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Biomedical subjects

Paul A Friedman

Publications and source records attributed to Paul A Friedman.

At least 19 recordsLinked to original sources
PubMed2007

Percutaneous endocardial and epicardial ablation of hypotensive ventricular tachycardia with percutaneous left ventricular assist in the electrophysiology laboratory.

Ventricular tachycardia (VT) in the setting of structural heart disease is challenging to treat with percutaneous catheter ablation due to the presence of complex substrate, multiple morphologies, hemodynamic instability, and epicardial circuits. When substrate-based approaches fail, however, it may be impossible to map and ablate hemodynamically unstable arrhythmias. We describe a novel approach to endocardial and epicardial mapping and ablation of hypotensive VT using a percutaneous left ventricular assist device in the electrophysiology laboratory, permitting near-surgical access to cardiac structures.

Assisted Circulation↗
PubMed2006

Frequency of permanent pacemaker or implantable cardioverter-defibrillator infection in patients with gram-negative bacteremia.

BACKGROUND: Despite the frequent occurrence of bacteremia due to gram-negative organisms in patients with underlying permanent pacemakers (PPMs) or implantable cardioverter defibrillators (ICDs), the outcome and treatment of these patients has received scant attention. In patients with PPMs or ICDs who have Staphylococcus aureus bacteremia, 45% have PPM/ICD infection. METHODS: We conducted a retrospective cohort study over a 7-year period to assess the clinical features and frequency of PPM/ICD infection in patients with gram-negative bacteremia, as well as the incidence of relapse in patients for whom the device was not removed. RESULTS: Forty-nine patients were included in the study; 3 (6%) had either definite (2 patients) or possible (1 patient) PPM/ICD infection. Both patients with definite PPM/ICD infection had clear infection of the generator pocket. None of the other patients with alternate sources of bacteremia developed PPM/ICD infection. Thirty-four patients with retained PPM/ICD were observed for >12 weeks (median time, 759 days), and 2 (6%) developed relapsing bacteremia, although they each had alternative sources of relapse. CONCLUSIONS: In sharp contrast to S. aureus infection, PPM/ICD infection in patients with gram-negative bacteremia was rare, and no patients appeared to have secondary PPM/ICD infection due to hematogenous seeding of the system. Despite infrequent system removal in these patients, relapsing bacteremia among patients who survived initial bacteremia was rarely seen. If secondary PPM/ICD infection occurs in patients with gram-negative bacteremia, it is either uncommon or it is cured with antimicrobial therapy despite device retention.

Aged↗
PubMed2006

Dual-chamber versus single-chamber detection enhancements for implantable defibrillator rhythm diagnosis: the detect supraventricular tachycardia study.

BACKGROUND: Delivery of inappropriate shocks caused by misdetection of supraventricular tachycardia (SVT) remains a substantial complication of implanted cardioverter/defibrillator (ICD) therapy. Whether use of optimally programmed dual-chamber ICDs lowers this risk compared with that in single-chamber ICDs is not clear. METHODS AND RESULTS: Subjects with a clinical indication for ICD (n=400) at 27 participating centers received dual-chamber ICDs and were randomly assigned to strictly defined optimal single- or dual-chamber detection in a single-blind manner. Programming minimized ventricular pacing. The primary end point was the proportion of SVT episodes inappropriately detected from the time of programming until crossover or end of study. On a per-episode basis, 42% of the episodes in the single-chamber arm and 69% of the episodes in the dual-chamber arm were due to SVT. Mortality (3.5% in both groups) and early study withdrawal (14% single-chamber, 11% dual-chamber) were similar in both groups. The rate of inappropriate detection of SVT was 39.5% in the single-chamber detection arm compared with 30.9% in the dual-chamber arm. The odds of inappropriate detection were decreased by almost half with the use of the dual-chamber detection enhancements (odds ratio, 0.53; 95% confidence interval, 0.30 to 0.94; P=0.03). CONCLUSIONS: Dual-chamber ICDs, programmed to optimize detection enhancements and to minimize ventricular pacing, significantly decrease inappropriate detection.

Aged↗
PubMed2006

Effects of a rate smoothing algorithm for prevention of ventricular arrhythmias: results of the Ventricular Arrhythmia Suppression Trial (VAST).

BACKGROUND: Rate smoothing, which is available in some pacemakers and implantable cardioverter defibrillators (ICDs), has been used to prevent Torsades de Pointes in patients with long QT syndrome. Its efficacy in general ventricular arrhythmia prevention has not been determined. OBJECTIVES: The purpose of the Ventricular Arrhythmia Suppression Trial (VAST) was to prospectively investigate whether rate smoothing could significantly reduce the incidence of ventricular tachyarrhythmias in a large, broad population of patients with ICDs. METHODS: Five hundred sixty-nine patients were enrolled at 57 participating centers and implanted with a commercially available Guidant ICD. A single-blinded crossover design was used in which each patient was randomized at implant to one of two treatment sequences: either rate smoothing on (RS On) followed by rate smoothing off (RS Off), or RS Off followed by RS On. This mode sequence was randomly determined and assigned in a 1:1 fashion using randomized permuted blocks by site. Each mode was followed for 6 months. Programming of rate smoothing was prescribed as 12% Down and 12% Up for the duration of the RS On period. RESULTS: Of enrolled patients, 281 were randomized to RS Off followed by RS On, and 288 to RS On followed by RS Off. With RS On, 75 (23%) patients experienced a reduction in arrhythmias, 76 (23%) saw an increase in arrhythmias, and the remaining 176 (54%) had no difference. No significant difference (P = .58) in frequency of arrhythmias with RS On vs RS Off was found. CONCLUSION: Rate smoothing does not result in a reduction in ventricular arrhythmias in a heterogeneous population of patients receiving ICDs.

Adult↗
PubMed2006

Relapse and mortality following cardioversion of new-onset vs. recurrent atrial fibrillation and atrial flutter in the elderly.

AIMS: Trials of rate control vs. rhythm control for atrial fibrillation or flutter included few patients with new-onset arrhythmia. Our objective was to assess the relapse rate and the effect of the relapse of new-onset atrial arrhythmias on mortality after direct-current cardioversion (DCCV). METHODS AND RESULTS: A cohort of 351 patients with atrial fibrillation (new onset in 179) and 126 patients with atrial flutter (new onset in 78) was followed-up after DCCV. Cox proportional hazard models were used. Median age was 74.6 years. Mean follow-up for relapse was 7.7 months; for death, 29.4 months. Patients with new-onset atrial flutter [adjusted hazard ratio (HR) = 1] were more likely to maintain sinus rhythm than the patients with recurrent atrial flutter (adjusted HR = 2.5, P < 0.01), new-onset atrial fibrillation (adjusted HR = 2.4, P < 0.01), or recurrent atrial fibrillation (adjusted HR = 2.7, P < 0.01). Patients with new-onset atrial fibrillation were as likely to have relapses as patients with recurrent atrial fibrillation or flutter. Relapse of atrial arrhythmia after DCCV was associated with increased mortality (adjusted HR= 3.1, P < 0.01). CONCLUSION: DCCV is more successful in maintaining sinus rhythm in patients with new-onset atrial flutter than in patients with new-onset atrial fibrillation. Relapse of atrial arrhythmia after cardioversion is associated with increased mortality.

Aged↗
PubMed2006

Patterns and predictors of warfarin use in patients with new-onset atrial fibrillation from the FRACTAL Registry.

Warfarin is underused for stroke prevention in atrial fibrillation (AF). Previous studies addressing this have lacked longitudinal assessment. This study sought to characterize contemporary warfarin use in new-onset AF and evaluate its change over time. It was hypothesized that AF recurrence has an important influence on warfarin use patterns. One thousand five adults from 17 centers in the United States and Canada were enrolled into a prospective observational registry after their first documented episodes of AF. Detailed demographic, clinical history, and management data were collected on all subjects at enrollment, including medication use. Patients were followed at regular intervals for interim events and changes in AF management. Warfarin use at baseline and last follow-up (mean 25 +/- 8 months) after enrollment was modeled using multivariate analysis. Initially, 65% of subjects were prescribed warfarin, but only 44% were taking it at 30 months. Even in "ideal" candidates for warfarin, the rate of warfarin prescription decreased from 70% at baseline to 50% at 30 months. Stroke risk factors, including hypertension, congestive heart failure, valvular heart disease, and previous stroke or transient ischemic attack were significant predictors of warfarin prescription at baseline. At last follow-up, the relation between AF recurrence and warfarin use (odds ratio 2.3, 95% confidence interval 1.6 to 3.1) was stronger than that for any individual stroke risk factor. In conclusion, predictors of warfarin use in patients with AF include AF recurrence and selected stroke risk factors. The discontinuation of warfarin in a large number of patients with AF over time is a cause for concern in light of data from recent clinical trials.

Aged↗
PubMed2006

The effect of patient sex on recurrence of atrial fibrillation following successful direct current cardioversion.

BACKGROUND: The effect of patient sex on recurrence of atrial fibrillation after a successful direct current cardioversion is unknown. METHODS: This prospective study included 773 patients (486 [63%] men and 287 [37%] women) undergoing successful direct current cardioversion of atrial fibrillation between May 2000 and July 2003. Patient characteristics at presentation were recorded. The primary end point was the time between cardioversion and the first documented recurrence of arrhythmia. RESULTS: At presentation, women were older and had a higher prevalence of hypertension and valvular disease compared with men. In addition, women had worse mechanical left atrial appendage function. Arrhythmia recurrence was more prevalent in women (50.0% at 1 year compared with 43.4% in men, and 75.8% at 2 years compared with 67.0% in men; P = .03). On the basis of multivariate analysis, patient sex was a significant predictor of arrhythmia recurrence. There was no significant difference in overall mortality between men and women. CONCLUSIONS: Women were more likely than men to have recurrence of atrial fibrillation after successful direct current cardioversion. Patient sex should be taken into account with other clinical factors when making the decision about cardioversion for atrial fibrillation.

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PubMed2006

Safety of expedited anticoagulation in patients undergoing transesophageal echocardiographic-guided cardioversion.

BACKGROUND: In patients undergoing transesophageal echocardiography-guided cardioversion, we evaluated the use and safety of an expedited in-hospital anticoagulation regimen that incorporates shorter-than-standard durations of precardioversion intravenous unfractionated heparin and postcardioversion bridging therapy with a low-molecular-weight heparin. METHODS: Adult patients who underwent successful transesophageal echocardiography-guided cardioversion for atrial fibrillation or atrial flutter between May 2000 and August 2003 were classified into 2 groups by duration of intravenous unfractionated heparin therapy (<24 h or > or =24 h) before transesophageal echocardiography and cardioversion. Safety end points evaluated included all-cause death, stroke or other thromboembolic events, and major bleeding complications within 1 month after successful cardioversion. RESULTS: The study population of 386 patients included 199 (52%) who received expedited intravenous unfractionated heparin (<24 h; minimum duration, <4 h) and 193 patients (50%) who were discharged on low-molecular-weight heparin therapy. The adverse event rates at 1-month follow-up were not significantly different between the 2 unfractionated heparin patient groups, and the rate of stroke among patients dismissed on low-molecular-weight heparin was less than 1%. No adverse events occurred among patients who received intravenous unfractionated heparin for less than 12 hours and who were dismissed on low-molecular-weight heparin bridging therapy. CONCLUSIONS: The use of an expedited heparin anticoagulation regimen in patients with atrial fibrillation or atrial flutter undergoing transesophageal echocardiography-guided cardioversion appears to be safe. Cardioversion can be performed as early as a few hours after initiation of intravenous unfractionated heparin, and bridging therapy with a low-molecular-weight heparin can be used after cardioversion until the international normalized ratio is therapeutic.

Aged↗
PubMed2005

High sensitivity C-reactive protein: a novel predictor for recurrence of atrial fibrillation after successful cardioversion.

OBJECTIVES: We sought to test the hypothesis that C-reactive protein (CRP) can predict the recurrence of atrial fibrillation (AF) after successful electrical cardioversion (CV). BACKGROUND: In patients with AF, CRP levels are predictive of immediate failure of CV. METHODS: We prospectively measured high-sensitivity CRP in 67 patients with AF or atrial flutter who underwent successful electrical CV. RESULTS: At one-month follow-up, 22 patients (33%) had recurrence of their arrhythmia. Arrhythmia recurrence was associated with significantly higher pre-CV CRP levels (odds ratio [OR] 1.84; 95% confidence interval [CI] 1.14 to 2.98; p = 0.013) even after adjusting for age (OR 2.22; 95% CI 1.25 to 3.93; p = 0.006), for gender (OR 1.89; 95% CI 1.16 to 3.09; p = 0.011), or duration of arrhythmia (OR 1.86; 95% CI 1.13 to 3.07; p = 0.015). On multivariate analysis, CRP was the only independent predictor of arrhythmia recurrence (OR 2.19; 95% CI 1.05 to 4.55; p = 0.036). CONCLUSIONS: Our data suggest that high levels of CRP are associated with an increased risk of recurrence of AF within one month. These data support the hypothesis that anti-inflammatory interventions may help in maintenance of normal sinus rhythm after CV. These data also may have implications for the identification of patients who are most likely to experience substantial benefit from CV therapy for AF.

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PubMed2005

Programmed ventricular stimulation in patients with idiopathic dilated cardiomyopathy and syncope receiving implantable cardioverter-defibrillators: a case series and a systematic review of the literature.

BACKGROUND: The role of programmed ventricular stimulation (PVS) in patients with idiopathic dilated cardiomyopathy (DCM) and syncope receiving implantable cardioverter-defibrillators (ICD) remains controversial. METHODS AND RESULTS: Between 1994 and July 2002, 20 patients with DCM and syncope underwent PVS and ICD implantation at the Onassis Cardiac Surgery Center or the Alexandra General Hospital. At PVS 10 patients had inducible sustained monomorphic ventricular tachycardia (SMVT), 3 patients had inducible sustained polymorphic ventricular tachycardia or ventricular fibrillation, and 7 patients had no inducible arrhythmia. The latter 7 patients received an ICD because of clinical occurrence of ventricular tachycardia (n=5) or fibrillation (n=2). Mean age was 55+/-14 years; 80% were men. During a mean follow-up of 2.8+/-2.3 years, 12 of the 20 patients received an appropriate shock. The incidence of appropriate shocks at 1 and 3 years was 69% and 84% in the inducible SMVT group, and 56% and 67% in the group without inducible SMVT (p=0.93, log rank test). Overall survival was similar in both groups (p=0.53). In a systematic review of the published literature 18 of 75 (24%) patients with DCM, syncope and a negative PVS had an appropriate ICD shock after a mean follow-up of 27 months. CONCLUSION: PVS has a limited role in risk stratification of patients with DCM and syncope.

Adult↗
PubMed2005

Role of permanent pacing to prevent atrial fibrillation: science advisory from the American Heart Association Council on Clinical Cardiology (Subcommittee on Electrocardiography and Arrhythmias) and the Quality of Care and Outcomes Research Interdisciplinary Working Group, in collaboration with the Heart Rhythm Society.

This advisory summarizes the current database on pacing modalities and algorithms used to prevent and terminate atrial fibrillation (AF). On the basis of the evidence indicating that ventricular pacing is associated with a higher incidence of AF in patients with sinus node dysfunction, a patient who has a history of AF and needs a pacemaker for bradycardia should receive a physiological pacemaker (dual chamber or atrial) rather than a single-chamber ventricular pacemaker. For patients who need a dual-chamber pacemaker, efforts should be made to program the device to minimize the amount of ventricular pacing when atrioventricular conduction is intact. Many pacemakers and implantable defibrillators have features designed to prevent AF and to terminate AF with rapid atrial pacing. The evidence to support their use is limited, although these algorithms appear to be safe and usually add little additional cost. For patients who have a bradycardia indication for pacing and also have AF, no consistent data from large randomized trials support the use of alternative single-site atrial pacing, multisite right atrial pacing, biatrial pacing, overdrive pacing, or antitachycardia atrial pacing. Even fewer data support the use of atrial pacing in the management of AF in patients without symptomatic bradycardia. At present, permanent pacing to prevent AF is not indicated; however, additional studies are ongoing, which will help to clarify the role of permanent pacing for AF.

Algorithms↗
PubMed2005

Device-based therapies for atrial fibrillation.

Ablation of the atrioventricular conduction system and pacemaker implantation is the preferred procedure for patients with atrial fibrillation (AF) in whom a rate control strategy has been selected but in whom rate-controlling medications are intolerable or ineffective. Selection of standard right ventricular (RV) pacing versus biventricular pacing is individualized, based on the degree and etiology of left ventricular dysfunction. Atrial-based pacing is clearly preferable to ventricular-based pacing in patients with sick sinus syndrome, because it leads to a reduction in the development of AF. Emerging evidence indicates that excess RV pacing is deleterious, increasing AF, heart failure, and possibly mortality. Therefore, physiologic pacing with minimization of RV pacing is desirable. Atrial pacing algorithms that increase the frequency of atrial pacing have shown modest efficacy in the prevention of AF. Use of atrial pacing algorithms is reasonable for patients with a history of AF and standard bradycardia indications for permanent pacing in whom maintenance of sinus rhythm is desirable. Studies assessing novel and multiple site atrial pacing therapies have mixed results, without compelling evidence of clinically important benefit. The exceptions are biatrial and right atrial overdrive pacing immediately after cardiac surgery. Several studies have shown effective suppression of postoperative AF with their use. Device therapy (eg, atrial antitachycardia pacing and defibrillation) for the termination of AF is effective in reducing arrhythmia burden. However, improvement in clinically relevant end points is not established and indications are not clearly defined. If a patient lacks an indication for an implantable cardioverter-defibrillator, we do not offer atrial defibrillation as a treatment option. Atrial arrhythmias may be better prevented by programming to avoid ventricular pacing than by specific atrial interventions.

Journal Article↗
PubMed2005

Comparative efficacy of monophasic and biphasic waveforms for transthoracic cardioversion of atrial fibrillation and atrial flutter.

BACKGROUND: Transthoracic cardioversion fails to restore sinus rhythm in 6% to 33% of patients with atrial fibrillation. This study sought to determine the relative efficacy of biphasic waveforms compared with monophasic waveforms in the treatment of atrial arrhythmias. METHODS: A total of 912 patients underwent 1022 transthoracic cardioversions between May 2000 and December 2001. A monophasic damped sine waveform was used in the first 304 cases, and a rectilinear biphasic defibrillator was used in the next 718 cases. RESULTS: Use of a biphasic waveform was associated with 94% success in conversion to sinus rhythm compared with 84% with a monophasic waveform (P < .001). The cumulative energy required to restore sinus rhythm was lower with biphasic shocks in both atrial fibrillation and atrial flutter groups (554 +/- 413 J for monophasic vs 199 +/- 216 J for biphasic shocks in the atrial fibrillation group, P < .001; 251 +/- 302 J vs 108 +/- 184 J, respectively, in the atrial flutter group, P < .001). In a multivariate analysis, use of a biphasic shock was associated with a 3.9-fold increase in success of cardioversion. CONCLUSION: When used to cardiovert atrial arrhythmias, the rectilinear biphasic waveform was associated with higher success rates and lower cumulative energies than the monophasic damped sine waveform.

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PubMed2005

Prospective, randomized comparison of two biphasic waveforms for the efficacy and safety of transthoracic biphasic cardioversion of atrial fibrillation.

OBJECTIVES: The purpose of this study was to determine if there is a difference in commercially available biphasic waveforms. BACKGROUND: Although the superiority of biphasic over monophasic waveforms for external cardioversion of atrial fibrillation (AF) is established, the relative efficacy of available biphasic waveforms is less clear. METHODS: We compared the effectiveness of a biphasic truncated exponential (BTE) waveform and a biphasic rectilinear (BR) waveform for external cardioversion of AF. Patients (N = 188) with AF were randomized to receive transthoracic BR shocks (50, 75, 100, 120, 150, 200 J) or BTE shocks (50, 70, 100, 125, 150, 200, 300, 360 J). Shock strength was escalated until success or maximum energy dose was achieved. If maximum shock strength failed, patients received the maximum shock of the opposite waveform. Analysis included 141 patients (71 BR, 70 BTE; mean age 66.5 +/- 13.7. Forty-seven randomized patients were excluded because of flutter on precardioversion ECG upon blinded review (n = 25), presence of intracardiac thrombus (n = 7), or protocol deviation (n = 15). Groups were similar with regard to clinical and echocardiographic characteristics. RESULTS: The success rate was similar for the two waveforms (93% BR vs 97 BTE, P = .44), although cumulative selected and delivered energy was less in the BTE group. Only AF duration was significantly different between successful and unsuccessful patients. No significant complications occurred. CONCLUSIONS: Biphasic waveforms were very effective in transthoracic cardioversion of AF, and complication rates were low. No significant difference in efficacy was observed between BR and BTE waveforms. Impedance was not an important determinant of success for either biphasic waveform.

Aged↗
PubMed2005

Therapy Insight: interactions between atrial fibrillation and obstructive sleep apnea.

Atrial fibrillation (AF) and obesity are coinciding epidemics. Obstructive sleep apnea (OSA) correlates directly with obesity and is highly prevalent among middle-aged adults. Emerging evidence supports a strong association between AF and OSA. The rate of AF among patients with OSA is low but is nevertheless higher than that in the general population. The prevalence of OSA among patients with AF is strikingly high-at least 32% and possibly as high as 49%-although differences in the AF populations studied and the criteria used to diagnose OSA have prevented more accurate measurement of this rate. Data in focused populations at risk of AF show that OSA increases the frequency and recurrence of AF. These findings cannot, however, be reliably generalized to the larger OSA population. Although the available information is limited, treatment of OSA, particularly with continuous positive airway pressure, seems to substantially reduce the frequency of AF. If true, this approach would provide a safe and noninvasive therapy for some patients with AF. Randomized controlled trials are necessary to rigorously answer this question. Many data have been obtained from studies with focuses other than the direct relationship between OSA and AF. Studies carefully designed to investigate the relevant issues are now needed.

Atrial Fibrillation↗