Risk stratification after myocardial infarction using signal-averaged electrocardiographic criteria adjusted for sex, age, and myocardial infarction location

Incidence and predictors of sudden cardiac arrest in the immediate post-percutaneous coronary intervention period for ST-elevation myocardial infarction: a single-center study

BACKGROUND

Data on the incidence, predictors, and outcomes of sudden cardiac arrest (SCA) in the immediate post-percutaneous coronary intervention (PCI) period for ST-elevation myocardial infarction (STEMI) are limited.

OBJECTIVES

The study aimed to investigate the trends and predictors of SCA occurring within 48 h post PCI for STEMI.

METHODS

We systematically reviewed data from the electronic medical records of 403 patients who underwent PCI for STEMI between January 2014 and December 2019. Trends in the incidence of SCA 48 h post PCI for STEMI were assessed using the Cochrane-Armitage test. Multivariable logistic regression was used to determine the predictors of SCA within 48 h post PCI for STEMI.

RESULTS

Of the 403 patients who underwent PCI for STEMI, 44 (11%) had SCA within 48 h post PCI. The incidence of SCA within 48 h post PCI decreased from 22% in 2014 to 8% in 2019; P = 0.03. After adjusting for underlying confounding variables in the multivariable logistic regression models, out of hospital cardiac arrest [adjusted odds ratio (aOR), 23.9; confidence interval (CI), 10.2-56.1], left main coronary artery disease (aOR, 3.1; CI, 1.1-9.4), left main PCI (aOR, 6.6; CI: 1.4-31.7), new-onset heart failure (aOR, 2.0; CI, 4.3-9.4), and cardiogenic shock (aOR, 5.8; CI, 1.7-20.2) were statistically significant predictors of SCA within 48 h post PCI for STEMI.

CONCLUSION

We identified essential factors associated with SCA within 48 h post PCI for STEMI. Future studies are needed to devise effective strategies to decrease the risk of SCA in the early post-PCI period.

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.

Detection of cardiac involvement in pulmonary sarcoidosis using high-resolution Holter electrocardiogram

BACKGROUND

Early detection of cardiac involvement in patients with sarcoidosis is important but currently unresolved. The aim of this study was to elucidate the utility of frequency domain microvolt T-wave alternans (TWA), signal-averaged ECG (SAECG), and heart rate turbulence (HRT) using 24-hour Holter ECG for detecting cardiac involvement in patients with pulmonary sarcoidosis.

METHODS

This study consisted of consecutive 40 pulmonary sarcoidosis patients (11 males, 62 ± 13 years) who underwent 24-hour Holter monitoring with and without cardiac involvement. All patients underwent frequency domain TWA, SAECG, and HRT using 24-hour Holter monitoring. Patients with atrial fibrillation pacing or wide QRS electrocardiogram were excluded.

RESULTS

After 14 patients were excluded, a total of 26 patients (six males, 59 ± 14 years) were evaluated. Seven patients had cardiac involvement (cardiac sarcoidosis [CS] group). On the Holter SAECG, duration of low-amplitude signals <40 μV in the terminal filtered QRS complex (LAS40) was significantly higher, and root mean square voltage of the terminal 40 ms of the filtered QRS complex (RMS40) was significantly lower in the CS group compared with the non-CS group (LAS40: 61.4 ± 35.9 vs 37.6 ± 9.2 ms; P = .018, RMS40: 11.4 ± 10.3 vs 23.6 ± 13.2 ms; P = .023). Prevalence of positive late potential (LP) was also significantly higher in the CS group than that in the non-CS group (85.7% vs 31.5%; P = .026). The sensitivity, specificity, positive, and negative predictive values of LP for identifying patients with cardiac involvement were 85.7%, 68.4%, 50.0%, and 92.8%, respectively.

CONCLUSION

Holter SAECG may be useful for detecting cardiac involvement in patients with pulmonary sarcoidosis.

Detection of arrhythmogenic substrate within QRS complex in patients with cardiac sarcoidosis using wavelet-transformed ECG

Signal-averaged electrocardiography (SAECG) has been known to be useful for prediction of lethal ventricular arrhythmias (VA). However, this technique has limitations in patients with intraventricular conduction disturbance (IVCD), which is common in cardiac sarcoidosis (CS). Meanwhile, wavelet-transformed ECG (WTECG) has been reported to be useful for detecting arrhythmogenic substrate hidden within QRS complex. The objective of this study was to assess the utility of WTECG for detecting arrhythmogenic substrate in patients with CS. Forty-four CS patients including 18 patients with VA were retrospectively investigated. The parameters on the signal-averaged electrocardiography (SAECG) and the power of frequency components on WTECG were compared between VA group and non-VA group. Eighteen patients have VA (VT: n = 17, VF: n = 1). LP were detected in 17 in VA group and 24 in non-VA group. WTECG showed that high-frequency components (HFC; 80-150 Hz) were developed in VA group. Peak power value at 150 Hz (P150) was significantly higher in VA group than that in non-VA group (442.9 ± 160.2 vs 316.7 ± 100.8, p = 0.006). The receiver operating characteristic (ROC) curve analysis showed an optimal cutoff point of 336 of P150 for detecting patients with VA, with 82.4% sensitivity, 61.5% specificity, and area under the curve of 0.74 (95% confidence interval [CI] 0.59-0.89). WTECG may be useful for detecting CS patients who are prone to VA.

Relationship between P wave peak time and coronary artery disease severity in non-ST elevation acute coronary syndrome

BACKGROUND

Early diagnosis of non-ST elevation acute coronary syndrome (NSTE-ACS) and prediction of the severity of current coronary artery disease (CAD) play a major role in patient prognosis. Electrocardiography has a unique value in the diagnosis and provides prognostic information on patients with NSTE-ACS. In the present study, we aimed to examine the relationship between P wave peak time (PWPT) and the severity of CAD in patients with NSTE-ACS.

METHODS

A total of 132 consecutive patients (female: 35.6%; mean age: 60.1 ± 11.6 years) who were diagnosed with NSTE-ACS were evaluated retrospectively. Gensini scores (GSs) were used to define the angiographic characteristics of the coronary atherosclerotic lesions. The patients were divided into two groups according to the GS. The PWPT was defined as the duration between the beginning and the peak of the P wave, and R wave peak time (RWPT) was defined as the duration between the beginning of the QRS complex and the peak of the R wave.

RESULTS

There were 59 (44.6%) patients in the high-GS group (GS ≥25 ) and 73 (55.3%) patients in the low-GS group (GS <25 ). Presence of diabetes mellitus, low left ventricular ejection fraction, and high RWPT and PWPT were identified as predictors of a high GS in the study population. There was no significant difference between the area under the curves of PWPT and RWPT for predicting the severity of CAD (0.663 vs. 0.623, respectively; p = 0.573).

CONCLUSION

The present study found that both PWPT and RWPT on admission electrocardiography were associated with the severity and complexity of CAD in patients with NSTE-ACS.

The relationship between R wave peak time and left ventricular mass index in patients with end-stage renal disease on hemodialysis

PURPOSE

Cardiovascular complications have been reported to be the main cause of mortality in patients with end-stage renal disease (ESRD). Although left ventricular hypertrophy is the most common clinical presentation of cardiac remodeling, cardiovascular complications may also include disturbances of the heart conduction system. The R wave peak time (RWPT) has been previously associated with left ventricular hypertrophy and myocardial ischemia. In this study, we aimed to investigate the relationship between RWPT and echocardiographic parameters in patients with ESRD.

METHODS

This study enrolled 66 patients (29 females, age 57.2 ± 12.8 years) with ESRD, and 72 controls (37 females, age 55.3 ± 10.1 years) with similar risk factors. All patients underwent electrocardiography and transthoracic echocardiography. The RWPT was defined as the interval between the onset of the QRS complex and the peak of the R or R' wave.

RESULTS

There was no significant difference in terms of clinical and demographic parameters between ESRD patients and controls. Left ventricular ejection fraction was similar between the groups. However, left atrial diameter, interventricular septal thickness, posterior wall thickness, left ventricular mass (LVM) and left ventricular mass index (LVMI) were significantly higher in patients with ESRD. Among electrocardiographic parameters, P wave and QRS complex durations and RWPT were significantly higher in patients with ESRD. Prolonged RWPT, increased LVM and LVMI were identified as associates of ESRD. Furthermore, RWPT correlated well with LVM and LVMI.

CONCLUSION

The present study demonstrated that RWPT prolonged significantly in patients with ESRD. Furthermore, prolonged RWPT has been associated with increased LVM and LVMI.

Prognostic significance of ventricular late potentials in patients with pulmonary sarcoidosis

BACKGROUND

Early detection of cardiac involvement in sarcoidosis is difficult but essential to achieve optimal treatment. Signal-averaged electrocardiography (SAECG) can detect subtle cardiac electrical abnormalities termed late potentials (LPs) and would be useful for the early diagnosis of cardiac involvement.

OBJECTIVE

This study aims to investigate the prognostic significance of LP in patients with pulmonary sarcoidosis.

METHODS

We prospectively studied 74 patients with pulmonary sarcoidosis without overt electrocardiographic abnormalities. All participants underwent SAECG, cardiac echocardiography, and 24-hour ambulatory Holter monitoring. Serum angiotensin-converting enzyme and B-type natriuretic peptide levels were also evaluated. We followed these patients for the evaluation of incidence of cardiac events including cardiac death, arrhythmias, and heart failure requiring hospital admission.

RESULTS

Of the studied population, 29 patients (39.2%) had detectable LP. During a mean follow-up period of 9.8 years, 8 patients with LPs had cardiovascular events, including development of complete atrioventricular block (n = 4), ventricular tachycardia (n = 2), and heart failure (n = 2). Meanwhile, only 1 of 45 patients without LP developed cardiac event (heart failure). Multivariate analyses revealed that LPs were associated with an increased risk of developing cardiac events (hazard ratio 9.66; 95% confidence interval 1.20-78.01; P = .033) whereas age, sex, serum angiotensin-converting enzyme and B-type natriuretic peptide levels, number of premature ventricular contractions on 24-hour Holter monitoring, and echocardiographic parameters were not associated with subsequent cardiac events.

CONCLUSION

SAECG might possibly be useful for the early detection of cardiac sarcoidosis and, if independently validated, could eventually be considered as a screening test for further risk stratification.

The presence of late potentials after percutaneous coronary intervention for the treatment of acute coronary syndrome as a predictor for future significant cardiac events resulting in re-hospitalization

INTRODUCTION

We previously reported that LP positive patients after percutaneous coronary intervention (PCI) had higher rate of re-hospitalization in the small-scale study (135 patients). In this study, we evaluated correlation between LP and later cardiac events leading to re-hospitalization more extensively in greater population.

METHODS AND RESULTS

A 24-h high-resolution (HR) ambulatory electrocardiogram (ECG) was performed in 421 patients that received PCI for the treatment of acute coronary syndrome (ACS) within 30 days. Various baseline characteristics and post-PCI ECG parameters including LP were examined for correlation with later re-hospitalization. LP was evaluated based on 3 different conditions, i.e., the worst, mean and best values, from 24-h signal-averaged QRS wave data. During the post-PCI follow-up period (611 ± 489.0 days), 90 patients were re-hospitalized due to cardiac events. Multivariate analysis identified only positive LP based on the worst value as an independent predictor for re-hospitalization with OR 2.26. Most of re-hospitalization cases (>75%) were predominantly attributed to ischemic events. LP positive population had significantly higher incidences of ischemic events as well as overall re-hospitalization compared to LP negative population. The predictive power of LP was decreased when it was combined with other variables. The receiver operating characteristic analysis determined the LP cut-off values consistent with the LP positive criteria previously reported and standardized.

CONCLUSION

The presence of LP in the 24-h HR ambulatory ECG post-PCI was an independent predictor for a risk of re-hospitalization due to ischemic cardiac events in ACS patients.

Effect of Empagliflozin Versus Placebo on Cardiac Sympathetic Activity in Acute Myocardial Infarction Patients with Type 2 Diabetes Mellitus: Rationale

INTRODUCTION

Protection from lethal ventricular arrhythmias leading to sudden cardiac death is one of the most important problems after myocardial infarction. Cardiac sympathetic hyperactivity is related to poor prognosis and fatal arrhythmias and can be non-invasively assessed with heart rate variability, heart rate turbulence, T-wave alternans, late potentials, and ¹²³I-meta-iodobenzylguanide (¹²³I-MIBG) scintigraphy. Sodium glucose cotransporter 2 (SGLT2) inhibitors potentially reduce sympathetic nervous system activity that is augmented in part due to the stimulatory effect of hyperglycemia. The EMBODY trial is designed to determine whether the suppression of cardiac sympathetic activity induced by the SGLT2 inhibitor is accompanied by protection against adverse cardiovascular outcomes.

METHODS

The EMBODY trial is a prospective, multicenter, randomized, double-blind, placebo-controlled trial in patients with acute MI and type 2 diabetes in Japan. A total of 98 patients will be randomized (1:1) to receive once-daily placebo or empagliflozin, an SGLT2 inhibitor, 10 mg. The primary end point is the change from baseline to 24 weeks in heart rate variability. Secondary end points include the change from baseline for other sudden cardiac death surrogate-markers such as heart rate turbulence, T-wave alternans, late potentials, and ¹²³I-MIBG scintigraphy imaging. Adverse effects will be evaluated throughout the trial period.

PLANNED OUTCOMES

The EMBODY trial will evaluate the potential cardioprotective effect of empagliflozin and will provide additional important new data regarding its preventative effects on sudden cardiac death.

TRIAL REGISTRATION

Unique Trial Number, UMIN000030158 ( https://upload.umin.ac.jp/cgi-open-bin/ctr/ctr_view.cgi?recptno=R000034442 ).

FUNDING

Nippon Boehringer Ingelheim and Eli Lilly and Company.

Association of QRS duration with left ventricular volume and ejection fraction after anterior myocardial infarction assessed by gated single photon emission computed tomography

BACKGROUND

Even intermediate QRS prolongation without bundle branch block is associated with worse clinical outcome after myocardial infarction (MI). We assessed the association of QRS duration with left ventricular (LV) volume and ejection fraction after anterior MI by using quantitative gated single photon emission computed tomography (SPECT).

METHODS

Eighty-two patients with prior anterior MI were enrolled. Intermediate QRS prolongation was defined as QRS duration ≥100 ms without bundle branch block. Quantitative analysis of thallium SPECT was performed on the redistribution image. LV end-diastolic volume (LVEDV), end-systolic volume (LVESV) and ejection fraction (LVEF) were obtained.

RESULTS

There were 25 patients with intermediate QRS prolongation and 57 patients with normal QRS duation. Compared to patients with normal QRS duration, patients with intermediate QRS prolongation had larger LVEDV (137.4 ± 75.1 ml vs 87.9 ± 43.6 ml, p = .004), larger LVESV (89.9 ± 69.6 ml vs 49.2 ± 35.5 ml, p = .009) and lower LVEF (39.3 ± 14.6% vs 47.6 ± 12.0%, p = .02). QRS duration was positively associated with LVEDV (r = 0.49, p < .001) and LVESV (r = 0.47, p < .001), and was inversely associated with LVEF (r= -0.32, p < .001). Multivariate analysis showed that male sex (β = 0.22, p = .04), QRS duration (β = 0.34, p = .002) and number of abnormal Q waves (β = 0.37, p < .001) were associated with LVEDV. QRS duration (β= -0.32, p = .003) and number of abnormal Q waves (β = -0.40, p < .001) were associated with LVEF.

CONCLUSIONS

Our results suggest that QRS duration as well as number of abnormal Q waves is independently associated with LV volume and ejection fraction after anterior MI.

Atrial electrical abnormality in patients with Brugada syndrome assessed by signal-averaged electrocardiography

BACKGROUND

Ventricular fibrillation and atrial fibrillation are well-known arrhythmias in patients with Brugada syndrome. This study evaluated the characteristics of the atrial arrhythmogenic substrate using the signal-averaged electrogram (SAECG) in patients with Brugada syndrome.

METHODS

SAECGs were performed during normal sinus rhythm in 23 normal volunteers (control group), 21 patients with paroxysmal atrial fibrillation (PAF; PAF group), and 21 with Brugada syndrome (Brugada group).

RESULTS

The filtered P wave duration (fPd) in the control, Brugada, and PAF groups was 113.9±12.9ms, 125.3±15.0ms, and 137.1±16.3ms, respectively. The fPd in the PAF group was significantly longer compared to that in the control and Brugada groups (p<0.05). The fPd in the Brugada group was significantly longer than that in the control group (p<0.05) and significantly shorter than that in the PAF group (p<0.05).

CONCLUSION

Patients with Brugada syndrome had abnormal P waves on the SAECG. The abnormal P waves on the SAECG in Brugada syndrome patients may have intermediate characteristics between control and PAF patients.

The association between prolongation in QRS duration and presence of coronary collateral circulation in patients with acute myocardial infarction

BACKGROUND

It is known that QRS duration is related to prognosis in acute myocardial infarction. The relation between QRS duration and coronary collateral circulation is uncertain. In the present study, we aimed to determine the relation between QRS duration and coronary collateral circulation in patients admitted with acute myocardial infarction.

METHODS

The present study was composed of 109 consecutive patients with acute myocardial infarction. All patients had total occlusion in the left anterior descending coronary artery. Electrocardiographic recordings on admission were obtained for the assessment of QRS duration. The Rentrop classification was used to define coronary collateral circulation on coronary angiography. Patients were divided into two groups as follows: Group 1 with poor coronary collateral circulation (Rentrop 0-1) and Group 2 with good coronary collateral circulation (Rentrop 2-3).

RESULTS

Of all patients, 62 patients were included in group 1 and 47 patients in group 2, respectively. In the present study, patients in the group 1 had longer QRS duration than patients in the group 2 (p < 0.005). Additionally, we found that Rentrop grading had negative correlation with both QRS duration and white blood cell count (r: -0.28; p < 0.005 and r: -0.35; p < 0.001).

CONCLUSION

Our study showed that there was an inverse relationship between QRS duration on admission and presence of coronary collateral circulation in patients with acute myocardial infarction.

QRS duration: a novel marker of microvascular reperfusion as assessed by myocardial blush grade in ST elevation myocardial infarction patients undergoing a primary percutaneous intervention

Objectives

Prolonged QRS duration is a predictor of poor prognosis in patients with coronary artery disease. The association between the duration of QRS and myocardial reperfusion is not very well understood. Our aim was to assess the relationship between the measurements of QRS duration and myocardial blush grade (MBG) in patients with ST elevation myocardial infarction (STEMI) who were treated with a primary percutaneous intervention.

Patients and methods

A total of 213 patients (mean age: 57.5±11 years) with STEMI were included. ECG recordings were obtained for the evaluation of the QRS duration before and after primary percutaneous coronary intervention. Angiographic assessment in the infarct-related artery was performed using the MBG. Patients were categorized into two groups of those with impaired microvascular reperfusion (MBG: 0–1) and those with normal microvascular reperfusion (MBG: 2–3).

Results

Overall, 105 and 108 patients had an MBG of 0–1 or 2–3, respectively. There is no significant difference between patient’s characteristics. Despite the absence of a difference between two groups in terms of the QRS duration at presentation (P: 0.57), patients with impaired microvascular reperfusion were found to have longer QRS duration at immediately postprocedure (P: 0.003) and postprocedure 60 min time-points (P<0.001). Correlation analyses showed a positive correlation between pain-to-balloon time and QRS duration at postprocedure 60 min time-points (r: 0.137 and P: 0.04).

Conclusion

Our results suggest that longer QRS duration after angioplasty seemed to indicate the presence of impaired microvascular reperfusion in patients with STEMI.

Frequency and Implications of Ischemia Prior to Ventricular Tachyarrhythmia in Patients Treated With a Wearable Cardioverter Defibrillator Following Myocardial Infarction

BACKGROUND

Autopsy studies imply that recurrent myocardial infarction (MI) accounts for the majority of sudden death early after acute MI, rather than primary arrhythmia. However, diagnosis of recurrent MI by autopsy is challenging and excludes electrocardiographic data to adjudicate arrhythmic causes. We examined the frequency of ischemia prior to treated ventricular tachycardia/fibrillation (VT/VF) and outcomes in patients using the wearable cardioverter defibrillator (WCD) following acute MI.

HYPOTHESIS

Primary arrhythmia, rather than ischemia, is a frequent contributor to sudden death following MI.

METHODS

All patients treated for VT/VF over a 6-year period while wearing a WCD following acute MI with advanced left ventricular dysfunction (ejection fraction ≤35%) were included. Patients with ST-segment changes ≥0.1 mV before VT/VF were classified ischemic. Demographics and clinical outcomes were compared between those with ischemia-mediated vs primary arrhythmia.

RESULTS

Among 273 patients fulfilling study criteria, 15.4% had ischemia prior to VT/VF. Clinical and WCD use characteristics did not significantly differ between ischemic and primary VT/VF groups. Termination of VT/VF by WCD treatment approximated 96% in both groups. Survival 24 hours post-treatment was 88% and 84% (P = 0.54) for patients with and without ischemic VT/VF, respectively. Furthermore, 30-day cumulative survival for those with and without ischemic VT/VF was 77% and 70%, respectively (P = 0.57).

CONCLUSIONS

Ischemia is an infrequent cause of VT/VF following MI, contradicting previous study conclusions that recurrent MI is responsible for most post-MI sudden death. Etiology of VT/VF, however, did not influence defibrillation success or survival, which was high for both groups.

Analysis of speed, curvature, planarity and frequency characteristics of heart vector movement to evaluate the electrophysiological substrate associated with ventricular tachycardia

BACKGROUND

We developed a novel method of assessing ventricular conduction using the surface ECG.

METHODS

Orthogonal ECGs of 81 healthy controls (age 39.0±14.2 y; 51.8% males; 94% white), were compared with iDower-transformed 12-lead ECGs (both 1000Hz), recorded in 8 patients with infarct-cardiomyopathy and sustained monomorphic ventricular tachycardia (VT) (age 68.0±7.8y, 37.5% male, mean LVEF 29±12%). Normalized speed at 10 QRS segments was calculated as the distance traveled by the heart vector along the QRS loop in three-dimensional space, divided by 1/10th of the QRS duration. Curvature was calculated as the magnitude of the derivative of the QRS loop tangent vector divided by speed. Planarity was calculated as the mean of the dihedral angles between 2 consecutive planes for all planes generated for the median beat. Orbital frequency (a scalar measure of rotation rate of the QRS vector) was calculated as a product of speed and curvature.

RESULTS

Mixed regression analysis showed that speed was slower [6.6 (95%CI 4.4-8.9) vs. 24.6 (95%CI 11.5-37.7)µV/ms; P<0.0001]; orbital frequency was smaller [1.4 (95%CI 1.2-1.6) vs. 6.8 (95%CI 5.4-8.1)ms(-1); P<0.0001], and planarity was larger by 3.6° (95%CI 1.4°-5.8; P=0.002) in VT cases than in healthy controls. ROC AUC for orbital frequency was 0.940 (95%CI 0.935-0.944) across all frequencies and QRS segments. ROC AUC for planarity at 70-249Hz was 0.995 (95%CI 0.985-1.00). ROC AUC for speed at 70-79Hz was 0.979 (95%CI 0.969-0.989).

CONCLUSION

This novel method reveals characteristic features of an abnormal electrophysiological substrate associated with VT.

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.

Cardiovascular function and prognosis of patients with heart failure coexistent with chronic obstructive pulmonary disease

BACKGROUND

Chronic obstructive pulmonary disease (COPD) often coexists with heart failure (HF), and is considered to be associated with adverse outcomes in HF patients. However, the features of cardiovascular function and the detailed all-cause mortality of HF with COPD remain unclear.

METHODS AND RESULTS

Consecutive 378 patients admitted for HF who underwent spirometry were divided into three groups: HF without COPD (non-COPD group, n=272), HF with mild COPD (GOLD I group, n=82), and HF with moderate COPD (GOLD II group, n=24). The GOLD II group, as compared to non-COPD group, had (1) higher troponin T (p=0.009); (2) greater cardio-ankle vascular index (p=0.032); and (3) similar cardiac systolic and diastolic function of the right and left ventricle. In addition, rates of cardiac (p=0.049), non-cardiac (p=0.001), and all-cause mortality (p=0.002) were higher in GOLD II group than in non-COPD and GOLD I groups. Importantly, in the Cox proportional hazard analyses, the GOLD stage II was an independent predictor of cardiac (p=0.038), non-cardiac (p=0.036), and all-cause mortality (p=0.015) in HF patients.

CONCLUSIONS

HF patients with coexistent moderate COPD (GOLD stage II) have greater myocardial damage, greater arterial stiffness, and higher cardiac and non-cardiac mortality.

[Ventricular tachycardia in postinfarction patients and coronary heart disease. Treatment and prognostic significance]

Patients with coronary heart disease are subject to an increased risk for sudden cardiac death (SCD). Within the first 30-90 days after the myocardial infarct the risk is particularly high. In times of implantable cardioverter-defibrillator (ICD) on the one hand and the ability to bridge high-risk periods with e. g. wearable defibrillator vests on the other, adequate risk stratification is essential. Currently, the main parameter for this is the left ventricular ejection fraction (LVEF). However, risk stratification by measurement of the LVEF has severe limitations, especially since the majority of patients suffering from SCD have a normal LVEF. Various other methods like ventricular ectopy, signal-averaged ECG, QRS width, microvolt T-wave alternans and programmed ventricular stimulation have been previously evaluated. None of these methods alone or in combination with a left ventricular function assessment was capable of improving the predictability of arrhythmic events significantly. Considering the multiple mechanisms that can lead to SCD, a single risk stratifier seems unrealistic. However, patients with chronic total occlusion of a coronary artery and residual or provocable ischemia have an increased risk for SCD. Therefore a combination of clinical and angiographic parameters seems reasonable. Advanced echocardiographic parameters e.g. mechanical dispersion could be used on a complementary role.

Risk stratification after myocardial infarction: is left ventricular ejection fraction enough to prevent sudden cardiac death?

Patients who have experienced a myocardial infarction (MI) are at increased risk of sudden cardiac death (SCD). With the advent of implantable cardioverter-defibrillators (ICDs), accurate risk stratification has become very relevant. Numerous investigations have proven that a reduced left ventricular ejection fraction (LVEF) significantly increases the SCD risk. Furthermore, ICD implantation in patients with reduced LVEF confers significant survival benefit. As a result, LVEF is the cornerstone of current decision making for prophylactic ICD implantation after MI. However, LVEF as standalone risk stratifier has major limitations: (i) the majority of SCD cases occur in patients with preserved or moderately reduced LVEF, (ii) only relatively few patients with reduced LVEF will benefit from an ICD (most will never experience a threatening arrhythmic event, others have a high risk for non-sudden death), (iii) a reduced LVEF is a risk factor for both sudden and non-sudden death. Several other non-invasive and invasive risk stratifiers, such as ventricular ectopy, QRS duration, signal-averaged electrocardiogram, microvolt T-wave alternans, markers of autonomic tone as well as programmed ventricular stimulation, have been evaluated. However, none of these techniques has unequivocally demonstrated the efficacy when applied alone or in combination with LVEF. Apart from their limited sensitivity, most of them are risk factors for both sudden and non-sudden death. Considering the multiple mechanisms involved in SCD, it seems unlikely that a single test will prove adequate for all patients. A combination of clinical characteristics with selected stratification tools may significantly improve risk stratification in the future.

A new electrocardiographic marker of myocardial reperfusion in patients with acute ST-segment elevation myocardial infarction treated with primary percutaneous intervention: the value of QRS duration

AIMS

Although ischaemia-induced QRS complex changes have been described previously, their relation with reperfusion status is not clear. We aimed to investigate the relation of QRS duration with reperfusion at tissue level compared to myocardial blush in patients with acute myocardial infarction who underwent successful primary percutaneous coronary angioplasty.

METHODS AND RESULTS

One hundred and forty-eight patients were enrolled. Based on the post-angioplasty myocardial blush grade (MBG), patients were divided into reperfusion (grades 2 and 3) and impaired reperfusion (grades 0 and 1) groups. Although the two groups did not differ in terms of admission QRS duration (81±17 vs. 79±15 msec, p=0.473), the patients in the impaired reperfusion group had a significantly longer QRS duration both at immediate post-angioplasty (78±18 vs. 68±17 msec, p=0.001) and at the 60th minute ECG (77±17 vs. 60±17 msec, p<0.001). Patients in the impaired reperfusion group revealed significantly less narrowing of QRS duration in the post-angioplasty 60th minute ECG (6±5 vs. 20±5 msec, p<0.001) when compared to the patients in the reperfusion group. After adjusting all variables, QRS narrowing in the 60th minute ECG was determined as an independent electrocardiographic predictor of reperfusion (OR:1.39, 95% CI: 1.25-1.54, p<0.001).

CONCLUSIONS

We demonstrated that QRS duration is a strong indicator of myocardial reperfusion status.

Effect of dipping status on QRS morphology in patients with hypertension

BACKGROUND

Prolongation of the QRS complex on the surface electrocardiogram (ECG) has been shown to be predictive of cardiovascular outcomes in selected populations. A 'nondipper' blood pressure (BP) profile is currently regarded as a risk factor in its own right for cardiovascular events and target organ damage. The predictive value of ECG parameters in hypertensives with nondipper profile has not been established.

METHODS

A total of 750 consecutive patients with hypertension who had been evaluated with ambulatory BP monitoring were screened for this study. One hundred and thirty-six patients who had fulfilled the inclusion and exclusion criteria were included in the final analysis. Dipper and nondipper patterns were detected and the maximum QRS duration (QRSd) measured on a 12-lead ECG was recorded.

RESULTS

There were 70 nondipper and 66 dipper hypertensives. There was no significant difference between the two groups regarding the daytime systolic and diastolic mean BPs, number of medications taken, and the proportion of each class of antihypertensive medications. Other variables were similar between the two groups. QRSd was significantly higher in nondippers than dippers (P=0.006). Correlation analysis revealed that the systolic BP fall at night was inversely and significantly related with QRSd (r=-0.482, P<0.001). Regression analysis further showed that the systolic BP fall at night and age were independent correlates of QRSd.

CONCLUSION

QRSd on the standard-surface 12-lead ECG was increased in patients with nondipper pattern and furthermore the systolic BP fall at night was independent correlate of QRSd in patients with hypertension.

High prevalence of exercise-induced arrhythmias in catecholaminergic polymorphic ventricular tachycardia mutation-positive family members diagnosed by cascade genetic screening

AIM

Catecholaminergic polymorphic ventricular tachycardia (CPVT) is an inherited cardiac disease predisposing to life-threatening arrhythmias. We aimed to determine the prevalence of arrhythmias and efficacy of beta-blocker treatment in mutation-positive family members diagnosed by cascade genetic screening.

METHODS AND RESULTS

Relatives of six unrelated CPVT patients were tested for the relevant mutation in the ryanodine receptor-2 gene. Mutation carriers underwent an exercise test at inclusion time and 3 months after the initiation of beta-blocker therapy in the highest tolerable dose. The occurrence of ventricular premature beats, couplets, and non-sustained ventricular arrhythmias (nsVT) were recorded in addition to the heart rate at which they occurred. Thirty family members were mutation carriers and were followed for 22 (13-288) months. Previous undiagnosed CPVT-related symptoms were reported by eight subjects. Exercise test induced ventricular arrhythmias in 23 of the 30 mutation carriers. On beta-blocker treatment, exercise-induced arrhythmias occurred at a lower heart rate (117 +/- 17 vs. 135 +/- 34 beats/min, P = 0.02) but at similar workload (P = 0.78). Beta-blocker treatment suppressed the occurrence of exercise-induced nsVT in three of the four patients, while less severe arrhythmias were unchanged. One patient died during follow-up.

CONCLUSION

Exercise test revealed a high prevalence of arrhythmias in CPVT mutation carriers diagnosed by cascade genetic screening. beta-Blocker therapy appeared to suppress the most severe exercise-induced arrhythmias, while less severe arrhythmias occurred at a lower heart rate.

QRS duration and early hemodynamic instability after coronary revascularization surgery

INTRODUCTION AND OBJECTIVES

The duration of the QRS interval measured by ECG is a marker of ventricular dysfunction and indicates a poor prognosis. Its value in patients undergoing coronary revascularization surgery has not been established.

METHODS

The study involved 203 consecutive patients (age 64+/-9 years, 74% male) scheduled for elective coronary surgery. The maximum QRS duration measured on a preoperative 12-lead ECG was recorded. Hemodynamic instability was defined as the occurrence of cardiac death, heart failure, or a need for intravenous inotropic drugs or intra-aortic balloon counterpulsation during the postoperative period.

RESULTS

The occurrence of hemodynamic instability (n=94, 46%) was associated with a longer preoperative QRS duration (97.5+/-21.14 ms vs 88.5+/-16.9 ms; P=.001). The QRS duration was also longer in patients who developed heart failure (n=23; 104.3+/-22.9 ms vs. 91.1+/-18.5 ms; P=.002), needed inotropic drugs (n=77; 96.5+/-20.5 ms vs. 90.1+/-18.2 ms; P=.007) or developed postoperative atrial fibrillation (n=58; 98.2+/-23.8 ms vs. 90.4+/-17.0 ms; P=.018). Bundle branch block was associated with a greater need for intra-aortic balloon counterpulsation (29% vs 12%; P=.012) or inotropic drugs (58% vs 35%; P=.014) and a higher incidence of hemodynamic instability (69% vs 42%; P=.006). Multivariate analysis identified the following independent predictors of hemodynamic instability: QRS duration (adjusted odds ratio [OR] per 10 ms=1.49; 95% confidence interval [CI], 1.11-2; P=.007), the lack of an arterial graft (OR=3.6; 95% CI, 1.14-11.6; P=.029) and extracorporeal circulation time (OR per min=1.013; 95% CI, 1.003-1.023; P=.013).

CONCLUSIONS

The intraventricular conduction delay, or QRS duration, was associated with a higher risk of postoperative hemodynamic instability following coronary surgery.

The role of n-3 PUFAs in preventing the arrhythmic risk in patients with idiopathic dilated cardiomyopathy

BACKGROUND

N-3 polyunsaturated fatty acids (n-3 PUFAs) intake is associated with a reduction in sudden cardiac death in patients with ischemic heart disease. Their effects in patients with heart failure caused by idiopathic dilated cardiomyopathy (IDC) are unknown.

METHODS

We compared with placebo the effects of n-3 PUFAs administration in 44 patients with IDC and with frequent or repetitive ventricular arrhythmias at Holter monitoring using a randomized, double-blind design. Arrhythmic risk was assessed by microvolt T-wave analysis (MTWA), signal averaged ECG (SAECG), Holter monitoring, power spectral analysis of heart rate (HR) variability, catecholamine and cytokine plasma levels, at baseline and after 6 months.

RESULTS

At MTWA, 7/12 patients (58%) initially positive became negative after n-3 PUFAs while one patient became positive after placebo (p = 0.019). N-3 PUFAs administration was also associated to normalization of SAECG (11/15 patients, p < 0.0015), decrease in non-sustained ventricular tachycardia (NSVT) episodes (p = 0.0002) and NSVT HR (p = 0.0003), improvement in HR variability and decrease in catecholamine and cytokine plasma levels. The ratio of plasma n-6 PUFAs to n-3 PUFAs decreased from 12.01 to 3.48 after n-3 PUFAs.

CONCLUSIONS

N-3 PUFAs administration is associated with favorable effects on parameters related to arrhythmic risk in patients with idiopathic dilated cardiomyopathy. These results are consistent with antiarrhythmic activity independent from their antiischemic effects.

Effects of early losartan therapy on ventricular late potentials in acute myocardial infarction

BACKGROUND

Ventricular late potentials (LPs) obtained by the signal-averaged electrocardiogram (SAECG) have prognostic significance as independent predictors of arrhythmic events after an acute myocardial infarction (AMI). Angiotensin receptor blockers reduce the overall mortality and risk of sudden cardiac death in postinfarction patients. The aim of this study was to investigate the effect of early losartan therapy on ventricular LPs, a noninvasive method for the evaluation of arrhythmogenic substrates in AMI patients.

METHODS

The study included 97 patients with their first AMI. Forty-eight patients (39 men and 9 women, aged 58.8 +/- 13.19 years), received early losartan therapy. The control group consisted of 49 patients (38 men and 11 women, aged 59.55 +/- 11.0 years), did not received early losartan therapy. The SAECG was performed at admission and day 14.

RESULTS

The baseline clinical, angiographic characteristics, and reperfusion methods were similar in both groups. The baseline SAECG findings were also similar in the two groups. There was a significant decrease in the rate of LP, between the first and last SAECG recordings, after reperfusion therapy in the losartan group. All of the parameters of LPs were significantly improved in the losartan group on the last SAECG recordings.

CONCLUSION

The results of this study showed that losartan treatment, early after an AMI, reduced the incidence of LP and may thus favorably affect arrhythmia substrates.

Role of electrophysiologic study (EPS)-guided preventive therapy for the management of ventricular tachyarrhythmias in patients with heart failure

BACKGROUND

Ventricular tachyarrhythmias (VT/VF) are 1 of the most important factors determining the prognosis of patients with heart failure (HF). Although priority is given to implantable cardioverter defibrillator (ICD) therapy for the prevention of sudden cardiac death, electrophysiologic-study (EPS)-guided preventive therapy could be important for reducing the number of cardiac events.

METHODS AND RESULTS

Of 864 patients with a history of HF, an EPS was performed in 168 and 121 had inducible VT/VF. Under the basic therapy of an ICD, additional catheter ablation was attempted for 95 of 124 monomorphic VT foci in 74 patients, and 78 of the VT were successfully ablated. The prognoses were compared among 5 patient groups with different results for the EPS and catheter ablation: (1) success group (n=43), (2) failure group (n=15), (3) not attempted group (n=16), (4) VF group (n=47), and (5) no inducible VT/VF group. During a follow-up period of 31+/-22 months, the incidence of VT/VF was lower in the success and no inducible VT/VF groups than in the other groups (p=0.0018), although a significant difference was not observed for the total deaths.

CONCLUSION

EPS-guided preventive therapy using an ICD and catheter ablation can be useful, at least for the reduction of arrhythmic events in patients with HF.

Prediction of arrhythmic events after myocardial infarction based on signal-averaged electrocardiogram and ejection fraction

BACKGROUND

Trials on implantable cardioverter-defibrillators (ICD) for patients after acute myocardial infarction (AMI) have highlighted the need for risk assessment of arrhythmic events (AE). The aim of this study was to evaluate risk predictors based on a novel approach of interpreting signal-averaged electrocardiogram (SAECG) and ejection fraction (EF).

METHODS

SAECG, interpreted with a new index, and EF were prospectively evaluated to predict AE in 144 patients with AMI.

RESULTS

During the mean follow-up period of 4.1 years, 19 AE occurred. The new SAECG index showed a sensitivity of 84%, a specificity of 62%, a positive predictive value (PPV) of 25%, and a negative predictive value (NPV) of 96%. A combination of a normal new SAECG index and an EF >35% resulted in a sensitivity of 100%, a specificity of 47%, a PPV of 22%, and a NPV of 100%; this corresponded to an AE incidence rate of 0%. When both tests were abnormal, the AE incidence rate was 21.3%.

CONCLUSIONS

This is the first contemporary study reporting predictive values based on a combination of SAECG and EF. If confirmed in an appropriately designed and powered trial, this novel approach might be used to identify both patients at very low risk for AE not requiring further risk assessment and patients at high risk in whom ICD implantation can be considered without further risk assessment.

The electrocardiogram as a prognostic tool for predicting major cardiac events

Among patients with cardiac disease, the identification of those who are at low risk and those who are at high risk for major cardiac events is crucial for a rational clinical management of individual patients. A correct noninvasive risk stratification of cardiac patients, in particular, has relevant clinical implications because it would avoid unnecessary exposure to potentially risky invasive diagnostic or interventional procedures in low-risk patients, whereas it would allow an appropriate aggressive diagnostic and therapeutic approach in high-risk patients. Furthermore, the appropriate identification of low- and high-risk patients would also have social and economic implications by favoring optimization of resource distribution and costs. A large number of studies in previous decades provided evidence that several methods and variables derived from the analysis of the electrocardiogram (ECG) are powerful predictors of major cardiac events in several clinical conditions. Despite that, there has been limited attention about how several of these findings can be used in clinical practice. Furthermore, in recent years, most studies about risk stratification of cardiac patients have mainly been focused on the use of a number of serum/plasma biomarkers with reduced attention to ECG variables. Surprisingly, however, there have been few attempts to establish whether the various proposed risk markers add any significant information to that obtainable from ECG methods. In this article, the evidence for the prognostic value of variables derived from the assessment of the ECG signal by several methods and techniques will be briefly reviewed. Because of the largeness of the topic, this review will be necessarily incomplete. Because most of the clinical research in this field concerned risk stratification of patients with coronary artery disease, the article will be largely focused on this population of patients. The role of ECG methods in specific cardiac diseases and, in particular, in the general population of asymptomatic subjects will be briefly discussed when believed appropriate and helpful. Furthermore, only major clinical events (ie, cardiac death, arrhythmic events, acute myocardial infarction) will be taken into account as end points in this article. Minor clinical events (eg, coronary revascularization procedures, coronary artery restenosis, recurrences of symptoms) are indeed less robust as end points because they are widely biased by subjective judgments.

Relation of admission QRS duration with development of angiographic no-reflow in patients with acute ST-segment elevation myocardial infarction treated with primary percutaneous interventions

BACKGROUND

Although QRS-complex changes during ischemia have been described previously, their relation with no-reflow is not clear.

PURPOSE

To evaluate relation of admission QRS duration with angiographic no-reflow, we studied 162 patients who underwent primary angioplasty.

METHODS

Twelve-lead electrocardiogram with a paper speed of 50 mm/s was recorded on admission and repeated after angioplasty. Patients were divided into reflow and no-reflow groups based on postangioplasty coronary thrombolysis in myocardial infarction flow grade.

RESULTS

Patients in the no-reflow group (26 patients) were older (P = .001) and had significantly longer pain-to-balloon interval (P = .007). The patients in the no-reflow group had significantly longer QRS duration on admission electrocardiogram compared with patients in the reflow group (interquartile range, 80-93 [median, 84] milliseconds vs 60-80 [median, 76] milliseconds, respectively; P < .001). After adjusting all variables, QRS duration on admission was found to be independently related to angiographic no-reflow (odds ratio, 1.07; 95% confidence interval, 1.02-1.12; P = .003).

CONCLUSION

QRS duration on admission may be valuable in predicting no-reflow.

Effects of atorvastatin on ventricular late potentials and repolarization dispersion in patients with hypercholesterolemia

Emerging evidence suggests that statins have a favorable impact on the reduction of arrhythmia events and sudden cardiac death in patients with structural heart disease. We aimed to investigate the possibly and directly favorable effects of statins on ventricular late potentials, QT dispersion, and transmural dispersion of repolarization attained by analyzing clinical electrocardiography (ECG) risk stratification parameters in patients with hypercholesterolemia without structural heart disease. In total, 82 patients (45 females; mean age, 62 +/- 10 years) with hypercholesterolemia were enrolled in this prospective study to examine the effects of statin therapy (atorvastatin 10 mg/day for 3 months) on ECG risk stratification parameters. Surface 12-lead ECG and signal-average ECG (SAECG) were recorded before and after statin treatment. The SAECG parameters, QT dispersion, Bazett-corrected QT (QTc) dispersion, T wave peak-to-end interval (Tpe), and percentage of Tpe/QT interval were calculated and compared before and after statin therapy. Twelve-lead ambulatory 24-hour ECGs were recorded in 12 patients. The results demonstrated that after statin therapy for 3 months, serum levels of total cholesterol and low-density lipoprotein cholesterol were significantly reduced (both p values < 0.001). However, neither significant changes of each SAECG parameter nor the frequency of late potentials were demonstrated after atorvastatin therapy. In addition, no significant changes in QT dispersion, QTc dispersion, Tpe, or Tpe/QT were found. However, 24-hour ambulatory ECG revealed a flattening effect of circadian variation of QTc dispersion after atorvastatin therapy. In conclusion, the favorable antiarrhythmia effect of atorvastatin (10 mg/day) therapy cannot be directly reflected by analyzing these noninvasive ECG risk stratification parameters in low-risk patients with hypercholesterolemia.

Clinical usefulness of electrophysiologic study (EPS)-guided risk stratification for life-threatening arrhythmia in patients with heart failure

BACKGROUND

Ventricular tachyarrhythmia is one of the most important factors determining the prognosis of patients with heart failure and sudden death can be observed even during stable therapy controlling clinical heart failure. In this study, the usefulness of electrophysiologic study (EPS) for the prediction of a future arrhythmic event was evaluated in patients with heart failure.

METHODS AND RESULTS

The patient population consisted of 474 patients with a history of clinical heart failure but without an episode of spontaneous sustained ventricular tachycardia or fibrillation (VT/VF). A Holter ECG was performed in all patients, and 177 of the 474 patients underwent EPS because of a recording of nonsustained VT (NSVT, > 5 beats). When sustained VT/VF was inducible in EPS, the patient was assigned to implantation of a defibrillation device. The patients were divided into 3 groups, ie, 1) no NSVT (n = 297), 2) NSVT + no inducible VT/VF (n = 134), and 3) NSVT + inducible VT/VF (n = 43), and were followed-up for > 12 months. All patients were followed-up under standard therapy for heart failure. There were no significant differences in basic clinical characteristics and therapies among the 3 groups. During the follow-up period of 32 +/- 18 months, 56/474 patients suffered a VT/VF episode, ie, 21/297 in no NSVT, 14/134 in NSVT + no inducible VT/VF, and 21/43 in NSVT + inducible VT/VF patients (P = 0.032). All patients were rescued from sudden death among patients with an implanted defibrillator, but 11 patients without a defibrillator died.

CONCLUSION

In patients with heart failure, future arrhythmic events could be predicted by EPS and Holter ECG. EPS-guided risk stratification seems to be useful in managing patients with heart failure.

Sudden cardiac death: the role of risk stratification

Sudden cardiac death syndrome remains a major health problem responsible for approximately 400,000 deaths annually in the US. Effective therapies exist but are costly and are associated with potential complications. Currently used strategies for selection of the best candidates for implantable cardioverter defibrillator (ICD) therapy are imperfect and leave a large number of high-risk patients unprotected. At the same time, many patients who received ICDs will never develop tachyarrhythmia and require ICD intervention. The article summarizes the current status and applicability of the noninvasive and invasive tests used for sudden cardiac death risk assessment with the emphasis on the increasingly recognized value of microvolt T wave alternans.

Role of Electrophysiologic Studies, Signal‐Averaged Electrocardiography, Heart Rate Variability, T‐Wave Alternans, and Loop Recorders for Risk Stratification of Ventricular Arrhythmias

Ventricular tachycardia and fibrillation are major causes of morbidity and mortality after myocardial infarction. Frequently, sudden cardiac death is the first manifestation of such malignant rhythms. Optimal risk stratification strategies in this population are of utmost importance. In this review the authors discuss the background and clinical use of invasive tests, such as electrophysiologic study and implantable loop recorders, and noninvasive tests, such as signal-averaged electrocardiography, heart rate variability, and T-wave alternans. The utility, indications, and limitations of each test in clinical practice are discussed, especially for the purpose of postmyocardial infarction risk stratification in the elderly population.

Is the change of late potential over time related to enzyme levels? Ischemic burden in acute myocardial infarction

BACKGROUND

The ventricular late potential (VLP) detected using the technique of signal average electrocardiography (SAECG) interacts with several factors, primarily time.

METHOD

In this study, we examined the interaction, over time, of VLP with the initial ischemic burden and enzyme levels in acute myocardial infarction. Patients diagnosed as having acute myocardial infarction were included in the study. On the first day, the patients underwent enzyme analysis and electrocardiography (ECG) follow-up every 6 hours. A 24-hour ambulatory ECG was performed on the seventh day in order to determine the ischemic burden. SAECG findings (TQRS, RMS, LAS) were obtained on the seventh day, in the first and third months. The study was continued with the patients who did not require angioplasty as decided with angiographic evaluation in the first month.

RESULTS

The study included 30 patients with acute myocardial infarction (mean age 51 +/- 12, 28 males and 2 females). The initial mean CK-MB levels and the mean ischemic burden were 98 +/- 31 U/L and 44 +/- 96 minutes. The TQRS (ms), LAS (ms), and RMS (microV) values (mean +/- SD ) obtained at day 7, month 1, and month 3 are 97 +/- 12, 96 +/- 9, 103 +/- 11, P = 0.01; 31 +/- 10, 31 +/- 11, 32 +/- 10, P = 0.46; 43 +/- 28, 41 +/- 26, 33 +/- 25, P = 0.01, respectively. We observed that the TQRS and RMS values changed significantly with time, but these levels of significance disappeared when adjusted for the initial ischemic burden and CK-MB levels (P = 0.06; P = 0.53). The VLP frequency was 33% at day 7 and 23% at month 3. Unlike the CK-MB level, the initial ischemic burden was significantly different between the patients with and without VLP at month 3 (150.85 +/- 149.28, 12.34 +/- 26.48, P = 0.001 ). When tested together with age and gender, it was found that the high initial ischemic burden increased the possibility of VLP (OR: 24, CI: 2.09-279.52, P = 0.01 ) at month 3.

CONCLUSION

SAECG findings in patients with myocardial infarction changed with time; however, this change occurred depending on the initial ischemic burden and CK-MB levels. Of these, only the initial ischemic burden, especially in high levels, was a determinant for the presence of VLP in the late period of myocardial infarction.

QRS Duration in High-Resolution Methods and Standard ECG in Risk Assessment After First and Recurrent Myocardial Infarctions

BACKGROUND

Prolonged QRS duration (QRSd) is associated with increased mortality after myocardial infarction (MI). Only little data exist about its predictive ability and relationships to clinical variables in the present era of active treatment of myocardial ischemia and cardiac dysfunction. We investigated whether QRSd in high-resolution methods and standard ECG predict arrhythmic events and cardiac death in post-infarction patients with cardiac dysfunction and how it relates to clinical variables, with a special emphasis on history of previous MI.

METHODS AND RESULTS

Patients (n = 158) with acute MI and cardiac dysfunction had magnetocardiography (MCG), signal-averaged ECG (SAECG), and ECG registered at discharge. Patients with a previous MI had significantly longer QRSd although their left ventricular function was almost similarly impaired. During the mean follow-up of 50 +/- 15 (range 1-72) months, 32 patients died and 17 (53%) of the deaths were classified as cardiac. Eighteen patients had an arrhythmic event. QRSd >121 ms in MCG and >114 ms in SAECG were significant predictors of arrhythmic events and cardiac death, whereas QRSd in ECG predicted only cardiac death. In multivariate analysis, QRSd in MCG (hazard ratio (HR) = 3.6, P = 0.007) and SAECG (HR = 4.6, P = 0.016) predicted only arrhythmic events, whereas QRSd in ECG was an independent predictor of cardiac death.

CONCLUSIONS

Prolonged QRSd in MCG and SAECG are powerful indicators of the arrhythmia substrate in post-infarction patients with cardiac dysfunction, whereas prolonged QRSd in standard ECG associates with increased risk of cardiac death.

Ventricular late potentials in familial amyloidotic polyneuropathy

We investigated the occurrence of ventricular late potentials (LPs) in patients with familial amyloidotic polyneuropathy (FAP) and the possible association with ventricular arrhythmia on Holter electrocardiography and echocardiographic data. Fifty-five patients and 94 healthy controls were studied. LP were found in 46% of the FAP patients older than 60 years and in 15% of the controls (P = .02), whereas no difference was found in individuals younger than 60 years. The occurrence of LP was associated with nonsustained ventricular arrhythmia in the older FAP patients (P = .04). Older patients with LP had increased ventricular septum thickness (P = .02) and left posterior wall thickness (P = .01), as compared with those without LP. In conclusion, ventricular LPs are common in the FAP patients older than 60 years and associated with nonsustained ventricular arrhythmia and increased thickness of the left ventricular wall. Long-term follow-up studies are required to find the prognostic significance of these new findings.

Sudden death in patients with myocardial infarction and left ventricular dysfunction, heart failure, or both

BACKGROUND

The risk of sudden death from cardiac causes is increased among survivors of acute myocardial infarction with reduced left ventricular systolic function. We assessed the risk and time course of sudden death in high-risk patients after myocardial infarction.

METHODS

We studied 14,609 patients with left ventricular dysfunction, heart failure, or both after myocardial infarction to assess the incidence and timing of sudden unexpected death or cardiac arrest with resuscitation in relation to the left ventricular ejection fraction.

RESULTS

Of 14,609 patients, 1067 (7 percent) had an event a median of 180 days after myocardial infarction: 903 died suddenly, and 164 were resuscitated after cardiac arrest. The risk was highest in the first 30 days after myocardial infarction--1.4 percent per month (95 percent confidence interval, 1.2 to 1.6 percent)--and decreased to 0.14 percent per month (95 percent confidence interval, 0.11 to 0.18 percent) after 2 years. Patients with a left ventricular ejection fraction of 30 percent or less were at highest risk in this early period (rate, 2.3 percent per month; 95 percent confidence interval, 1.8 to 2.8 percent). Nineteen percent of all sudden deaths or episodes of cardiac arrest with resuscitation occurred within the first 30 days after myocardial infarction, and 83 percent of all patients who died suddenly did so in the first 30 days after hospital discharge. Each decrease of 5 percentage points in the left ventricular ejection fraction was associated with a 21 percent adjusted increase in the risk of sudden death or cardiac arrest with resuscitation in the first 30 days.

CONCLUSIONS

The risk of sudden death is highest in the first 30 days after myocardial infarction among patients with left ventricular dysfunction, heart failure, or both. Thus, earlier implementation of strategies for preventing sudden death may be warranted in selected patients.

High-Resolution Analysis of Ambulatory Electrocardiograms to Detect Possible Mechanisms of Premature Ventricular Beats

For generations of electrocardiogram (ECG) analysis, the presence of premature ventricular beats (PVBs) has been characterized as a common event in the ECG without regard to the mechanism which has caused the PVB in the first place. At best, the coupling interval with the preceding sinus beat may be noted. This viewpoint persisted throughout the era of automated ECG analysis, as well as influencing the treatment of more life threatening events by PVB suppression strategies alone. This study proposed three hypotheses which would link the PVB to a specific mechanism or milieu. Each of these hypotheses requires significant signal processing of the continuously recorded high resolution ECG. Data are presented which demonstrate that abnormal intra-QRS potentials may be linked to a reentrant mechanism for the PVBs and that many patients have significant changes in these potentials in the sinus beats preceding the PVB. Changes in the characteristics of the repolarization as measured in the T/U wave period were also observed and could be linked to triggered activity mechanism for some PVBs. Finally, the role of subclinical ST segment changes also indicates that low grade ischemia may play a role in modulating either PVB mechanism. The data generated by this study suggest that a new view toward PVB mechanism as measured by ECG characteristics may warrant a more rational approach to renewed interest identifying the malignant PVBs and their eventual clinical management.

Reduced prognostic power of ventricular late potentials in post-infarction patients of the reperfusion era

AIMS

To test the prognostic value of ventricular late potentials (LPs) in a large cohort of post-infarction patients in the modern reperfusion era.

METHODS AND RESULTS

1800 consecutive survivors of acute myocardial infarction in sinus rhythm and under 76 years of age were enrolled. Many (99%) of the patients received reperfusion/revascularization therapy (91% percutaneous coronary intervention) and up-to-date pharmacological treatment (99% aspirin, 93% beta-blockers, 90% ACE-inhibitors, and 85% statins). LPs were calculated in 968 patients and found to be present in 90 (9.3%). The primary endpoint was the composite of cardiac death and serious arrhythmic events. The secondary endpoint was the composite of sudden cardiac death and serious arrhythmic events. During follow-up (median 34 months), 26 patients reached the primary endpoint. The presence of LPs was not significantly associated with the primary endpoint in univariable or multivariable analysis. In contrast, low (< or = 30%) left ventricular ejection fraction (hazard ratio 9.6, 95% confidence interval 4.1-22.4), heart rate turbulence category 2 (7.5, 2.4-23.9) and category 1 (5.3, 1.9-14.9) were significant predictors in both univariable and multivariable analysis.

CONCLUSION

Ventricular LPs are of limited use for risk stratification in unselected post-infarction patients in the modern reperfusion era.

Clinical Implications of Intermediate QRS Prolongation in the Absence of Bundle-Branch Block in Patients With ST-Segment-Elevation Acute Myocardial Infarction

BACKGROUND

In the reperfusion era the clinical characteristics of intermediate QRS prolongation without bundle-branch block (BBB) remain unclear in patients with ST-segment elevation myocardial infarction (STEMI).

METHODS AND RESULTS

A total of 465 patients with STEMI within 24 h of onset were classified into 3 groups according to QRS duration on presenting electrocardiograms: 338 patients had QRS duration <100 ms (group N), 71 had QRS duration >or=100 ms without BBB (group W), and 56 had BBB (group B). The frequency of Killip class >1 was higher in group W (28%) than in group N (12%), but lower than in group B (47%) (p<0.05, respectively). The percentages of patients with non-anterior infarction (69% vs 42%, 47%), 3-vessel disease (30% vs 9%, 16%), and coronary artery bypass graft surgery (24% vs 4%, 13%) were higher in group W than in groups N and B (all p<0.05). In group W, 6-month-mortality was similar to that in group N, but lower than that in group B (4%, 3% vs 25%, p<0.05 respectively).

CONCLUSIONS

In the reperfusion era, although patients with intermediate QRS prolongation without BBB have more severe coronary disease, 6-month-mortality is similar to those with normal conduction, but lower than those with BBB.