjustment for demographic, clinical, lifestyle, and laboratory variables, JPE was not significantly related to SCD in the overall sample [adjusted hazard ratio (HR), 1.23; 95% confidence interval (CI), 0.87-1.75]. However, significant interactions were present between race and JPE (P = 0.006) and between sex and JPE (P = 0.020). J-point elevation was significantly predictive of SCD in whites (adjusted HR, 2.03; 95% CI, 1.28-3.21) and in females (adjusted HR, 2.54; 95% CI, 1.34-4.82).

CONCLUSION

Our results suggest that JPE is associated with an increased risk of SCD in whites and in females, but not in blacks or males. Further studies are needed to clarify which subgroups of individuals with JPE are at increased risk for adverse cardiac events.

Early repolarization and markers of ventricular arrhythmogenesis in patients referred to ambulatory 24-hour ECG recording

BACKGROUND

Recent reports suggest that early repolarization, a common electrocardiographic (ECG) pattern that has been always considered benign, could be a substrate for ventricular arrhythmias and sudden cardiac arrest.

METHODS

We examined the associations between early repolarization and markers of ventricular arrhythmogenesis as defined by presence of ventricular late potentials (LPs) in the Signal Averaged ECG (SA-ECG), depressed heart rate variability (HRV) and/or presence of ventricular ectopy in patients referred to ambulatory 24-hour ECG recording (Holter).

RESULTS

This study included 687 patients (57% females) who were 51.2 ± 5.1 years. In unadjusted and multivariable adjusted analyses, early repolarization was not significantly associated with any of the measures of SA-ECG, HRV or ventricular ectopy. The lack of significant associations persisted in all subgroup analyses where different definitions of early repolarization in different groups of ECG leads were tested.

CONCLUSIONS

Early repolarization has no significant association with markers of ventricular arrhythmogenesis as detected by SA-ECG, HRV and ventricular ectopy. These findings suggest that the mechanisms of arrhythmic events in early repolarization (if they truly exist), are not likely to be through pathological pathways that could be detected by these markers.

Usefulness of fragmented QRS on a 12-lead electrocardiogram in acute coronary syndrome for predicting mortality

Electrocardiographic signs of a non-ST elevation myocardial infarction (NSTEMI) are nonspecific, and therefore the diagnosis of NSTEMI during acute coronary syndromes (ACS) depends mainly on cardiac biomarker levels. Fragmented QRS (fQRS) represents myocardial conduction abnormalities due to myocardial infarction (MI) scars in patients with coronary artery disease. However, the time of appearance of fQRS during ACS has not been investigated. It was postulated that in patients with ACS, fQRS on 12-lead electrocardiography occurs within 48 hours of presentation with NSTEMI as well as ST elevation MI and that fQRS predicts mortality. Serial electrocardiograms from 896 patients with ACS (mean age 62 +/- 11 years, 98% men) who underwent cardiac catheterization were studied. Four hundred forty-one patients had MIs, including 337 patients with NSTEMIs, and 455 patients had unstable angina (the control group). Serial electrocardiograms were obtained every 6 to 8 hours during the first 24 hours after the diagnosis of MI and the next day (<48 hours). Fragmented QRS on 12-lead electrocardiography was defined by the presence of single or multiple notches in the R or S wave, without a typical bundle branch block, in > or =2 contiguous leads in 1 of the major coronary artery territories. Fragmented QRS developed in 224 patients (51%) in the MI group and only 17 (3.7%) in the control group (p <0.001). New Q waves developed in 122 (28%), 76 (23%), and 2 (0.4%) patients in the MI, NSTEMI, and control groups, respectively. The sensitivity values of fQRS for ST elevation MI and NSTEMI were 55% and 50%, respectively. The specificity of fQRS was 96%. Kaplan-Meier survival analysis revealed that patients with fQRS had significantly decreased times to death compared to those without fQRS. Fragmented QRS, T-wave inversion, and ST depression were independent predictors of mortality during a mean follow-up period of 34 +/- 16 months. In conclusion, fQRS on 12-lead electrocardiography is a moderately sensitive but highly specific sign for ST elevation MI and NSTEMI. Fragmented QRS is an independent predictor of mortality in patients with ACS.

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.

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.

Left axis deviation. An electrocardiographic study with post-mortem correlation

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Recognition and significance of intraventricular block due to myocardial infarction (peri-infarction block)

Evidence of peri-infarction block was found in 39% of the electrocardiograms of 1,938 patients with definite evidence of myocardial infarction. It most commonly occurred acutely or within several days following infarction and was more common with recurrent infarction. Peri-infarction block infrequently disappeared and was associated with higher values for serum glutamic-oxalacetic transaminase and a greater mortality in the first year following myocardial infarction. There was no autopsy correlation of peri-infarction block and ventricular aneurysmal formation.

The term "peri-infarction block" is appropriate only when abnormal intraventricular conduction occurs in association with definite electrocardiographic evidence of myocardial infarction.