Semi-automated quantification of vitreal hyperreflective foci in SD-OCT and their relevance in patients with peripheral retinal breaks.

BACKGROUND: Retinal breaks (RB) are emergencies that require treatment to prevent progression of rhegmatogenous retinal detachment. Vitreal hyperreflective foci (VHF) representing migration of RPE cell clusters or interphotoreceptor matrix from the RB are potential biomarkers. The aim of this study is to investigate VHF in RB-patients using SD-OCT. METHODS: The retrospective cross-sectional study included RB patients from our Department of Ophthalmology, HSK Wiesbaden who underwent macular SD-OCT (SPECTRALIS®, Heidelberg Engineering, Germany) on both eyes. VHF, defined and quantified as foci that differ markedly in size and reflectivity from the background speckle pattern, were assessed for presence and frequency. The RB-affected eyes were the study group (G1), the partner eyes the control group (G2). RESULTS: 160 consecutive patients with RB were included. Age was 60 ± 10.2 years (52% female). 89.4% of G1 and 87.5% of G2 were phakic (p = 0.73). 94.4% (n = 151) were symptomatic. Symptom duration was 8.0 ± 10.1 days in G1, 94.4% (n = 151) showed VHF versus 5.6% (p < 0.0001) in G2, of which 75% (n = 6) showed asymptomatic lattice degenerations. Detectable VHF showed a strong association of OR = 320 (95% CI, 110-788, p < 0.0001)) with respect to symptomatic RB. Sensitivity and specificity were 94.7% and 94.7%, respectively. CONCLUSIONS: Most eyes with symptomatic RB show vitreal VHF in SD-OCT. Detected VHF are strongly associated with RB, and our semi-automated greyscale reflectivity analysis indicates that VHF likely originate from photoreceptor complexes torn out of the RB area that migrate into the vitreous cavity. The presence of VHF may indicate RB and should lead to a thorough fundus examination in both symptomatic and asymptomatic cases.

Gender equity imbalance in electrocardiology: A call to action.

Despite the increasing number of women entering the medical profession, senior positions and academic productivity in many fields of medicine remain to be men dominated. We explored gender equity in electrocardiology as perceived by recent academic productivity and also active participation (presidencies and board constituents) in both the International Society of Electrocardiology (ISE) and the International Society for Holter and Noninvasive Electrocardiology (ISHNE). Academic productivity was measured by authorship (first and senior) in the Journal of Electrocardiology (JECG) and the Annals of Noninvasive Electrocardiology (ANE) in 2015. The percentage of women ISE and ISHNE Presidents was 5.6% and 0%, respectively. Current women board constituents for each society was 12.1% for ISE, and 9.4% for ISHNE. JECG articles published in 2015 had considerably less women compared to men for both senior (16.3%) and first (25.3%) authorship. ANE articles published in 2015 followed the same trends in gender, having less women compared to men for both senior (9.4%) and first (19.3%) authorship. There is a gender equity imbalance in the field of Electrocardiology. Identifying a gender imbalance is important for understanding reasons behind these trends, and may also help improve gender equity in Electrocardiology.

Cardiac resynchronization therapy: an updateimpaired left ventricular systolic function.

Cardiac resynchronization therapy has been shown to reduce hospitalization and mortality, and to improve heart failure symptoms, in patients with systolic dysfunction and ventricular dyssynchrony. We review the current guidelines for cardiac resynchronization therapy, the underlying evidence, the latest developments in the field and directions of future research.

Cardioprotection with beta-blockers: myths, facts and Pascal's wager.

Beta-blockers were documented to reduce reinfarction rate more than 3 decades ago and subsequently touted as being cardioprotective for a broad spectrum of cardiovascular indications such as hypertension, diabetes, angina, atrial fibrillation as well as perioperatively in patients undergoing surgery. However, despite lowering blood pressure, beta-blockers have never shown to reduce morbidity and mortality in uncomplicated hypertension. Also, beta-blockers do not prevent heart failure in hypertension any better than any other antihypertensive drug class. Beta-blockers have been shown to increase the risk on new onset diabetes. When compared with nondiuretic antihypertensive drugs, beta-blockers increase all-cause mortality by 8% and stroke by 30% in patients with new onset diabetes. Beta-blockers are useful for rate control in patients with chronic atrial fibrillation but do not help restore sinus rhythm or have antifibrillatory effects in the atria. Beta-blockers provide symptomatic relief in patients with chronic stable angina but do not reduce the risk of myocardial infarction. Adverse effects of beta-blockers are common including fatigue, dizziness, depression and sexual dysfunction. However, beta-blockers remain a cornerstone in the management of patients having suffered a myocardial infarction and for patients with heart failure. Thus, recent evidence argues against universal cardioprotective properties of beta-blockers but attest to their usefulness for specific cardiovascular indications.

[Clinical applications of OCT angiography]. / Klinische Anwendungen der OCT-Angiographie.

BACKGROUND: Optical coherence tomography angiography (OCT-A) allows noninvasive, depth-selective visualization of retinal and choroidal vascular networks by detecting the endoluminal blood flow. This results in three-dimensional high-resolution images which are not possible by regular fluorescein angiography in this spatial resolution. Thus, OCT-A can be used to visualize the microperfusion of retinal and choroidal vessels and their alterations due to diverse pathologies and during the course of therapy. Based on several clinical case reports this article gives an overview of the wide range of applications of OCT-A. METHODS: The OCT-A images were obtained with the Spectralis OCT-2 prototype (Heidelberg Engineering, Heidelberg, Germany). This device provides an increased A scan rate of 70 kHz, which allows the generation of high-resolution OCT volume scans. RESULTS: The areas of application are manifold and include neovascular age-related macular degeneration, diabetic retinopathy, retinal vascular occlusion, inflammatory diseases and telangiectasia of various etiologies. The resulting images and their interpretation differ significantly from regular fluorescein angiography. Knowledge of these differences and of the limitations of this novel diagnostic device are of importance for its clinical application. For certain indications, OCT-A may be used as a substitute for invasive fluorescein angiography and provides more detailed information, particularly due to the absence of blockage phenomena, such as pooling or staining. CONCLUSION: The use of OCT-A allows visualization of the microperfusion of the retinal and choroidal vascular networks and their alterations due to diverse diseases in high resolution and with segmentation of different anatomical layers. The exact interpretation of the three-dimensional OCT-A images and their clinical application are currently under clinical evaluation.

The signal-averaged P wave duration: a rapid and noninvasive marker of risk of atrial fibrillation.

OBJECTIVES: This study was undertaken to determine the ability of the signal-averaged electrocardiogram (ECG) to identify evidence of delayed atrial activation in patients with a history of atrial fibrillation. BACKGROUND: Atrial fibrillation is a reentrant rhythm and depends on atrial conduction delay for its development. The signal-averaging technique is useful for accurately measuring total cardiac activation times, including delayed low amplitude signals, and thus can help identify the substrate for reentrant arrhythmias. METHODS: Standard 12-lead and signal-averaged ECGs were recorded from 15 patients with a documented history of prior paroxysmal or chronic atrial fibrillation and 15 age- and disease-matched control subjects without a history of atrial fibrillation. Signal averaging was performed using an orthogonal lead system with the QRS complex as a trigger and the P wave as a template for the signal-averaging process. Total P wave duration was measured before and after filtering with a least squares fit filter. The P wave complexes on the three bipolar leads were combined into a vector combination of orthogonal leads. The total P wave duration of the individual unfiltered and filtered leads and the vector combination of filtered leads were calculated and used for analysis. RESULTS: The P wave duration by standard ECG was not significantly different in patients with a history of atrial fibrillation and control subjects. Signal-averaged P wave durations were measured from orthogonal leads before and after digital filtering. Mean unfiltered P wave duration was significantly longer in patients with a history of atrial fibrillation than in control subjects (132 +/- 22 vs. 114 +/- 14 ms [p < 0.03] in the X lead, 135 +/- 21 vs. 115 +/- 15 ms [p < 0.03] in the Y lead and 133 +/- 23 vs. 114 +/- 14 ms [p < 0.03] in the Z lead). Mean filtered P wave duration was also longer in patients with atrial fibrillation than in control subjects (151 +/- 23 vs. 130 +/- 19 ms [p < 0.01] in the X lead, 157 +/- 22 vs. 136 +/- 17 ms [p < 0.01] in the Y lead and 154 +/- 23 vs. 135 +/- 15 ms [p < 0.01] in the Z lead). After filtering, a vector composite of orthogonal leads was determined. Again, P wave duration in patients with a history of atrial fibrillation exceeded that in the control subjects (162 +/- 15 vs. 140 +/- 12 ms [p < 0.01]). Using the vector composite of filtered orthogonal leads, a P wave duration > or = 155 ms was associated with a sensitivity of 80%, a specificity of 93% and a positive predictive value of 92% for identifying patients with history of atrial fibrillation. CONCLUSIONS: A prolonged signal-averaged P wave duration may be a simple noninvasive marker of the risk for development of atrial fibrillation.

Selective prolongation of QRS late potentials by sodium channel blocking antiarrhythmic drugs: relation to slowing of ventricular tachycardia. Electrophysiologic Study Versus Electrocardiographic Monitoring Trial (ESVEM) Investigators.

Sodium channel blocking antiarrhythmic drugs have preferential effects on diseased, slowly conducting myocardium, and slowing of tachycardia caused by these drugs may result primarily from further prolongation of conduction time in slowly conducting tissue. In patients with sustained ventricular tachycardia, late potentials detected by signal-averaged electrocardiography (ECG) are thought to arise from slowly conducting ventricular myocardium. This study tested the hypothesis that sodium channel blocking drugs selectively prolong the late potential, or terminal low amplitude signal, portion of the signal-averaged QRS complex and that prolongation of the late potential would correlate with slowing of ventricular tachycardia. Fifty-six drug trials in 32 patients with spontaneous and inducible ventricular arrhythmias were studied. Prolongation of the late potential (11 +/- 15 ms) was significantly greater than prolongation of the initial portion of the QRS complex (4 +/- 9 ms) (p = 0.01). Selective prolongation of the late potential by drugs resulted in significantly greater QRS prolongation detectable by signal-averaged ECG than by standard ECG (p less than 0.0001). In 40 trials in which ventricular tachycardia remained inducible during drug therapy, the increase in induced tachycardia cycle length correlated strongly with the increase in late potential duration (p = 0.005) but not with change in the initial portion of the QRS complex. These data suggest that in patients with ventricular tachycardia, sodium channel blocking antiarrhythmic drugs have preferential effects on slowly conducting tissue and that drug effect on slowly conducting tissue contributes to prolongation of ventricular tachycardia cycle length.

Resolution of cardiomyopathy after ablation of atrial flutter.

OBJECTIVES: We sought to serially assess left ventricular (LV) function before and after catheter ablation of atrial flutter (AFI). BACKGROUND: The relation of tachycardia-induced cardiomyopathy to AFI and its response to direct catheter ablation are unknown. METHODS: LV function was assessed in a series of 59 consecutive patients with successful radiofrequency ablation (RFA) of AFI before and after the procedure. Eleven patients had dilated cardiomyopathy (LV ejection fraction [LVEF] <50%) and congestive heart failure (CHF) symptoms and are the subject of this report. LV function was assessed by LVEF on two-dimensional echocardiography and functional status by New York Heart Association (NYHA) CHF classification. RESULTS: Patients were 59 +/- 8 years old, and were all male. Five patients had a preablation diagnosis of idiopathic cardiomyopathy. The preablation LVEF was 30.9 +/- 11.0% and improved to 41.3 +/- 16% (p = 0.005) when measured 7 months after successful ablation. NYHA CHF class improved from 2.6 +/- 0.5 to 1.6 +/- 0.9 (p = 0.002). Six (55%) of 11 patients had normalization of the LVEF, with complete resolution of CHF symptoms. A lower preablation LVEF and functional class predicted nonresolution of dilated cardiomyopathy (p = 0.002 and 0.001, respectively). CONCLUSIONS: Restoration of normal sinus rhythm by RFA in patients with chronic AFI and cardiomyopathy substantially improved LV function. Resolution of dilated cardiomyopathy occurred in the majority of patients. Tachycardia-induced cardiomyopathy may be a more common mechanism of LV dysfunction in patients with AFI than expected, and aggressive treatment of this arrhythmia should be considered.

Effects of sotalol on the signal-averaged electrocardiogram in patients with sustained ventricular tachycardia: relation to suppression of inducibility and changes in tachycardia cycle length.

OBJECTIVES: This study examines the effects of sotalol on the signal-averaged electrocardiogram (ECG) in patients with spontaneous and inducible sustained ventricular tachycardia and correlates these findings with the effect of sotalol on tachycardia inducibility and tachycardia rate. BACKGROUND: Standard electrocardiography generally does not detect any change in the duration of the QRS complex resulting from sotalol therapy. However, the signal-averaged ECG is more sensitive than the standard ECG for detecting changes in QRS duration induced by antiarrhythmic drugs and can also detect changes in late potential duration. METHODS: Signal-averaged electrocardiography was performed before therapy in 30 patients with spontaneous and inducible ventricular tachycardia, and both electrophysiologic study and a signal-averaged ECG were repeated during therapy with d,l-sotalol. RESULTS: During sotalol therapy the signal-averaged QRS duration decreased by 2.6 +/- 6.6 ms in the 11 patients with no inducible tachycardia during therapy, whereas it increased by 3.8 +/- 5.8 ms (p = 0.01) in the 19 patients with inducible tachycardia during therapy. In the latter group there was a significant positive correlation between prolongation of tachycardia cycle length and prolongation of late potential duration by sotalol (r = 0.56, p = 0.01). CONCLUSIONS: Sotalol can alter QRS and late potential duration as measured by the signal-averaged ECG. Prolongation of QRS duration or late potential duration may reflect a slowing of conduction by sotalol that may interfere with this agent's antiarrhythmic efficacy and slow ventricular tachycardia.

QT dispersion as a marker of risk in patients awaiting heart transplantation.

OBJECTIVES: The objectives of this study were to determine whether a signal-averaged electrocardiogram (SAECG) or measurement of interlead variability of QT intervals on an electrocardiogram (ECG) obtained at the time of wait-listing could provide prognostic value with respect to cardiac death during the waiting period. BACKGROUND: Because heart transplantation is a life-saving but limited resource, there remains an urgent need to identify those patients at greatest risk of dying while awaiting heart transplantation as part of the strategy to optimize the allocation of donor organs to those in greatest need. This study was undertaken to prospectively identify clinical, ECG or SAECG variables that might predict mortality during the waiting period. METHODS: Of 108 consecutive patients referred for heart transplant evaluation, 80 were placed on a waiting list, at which time a standard 12-lead ECG and a SAECG were recorded. In this cohort of 80 patients, QT dispersion was characterized from the 12-lead ECG as either the maximal-minimal QT interval (QTDISP) or as the coefficient of variation of all QT intervals (QTCV). RESULTS: During the 25-month follow-up period (mean time on waiting list, 201 days), the mortality rate was 27%/year, divided equally between heart failure and sudden deaths. No clinical variable identified at entry predicted mortality. QTDISP and QTCV were strong mortality predictors, with a 4.1-fold increase in mortality in patients with QTDISP > 140 ms compared with those patients with QTDISP < or = 140 ms (95% CI 1.1 to 14.9), whereas a QTCV > or = 9% also predicted a 4.1-fold increased risk of death (95% CI 1.4 to 11.8). Although 88% of all SAECGs were abnormal, no patient with a normal SAECG died suddenly during the waiting period. CONCLUSIONS: Indexes of QT dispersion provide a means of stratifying a patient's risk of dying while awaiting heart transplantation and may help to establish priority on a heart transplant waiting list.

Time course of moricizine's effect on signal-averaged and 12 lead electrocardiograms: insights into mechanism of action.

The mechanism of action of moricizine, a new antiarrhythmic agent used in the Cardiac Arrhythmia Suppression Trial, is incompletely characterized. In addition, because moricizine is extensively metabolized, plasma moricizine concentration has an unknown relation to myocardial drug effect. Signal-averaged and standard electrocardiograms (ECGs) were used to monitor moricizine's myocardial effects in 16 patients with frequent ventricular premature complexes taking 600 to 900 mg daily. Three signal-averaged ECG variables were measured: total filtered QRS duration (fQRS), root-mean-square voltage in the terminal 40 ms of the QRS complex (V40) and the terminal low amplitude duration less than 40 microV (LAS). At steady state, plasma samples were collected and serial recordings of signal-averaged and standard ECGs were taken at 0, 1, 2, 4, 6 and 8 h after moricizine administration. A 24 h ambulatory ECG was recorded throughout the test period. Moricizine prolonged the fQRS (p less than 0.05) and decreased the V40 (p less than 0.05) of the signal-averaged ECG and prolonged the QRS (p less than 0.05) and corrected JT (JTc) intervals (p less than 0.05) of the standard ECG. The time course of the signal-averaged and standard ECG variables paralleled plasma moricizine concentration; that is, the maximal changes occurred at 1 to 2 h and declined to time 0 values at 8 h. The maximal changes were: fQRS (+8%), V40 (-33%), QRS (+8%) and JTc (+4%). Thus, dynamic changes were observed for intraventricular conduction (fQRS, QRS) and ventricular repolarization (JTc) over the dosing interval.(ABSTRACT TRUNCATED AT 250 WORDS)

Events in the Cardiac Arrhythmia Suppression Trial (CAST): mortality in patients surviving open label titration but not randomized to double-blind therapy.

The patient characteristics and outcomes were studied in the 318 patients who survived open label drug titration in the Cardiac Arrhythmia Suppression Trial (CAST) and who were not randomized to double-blind therapy and in 942 patients, who were randomized to double-blind placebo therapy. The patients randomized to placebo therapy had a lower total mortality or resuscitated cardiac arrest rate (4% vs. 8.5%). However, at baseline, nonrandomized patients were dissimilar from patients randomized to placebo in the following ways: older; lower left ventricular ejection fraction; greater use of digitalis, diuretic drugs and antihypertensive agents; lesser use of beta-adrenoceptor blocking agents and more frequent prior cardiac problems, including runs of ventricular tachycardia and left bundle branch block. A matched comparison that took these inequities into account showed no significant differences in mortality or rate of resuscitation from cardiac arrest between nonrandomized patients and clinically equivalent patients randomized to placebo. Cox regression analysis indicated that two factors significantly increased the hazard ratio for arrhythmic death or resuscitated cardiac arrest in the nonrandomized patients: female gender (4.7, p less than 0.05) and electrocardiographic events (ventricular tachycardia, proarrhythmia, widened QRS complex, heart block, bradycardia) during open label titration (7.0, p less than 0.005). However, some potentially important differences between men and women were not included in the Cox regression model. Of the nonrandomized patients, approximately 70% were not randomized because of lack of suppression of ventricular premature depolarizations or adverse events, or both, and the remaining 30% because of patient or private physician request with no indication of another reason.(ABSTRACT TRUNCATED AT 250 WORDS)

Efficacy of oral diltiazem to control ventricular response in chronic atrial fibrillation at rest and during exercise.

Although digoxin is often the first choice for control of ventricular response in chronic atrial fibrillation, it fails to slow exercise rates. Diltiazem, a calcium channel antagonist that slows atrioventricular conduction, was administered to 16 patients who failed to achieve adequate rate control on low level exercise testing despite digoxin therapy. Therapeutic response to diltiazem was assessed with submaximal and maximal exercise tests and 24 hour ambulatory electrocardiographic monitoring. During the diltiazem treatment phase, ventricular response at rest diminished (96 +/- 17 versus 69 +/- 10 beats/min, p less than 0.001) as did rate during submaximal exercise (155 +/- 28 versus 116 +/- 26, p less than 0.001), maximal exercise (163 +/- 14 versus 133 +/- 26, p less than 0.001) and average ventricular response during 24 hour monitoring (87 +/- 13 versus 69 +/- 10, p less than 0.001). Rate at rest decreased 26 +/- 15% and submaximal exercise rate diminished 24 +/- 12%. Thirteen (81%) of the 16 patients exhibited at least 15% slowing of rate at rest and during submaximal exercise. Eleven patients (69%) reported alleviation of symptoms. There was no change in serum digoxin levels during diltiazem treatment (1.3 +/- 0.5 versus 1.3 +/- 0.6 ng/ml, p = NS). On withdrawal of diltiazem, ventricular response returned to baseline values. Diltiazem is an effective agent for control of ventricular response, both at rest and during exercise, in digoxin-treated patients with chronic atrial fibrillation.

Atrial fibrillation after minimally invasive direct coronary artery bypass surgery.

OBJECTIVES: The study compared the adjusted risk for developing atrial fibrillation (AF) after minimally invasive direct coronary artery bypass surgery (MIDCAB) and coronary artery bypass graft surgery (CABG). BACKGROUND: Atrial fibrillation results in increased morbidity and delays hospital discharge after CABG. Recently, MIDCAB has been explored as an alternative to CABG. Because of differences in surgical approach between the two procedures, the incidence of AF may differ. METHODS: Randomly selected patients undergoing CABG and MIDCAB were examined. Baseline variables and postoperative course were recorded through review of medical record data. RESULTS: The MIDCAB patients were younger than CABG patients (64+/-12 vs. 67+/-10, p<0.04) and had less extensive coronary artery disease (53% of MIDCAB vs. 3% of CABG had single-vessel disease, while 15% of MIDCAB vs. 69% of CABG had triple-vessel disease, p<0.001 for overall group comparisons). No other differences in clinical or treatment data were noted. Postoperative AF occurred less often after MIDCAB (23% vs. 39%, p = 0.02). Other significant factors associated with postoperative AF included age (p = 0.0024), prior AF (p = 0.0007), left main disease (p = 0.01), number of vessels bypassed (p = 0.009), absence of postoperative beta-blocker therapy (p = 0.0001), and a serious postoperative complication (p = 0.0018). Because of differences between CABG and MIDCAB patients, multivariate logistic analysis was performed to determine independent predictors of postoperative AF. The type of surgery (CABG vs. MIDCAB) was no longer a significant predictor of postoperative AF (estimated relative risk for AF in CABG vs. MIDCAB patients: 1.57, 95% confidence interval (0.82-2.52). CONCLUSIONS: Although AF appears to be less common after MIDCAB than after CABG, the lower incidence is due to different clinical characteristics of patients undergoing these procedures.

Use of the signal-averaged electrocardiogram for predicting inducible ventricular tachycardia in patients with unexplained syncope: relation to clinical variables in a multivariate analysis.

OBJECTIVES: The purpose of this study was to determine the predictors of electrically induced ventricular tachycardia in a large sample of patients with unexplained syncope and to examine the value of the signal-averaged electrocardiogram (ECG) in those patient subsets with varying pretest probability of ventricular tachycardia. BACKGROUND: In patients with unexplained syncope, electrophysiologic study can provide important diagnostic information, such as inducibility of ventricular tachycardia. The signal-averaged ECG can predict inducible ventricular tachycardia, but its utility has not been prospectively studied in a large group of patients with unexplained syncope. METHODS: At six hospitals, 189 consecutive patients with unexplained syncope underwent signal-averaged ECG and electrophysiologic studies. RESULTS: Ventricular tachycardia was induced in 28 patients (15%). Univariate predictors of ventricular tachycardia included history of previous myocardial infarction, reduced left ventricular ejection fraction and abnormal signal-averaged ECG results. The signal-averaged ECG was the most sensitive test but had poor specificity. By multivariate analysis, the signal-averaged ECG and history of previous myocardial infarction were independently predictive. The risk of ventricular tachycardia increased 17-fold in patients with a previous myocardial infarction who also had an abnormal signal-averaged ECG. In patients with no history of previous myocardial infarction, no additional testing was useful in identifying those at risk for inducible ventricular tachycardia. CONCLUSIONS: The signal-averaged ECG was the most sensitive noninvasive test available to predict sustained ventricular tachycardia at electrophysiologic study but was false positive in many patients. A history of previous myocardial infarction followed by the signal-averaged ECG was the most efficient screening process for predicting electrically induced ventricular tachycardia.

Neurally mediated syncope in 2 patients with extracardiac disease.

We describe the cases of 2 patients with repetitive episodes of syncope with profound bradycardia and hypotension. In both patients, the symptoms were initially thought to be neurally mediated and idiopathic but were ultimately determined to be triggered by serious underlying pathologic processes: a massive and locally invasive tumor of the hypopharynx in 1 patient and a gangrenous gallbladder in the other. Appropriate treatment resulted in a resolution of this syndrome in both patients. These cases emphasize the importance of an appropriate evaluation and broad differential diagnoses for patients with severe bradycardia and hypotension.

Comparison of dilated cardiomyopathy and coronary artery disease in patients with life-threatening ventricular arrhythmias: Differences in presentation and outcome in the AVID registry.

BACKGROUND: The etiology of structural heart disease in patients with life-threatening arrhythmias (ventricular tachycardia [VT]/ventricular fibrillation [VF]) may define clinical characteristics at presentation, may require that different therapies be administered, and may cause different mortality outcomes. METHODS: In the Antiarrhythmics Versus Implantable Defibrillators (AVID) registry, baseline clinical characteristics, treatments instituted, and ultimate mortality outcomes from the National Death Index were obtained on 3117 patients seen at participating institutions with VT/VF, irrespective of participation in the randomized trial. By use of these data, 2268 patients with coronary artery disease (CAD) were compared with 334 patients with dilated nonischemic cardiomyopathy (DCM). RESULTS: The CAD group was 7 years older and had a higher percentage of males. DCM patients were more likely to be African American, have severely compromised left ventricular function (52% vs 39%), and have a history of congestive heart failure symptoms (62% vs 44%). Patients with CAD were more likely to be treated with b-blockers and calcium channel blockers and less likely to be treated with angiotensin-converting enzyme inhibitors. Patients with DCM were more likely to be treated with diuretics, warfarin, and an implantable cardioverter defibrillator for VT/VF (54% vs 48% for CAD); the use of other antiarrhythmic therapies did not differ between the 2 groups. Two-year survival was not significantly different between the groups (76.6% [95% CI 74.6%-78.7%] vs 78.2% [95% CI 73.6%-82.9%]). CONCLUSIONS: In AVID registry patients with VT/VF, demographic and clinical characteristics were different between patients with CAD and those with DCM. Despite these differences, overall survival was similar in these 2 groups.

Importance of the endpoint of noise reduction in analysis of the signal-averaged electrocardiogram.

Reduction of random noise by signal averaging is required to uncover ventricular late potentials (LPs). Noise reduction is dependent upon the ambient noise before the study and the number of signal-averaged QRS complexes. Prior studies have used a fixed number of QRS complexes (e.g., 150 to 200) for performing signal-averaged electrocardiograms (SAECGs). Because of variable background noise levels, it was hypothesized that variable noise levels after processing could interfere with detection of LP. Accordingly, SAECGs were performed for each patient to 2 prespecified noise endpoints (expressed as the standard deviation/square root of number of beats): 1.0 microV, which has been used previously as a minimal residual noise level, and 0.3 microV, a low level that generally can be attained in less than 450 beats. Root mean square-voltage noises in the 40-Hz high pass filtered vector magnitude for these studies were 1.36 +/- 0.57 and 0.58 +/- 0.28 microV, respectively. The relative prevalence of LP was evaluated in 3 groups. Group I was comprised of 26 patients with sustained ventricular tachyarrhythmias, group II included 59 patients after myocardial infarction and group III had 14 normal volunteers. The prevalence of LP was greater in group I (69 vs 46%, p less than 0.001) and group II (34 vs 24%, p less than 0.01) with the 0.3-microV studies. In group III, the prevalence did not change (7 vs 7%, difference not significant). The greater detection of LP was due to improved resolution of the terminal low-amplitude QRS segment. Therefore, using the 0.3 microV level instead of 1.0 microV increased sensitivity of LP without loss of specificity.(ABSTRACT TRUNCATED AT 250 WORDS)

Efficacy of bretylium tosylate for ventricular tachycardia.

In 20 patients with inducible ventricular tachycardia (VT), intravenous bretylium tosylate infused as a 10-mg/kg bolus followed by 2 mg/min caused no change in refractory periods and did not suppress inducibility of VT. The use of bretylium for the treatment of VT should be reexamined.