bluuebunny/crossref_metadata_2025_split huggingface dataset:
Prognostic value of an abnormal signal-averaged electrocardiogram in patients with nonischemic congestive cardiomyopathy.
Authors: Mancini D M , Wong K L , Simson M B 
Published: June 2012

BACKGROUND
An abnormal signal-averaged ECG (SAECG) has predictive value for arrhythmic events in patients with coronary artery disease. The purpose of this study was to investigate whether an abnormal SAECG could provide prognostic information in patients with nonischemic dilated cardiomyopathy.

METHODS AND RESULTS
We prospectively obtained SAECGs in 114 patients with dilated nonischemic cardiomyopathy. Twelve-lead ECGs, left ventricular ejection fractions, hemodynamic measurements, and peak exercise oxygen consumption (VO2) also were measured. An SAECG was defined as abnormal by any one of the three following criteria: filtered QRS duration > 120 msec, root-mean-square voltage in the last 40 msec < 20 microV, or duration < 40 microV > 38 msec at 40 Hz. Sixty-six patients had a normal SAECG, 20 patients had an abnormal SAECG, and 28 patients had bundle branch block (BBB). Mean follow-up was 10 +/- 5 months. Age, ejection fraction, peak VO2, pulmonary capillary wedge pressure, and cardiac index were not statistically different among the three groups. Use of antiarrhythmic drugs was similar among the three groups, although patients with BBB had more implantable defibrillators (p < 0.05). The incidence of previous atrial arrhythmias was similar for the three groups. Patients with abnormal SAECG or BBB had more past episodes of sustained ventricular tachycardia and/or sudden death episodes (n = 9) than patients with normal SAECG (n = 1) (p < 0.01). Prospectively, none of the 66 patients with normal SAECG died suddenly or had sustained ventricular arrhythmias. Two deaths occurred from progressive heart failure, and three patients required urgent transplant. In the 20 patients with an abnormal SAECG, four patients had sustained ventricular tachycardia, five patients died suddenly, two patients died from progressive heart failure, and one patient required urgent transplant. In the patients with BBB, four patients had sustained ventricular tachycardia, and four patients required urgent transplant. One-year event-free survival, i.e., absence of ventricular tachycardia and/or death, was 95% in patients with normal SAECG, 88% in patients with BBB, and only 39% in patients with an abnormal SAECG (p < 0.001). Multivariate analysis demonstrated that SAECG and New York Heart Association classification were independent predictors of survival.

CONCLUSIONS
Patients with an abnormal SAECG had a statistically significant increase in sustained ventricular arrhythmias and/or death than did patients with a normal SAECG or BBB. This study demonstrates that an abnormal SAECG is a marker of past and future arrhythmic events in patients with nonischemic dilated cardiomyopathy. In contrast, patients with a dilated cardiomyopathy with a normal SAECG have an excellent prognosis with adverse outcome only from progressive heart failure.
Spontaneous occurrence of symptomatic paroxysmal atrial fibrillation and paroxysmal supraventricular tachycardia in untreated patients.
Authors: Clair W K , Wilkinson W E , McCarthy E A , Page R L , Pritchett E L 
Published: June 2012

BACKGROUND
Ambulatory outpatients (n = 150) with a history of paroxysmal supraventricular arrhythmia were studied to establish the characteristics of the first recurrence of symptomatic tachycardia (time to first recurrence, heart rate during tachycardia, and observed rhythm that was regular versus irregular) when no antiarrhythmic drug was being taken. Baseline variables were examined to assess their impact on time to first recurrence: index arrhythmia (paroxysmal atrial fibrillation [n = 37] versus paroxysmal supraventricular tachycardia [n = 113]), age (mean +/- SD, 43.3 +/- 16.1 years), female sex (n = 71), or presence of other heart or lung disease (n = 53).

METHODS AND RESULTS
Transtelephonic monitoring of the ECG was used to document the rhythm during recurrences of symptomatic tachycardia. Time to first recurrence of symptomatic tachycardia and heart rate during tachycardia were measured, the observed rhythm was classified as irregular (consistent with paroxysmal atrial fibrillation) or regular (consistent with paroxysmal supraventricular tachycardia), and the hour of recurrence was recorded. Advancing age was significantly associated with a decreasing time to first recurrence (p < 0.001); the estimated increase in the hazard function was 25% with each 10 years of advancing age. After the effect of age was adjusted for, neither the classification of arrhythmia (p > 0.2), presence of other heart or lung disease (p > 0.8), nor sex (p > 0.9) was significantly associated with time to first recurrence. Among patients with paroxysmal supraventricular tachycardia, 6.5% had atrial fibrillation recorded at the next symptomatic arrhythmia; among patients with paroxysmal atrial fibrillation, 11.8% had a regular tachycardia recorded at the next symptomatic arrhythmia. There was a circadian pattern to the hour of occurrence of paroxysmal supraventricular tachycardia but not paroxysmal atrial fibrillation.

CONCLUSIONS
Age is more important than other clinical variables, including the ECG classification of a paroxysmal supraventricular arrhythmia in predicting the occurrence of symptomatic arrhythmias. Arrhythmias documented by ECG during symptoms are often different from the arrhythmia documented at the time of referral, which may confound interpretation of antiarrhythmic drug effects.
Positron emission tomography with 11C CGP-12177 to assess beta-adrenergic receptor concentration in idiopathic dilated cardiomyopathy.
Authors: Merlet P , Delforge J , Syrota A , Angevin E , Mazière B , Crouzel C , Valette H , Loisance D , Castaigne A , Randé J L 
Published: June 2012

BACKGROUND
Positron emission tomography (PET) with 11C-labeled CGP-12177 (CGP) has been shown to have the potential to noninvasively measure beta-adrenergic receptor concentration in dog heart. The present study was undertaken to evaluate the clinical value of this technique.

METHODS AND RESULTS
Eight normal subjects and 10 patients with heart failure related to an idiopathic cardiomyopathy were studied. Estimation of beta-receptor concentration was based on a graphic method applied on myocardial PET time-concentration curves obtained after an intravenous injection of 11C-CGP followed 30 minutes later by a coinjection of labeled and unlabeled CGP. The clinical tolerance of these injections was good. Left ventricular concentration of beta-receptors was decreased in patients compared with controls (3.12 +/- 0.51 versus 6.60 +/- 1.18 pmol/mL, respectively; p < 0.001). This 53% decrease agrees with previous in vitro data. In eight of the 10 patients, the beta-receptor concentration obtained from PET was compared with the beta-receptor density determined on left ventricular endomyocardial biopsy samples by in vitro binding technique using 3H-CGP-12177. Results obtained with both techniques were correlated (r = 0.79, p = 0.019). Moreover, decreased beta-receptor concentration correlated with the beta-contractile responsiveness to intracoronary dobutamine infusion (r = 0.83, p = 0.003), indicating a direct link between changes in the receptor number and its biological function.

CONCLUSIONS
PET appears to be a safe and reliable method of assessing in vivo changes in the number of left ventricular beta-adrenergic receptor sites of patients with idiopathic cardiomyopathy.
Cardiotoxicity of human recombinant interleukin-2 in rats. A morphological study.
Authors: Zhang J , Yu Z X , Hilbert S L , Yamaguchi M , Chadwick D P , Herman E H , Ferrans V J 
Published: June 2012

BACKGROUND
One of the side effects of interleukin 2 (IL-2) cancer immunotherapy in humans is the vascular leak syndrome, which is frequently associated with depression of myocardial function, myocarditis, and myocardial necrosis.

METHODS AND RESULTS
To investigate this cardiotoxicity, IL-2 (three doses of 5 x 10(5) Cetus units/day i.p.) was given to rats for 2, 3, or 5 days. Heart, lung, liver, spleen, and kidney tissues were studied by light and electron microscopy and with immunoperoxidase techniques. Cardiac changes consisted of focal lymphocytic and eosinophilic infiltration, myocyte vacuolization, myofibrillar loss, and necrosis. Ultrastructural alterations included swelling of endothelial cells, with dissociation of intercellular junctions, migration of lymphocytes into the interstitium, and interstitial hemorrhage and edema. Close contact between infiltrating lymphocytes, particularly large granular lymphocytes, and cardiac myocytes was often observed in areas of tissue damage. All lesions were more severe on day 5 than on days 2 and 3. Immunoperoxidase stains demonstrated asialo GM1 ganglioside antibody-positive, granular lymphocytes to be much more frequent in myocardium of IL-2-treated rats than in that of control rats.

CONCLUSIONS
Although we cannot exclude the possibility of a direct toxic effect of IL-2 on myocytes, our observations suggest that the myocardial damage produced by this agent is triggered by IL-2-activated lymphocytes that exert cytolytic effects, first on endothelial cells and then on cardiac myocytes, thus producing lesions that involve both the cardiac microcirculation and the muscle cells.
A randomized, prospective comparison of anterior and posterior approaches to radiofrequency catheter ablation of atrioventricular nodal reentry tachycardia.
Authors: Langberg J J , Leon A , Borganelli M , Kalbfleisch S J , el-Atassi R , Calkins H , Morady F 
Published: June 2012

BACKGROUND
Two different techniques have been developed for radiofrequency catheter ablation of typical atrioventricular nodal reentry (AVNRT). Lesions made anteriorly near the apex of the triangle of Koch usually eliminate fast pathway function, whereas lesions made posteriorly near the ostium of the coronary sinus selectively affect slow pathway function. The current study compares the safety, efficacy, and electrophysiological effects of these two techniques in a prospective, randomized fashion.

METHODS AND RESULTS
Fifty consecutive patients with typical AVNRT were randomly assigned to receive radiofrequency lesions either anteriorly (n = 22) or posteriorly (n = 28). If the initial approach failed to eliminate inducibility of AVNRT after 1 hour or 10 applications of radiofrequency energy, the alternative ablation technique was used. Patients underwent repeat electrophysiological testing 48 hours and 3 months after ablation. The primary success rates of the anterior and posterior techniques were similar (55% versus 68%, p = NS). All of the patients who failed the initial approach were successfully treated by the alternative technique without developing high-grade atrioventricular block. One patient developed right bundle branch block during an anterior lesion, and another patient developed complete atrioventricular block as the result of a posterior lesion.

CONCLUSIONS
The posterior approach to radiofrequency catheter modification of the atrioventricular node is as effective as the anterior approach, and both techniques are associated with a low risk of complications. As long as AVNRT persists, it appears safe to cross over from one technique to the other.
Effect of picotamide on the clinical progression of peripheral vascular disease. A double-blind placebo-controlled study. The ADEP Group.
Authors: Balsano F , Violi F 
Published: June 2012

BACKGROUND
Patients with peripheral vascular disease (PVD) undergo a clinical course that can be complicated by cardiovascular events occurring in several areas of the circulation.

METHODS AND RESULTS
In the present study we investigated the ability of picotamide, a substance that inhibits platelet thromboxane A2 (TxA2) synthase and antagonizes TxA2 receptors, to reduce cardiovascular complications in PVD patients. The study was double blind and placebo controlled. After a 1-month run-in period, 2,304 patients were randomly allocated to either placebo or picotamide (300 mg t.i.d.) and followed for 18 months. Major and minor events were analyzed. Results of an "intention-to-treat analysis" were that patients on picotamide suffered 45 major events (3.9%) and 77 minor events (6.7%), whereas those taking placebo suffered 52 major (4.5%) and 99 minor events (8.6%). There was borderline statistical difference between the two groups with respect to the sum of the major and minor events (risk reduction, 18.9%; p = 0.056, log-rank test). Results of an "on-treatment" analysis were that patients on picotamide suffered 40 major (3.8%) and 66 minor events (6.3%), whereas those taking placebo suffered 45 major (4.2%) and 95 minor events (8.9%). The sum of both major and minor events was 106 (10.1%) in the picotamide group and 140 (13.1%) in the placebo group. This difference was significant (risk reduction, 23%; p = 0.029, log-rank test).

CONCLUSIONS
The results of this study indicate that picotamide reduces cardiovascular complications in PVD patients. The apparently low effect of this drug in reducing major events suggests that further studies be made with picotamide in PVD patients who are at high risk of cardiovascular complications so as to further assess its clinical efficacy.
Shock occurrence and survival in 241 patients with implantable cardioverter-defibrillator therapy.
Authors: Grimm W , Flores B T , Marchlinski F E 
Published: June 2012

BACKGROUND
The purpose of this study was to determine the influence of clinical characteristics on shock occurrence and survival in 241 patients with implantable cardioverter-defibrillator (ICD) therapy.

METHODS AND RESULTS
Two hundred forty-one consecutive patients underwent ICD implantation between November 1982 and November 1991 and were subsequently followed for 26 +/- 22 months (intention-to-treat analysis). Actuarial incidence of "appropriate" shocks was 13%, 42%, and 63%, and the incidence of any spontaneous shocks was 15%, 51%, and 76% at 1, 3, and 5 years of follow-up, respectively. Poor left ventricular function (ejection fraction < or = 30%) was associated with an earlier occurrence of both appropriate and any spontaneous ICD shocks (p = 0.001). Appropriate and any spontaneous shocks occurred significantly later in patients who presented with cardiac arrest and in patients in whom only ventricular fibrillation but no uniform ventricular tachycardia was induced during preoperative programmed stimulation. In addition, amiodarone treatment at implant was associated with later occurrence of any spontaneous shocks. Cumulative survival from all-cause mortality including perioperative mortality was 84%, 62%, and 57%, and survival from arrhythmic death was 97%, 89%, and 83% at 1, 3, and 5 years, respectively. Ejection fraction < or = 30% was the best predictor of both total arrhythmic death (p = 0.019) and total mortality (p = 0.003). Antiarrhythmic therapy with class 1 agents at implant was also associated with a higher total mortality during follow-up (p = 0.023) but not with total arrhythmic death. Age, sex, underlying heart disease, clinical presentation, and preoperative response to programmed stimulation did not predict long-term survival. In addition, survival curves were similar for patients with and without spontaneous shocks.

CONCLUSIONS
The majority of patients receive shocks during long-term follow-up. The occurrence of appropriate or any spontaneous shocks during follow-up is not associated with increased arrhythmic or total mortality consistent with effective prevention of sudden cardiac death with ICD therapy in this high-risk patient population. Although low ejection fraction is the strongest predictor of both shock occurrence and mortality during follow-up, no easy algorithm can be derived from the analyzed clinical characteristics to predict which patients will benefit most from ICD implantation.
A prospective randomized repeat-crossover comparison of antitachycardia pacing with low-energy cardioversion.
Authors: Bardy G H , Poole J E , Kudenchuk P J , Dolack G L , Kelso D , Mitchell R 
Published: June 2012

BACKGROUND
Multiprogrammable antiarrhythmia devices can treat monomorphic ventricular tachycardia (VT) with autodecremental overdrive pacing and/or with low-energy cardioversion. These two methods provide the opportunity to decrease patient discomfort typically experienced with high-energy pulses. Although both therapies are known to be effective, controversy persists over their relative safety and efficacy.

METHODS AND RESULTS
The purpose of this study was to examine the safety and efficacy of autodecremental overdrive pacing and low-energy cardioversion in reproducibly terminating monomorphic VT in 24 patients with multiprogrammable antiarrhythmia devices. The protocol required that identical ECG morphology VT be reproducibly induced four times to assess the outcome of antitachycardia pacing and cardioversion twice for each patient in a randomized fashion. Each episode of VT was induced via the implanted device. Autodecremental overdrive pacing initially began with seven stimuli at 97% of the VT cycle length, decrementing by 10 msec per stimulus to a minimum coupling interval of 200 msec. If ineffective, autodecremental overdrive pacing was allowed to iterate three more times for a total of four pacing interventions. With each iteration, one stimulus was added to the pacing train. Similarly, with low-energy cardioversion, up to four therapeutic attempts were made, beginning with a 0.2-J pulse. If ineffective, pulse energy was increased to 0.4, 1.0, and finally 2.0 J. All interventions were automatic without human interference. VT (cycle length, 306 +/- 42 msec) was repeatedly terminated in 15 of 24 patients (63%) by autodecremental overdrive pacing and in 18 of 24 patients (75%) by low-energy cardioversion (p = 0.53). Eight of the 24 patients (33%) had their VT terminated repeatedly by both therapies. VT accelerated to faster VT or ventricular fibrillation by autodecremental overdrive pacing in four of 24 patients (17%) and by low-energy cardioversion in five of 24 (21%) (p = 0.88). Only one of the 24 patients (4%) accelerated with both therapies. No patient was unaffected by either therapy.

CONCLUSIONS
In the manner programmed, autodecremental overdrive pacing and low-energy cardioversion have similar efficacy and acceleration rates. Response to one therapy does not predict response to the other.
Implantable cardioverter-defibrillator therapy in the absence of significant symptoms. Rhythm diagnosis and management aided by stored electrogram analysis.
Authors: Hook B G , Callans D J , Kleiman R B , Flores B T , Marchlinski F E 
Published: June 2012

BACKGROUND
This report describes the value of stored ventricular electrogram analysis in the diagnosis and management of patients experiencing minimal or no symptoms before implantable cardioverter-defibrillator (ICD) therapy.

METHODS AND RESULTS
The study population included 48 patients who received the Cadence Tiered Therapy Defibrillator System, an investigational third-generation ICD with ventricular electrogram storage capabilities. Criteria for arrhythmia diagnosis were based on analysis of the electrogram rate, RR interval variability, and morphology. Twenty-nine of the 48 patients (60%) experienced at least one episode of antitachycardia pacing or shock (one shock or more in 25 of 29 patients) that was preceded by minimal or no symptoms during a mean follow-up of 15.1 +/- 7.8 months. There were 194 tachycardia episodes registered by the device, including 101 for which ventricular electrograms were stored and available for analysis. Of the 101 stored electrograms, 74 were classified as ventricular tachycardia (VT), 24 as non-VT rhythms (atrial fibrillation, 13; supraventricular tachycardia, six; rate-sensing lead disruption, four; T wave oversensing, one), and only three as indeterminate rhythms. Based on the electrogram analysis, changes in tachycardia detection criteria and/or antiarrhythmic drug regimens were implemented and were associated with a reduction in the number of device responses for non-VT rhythms from 24 during the initial study period to three during 11.0 +/- 7.2 months of additional follow-up.

CONCLUSIONS
ICD responses in the absence of symptoms are relatively common in third-generation devices with antitachycardia pacing capabilities. Despite potential limitations such as the effect of bundle branch block on the electrogram morphology during supraventricular tachycardia, the availability of electrogram storage capabilities allowed a presumptive diagnosis of the events precipitating asymptomatic device responses. Device reprogramming based on analysis of stored electrograms was associated with a dramatic reduction in the incidence of ICD responses for non-VT rhythms.
Noninvasive measurement of rate of left ventricular relaxation by Doppler echocardiography. Validation with simultaneous cardiac catheterization.
Authors: Nishimura R A , Schwartz R S , Tajik A J , Holmes D R 
Published: June 2012

BACKGROUND
The instantaneous pressure gradient between the left ventricle and left atrium during systole can be calculated from the mitral regurgitation Doppler velocity curve. The purpose of our study was to determine the accuracy of measuring the time constant of relaxation (TAU) derived from the Doppler mitral regurgitation signal by comparing it with simultaneous high-fidelity left ventricular pressure measurements in humans.

METHODS AND RESULTS
Twenty-five patients had continuous-wave Doppler mitral regurgitation recordings performed with simultaneous high-fidelity left ventricular pressure measurements. Fifteen of these patients had measurements of six to eight beats at various RR intervals. Doppler velocity curves were converted to left ventricular pressure curves by different methods through application of the modified Bernoulli equation at 3-msec intervals. The correlation between catheter-derived and Doppler-derived TAU was best when a zero asymptote and knowledge of the left ventricular end-diastolic pressure were used. A less optimal but acceptable method used the addition of 20 mm Hg to the Doppler-derived ventriculoatrial gradient. Use of a nonzero asymptote for calculation of TAU yielded poor correlation between catheter and Doppler measurements. The correlation of percentage change in Doppler-derived TAU plotted against percentage change in catheter-derived TAU was poor.

CONCLUSIONS
The descending limb of the Doppler-derived mitral regurgitation velocity signal can be used as a semiquantitative estimate of the rate of ventricular relaxation. This method requires knowledge of left atrial pressure and may not be sufficiently accurate for detecting small changes in the rate of relaxation on a beat-to-beat basis.