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Anne M Gillis

Publications and source records attributed to Anne M Gillis.

36 records · Page 2Linked to original sources
PubMed2004

Clinical trials of pacing for maintenance of sinus rhythm.

Several prospective randomized clinical trials have demonstrated that atrial-based pacing prevents the development of paroxysmal and persistent atrial fibrillation (AF) in patients with symptomatic bradycardia as the indication for a pacemaker. The greatest benefit appears to be in patients with sinus node dysfunction as the primary indication for pacing. Studies of site specific atrial pacing have not shown a consistent benefit for prevention of AF. A number of prospective studies have been undertaken to assess the role of selective atrial pacing algorithms designed for prevention of AF. These studies suggest that these AF pace prevention algorithms have modest to minimal incremental benefit compared to atrial based pacing alone for the prevention of AF. Atrial antitachycardia pacing (ATP) algorithms have been incorporated into some pacemakers and defibrillators. Overall, atrial ATP therapy has not been shown to substantially reduce the burden of AF in one randomized trial. However, there are subsets of patients e.g. those with atrial flutter as well as AF who are likely to benefit from this therapy.

Algorithms↗
PubMed2004

Accuracy of atrial tachyarrhythmia detection in implantable devices with arrhythmia therapies.

The clinical application of atrial tachyarrhythmia (AT) episode data stored by implantable devices is presently limited by the high proportion of inappropriate detection. We quantified the percentage of inappropriate AT detection in two implantable devices with AT diagnostics and therapies via meta-analysis of stored AT episodes from a number of clinical trials. The AT500 and GEM III AT, contain dual chamber logic to discriminate AT from ventricular tachycardia and far-field R wave (FFRW) oversensing using dual chamber bipolar electrograms. A subset of data from four clinical trials of 1,142 patients was considered. Manual analysis was performed on 21,553 stored episodes with atrial EGM and marker channel from 409 patients with stored episodes and the market-released device detection configuration. The percentage of episodes with inappropriate detection and termination was evaluated and compared between septal and nonseptal lead locations. The percentage of inappropriately detected episodes receiving ATP therapy was also determined. The percentage of episodes appropriately detected and the percentage of net episode duration (i.e., burden) recorded by the device were also determined from a separate analysis of 24-hour Holter recordings from a subset of 40 patients from one trial. Adjusted estimates of the percentage of appropriate [corrected] detection were 95.3% (93.5-96.7; 95% CI) for AT500 and 95.7% (84.3-98.9) for GEM III AT. Inappropriate detection was primarily due to FFRW oversensing or brief runs of premature atrial contractions (PACs). The device detected 100% of the sustained atrial arrhythmia episodes and 95.3% (range 76.1-99.9) of the net AT duration observed on the Holter recordings. AT detection was not influenced by atrial lead location. Appropriate detection of normal sinus rhythm at episode termination was 83.7% (80.7-86.3) for AT500 and 92.1% (84.5-96.2) for GEM III AT. Accurate detection and discrimination of FFRWs validates the reliability of AT diagnostic data and decreases the risk of inappropriate device therapy.

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PubMed2003

Are lipid-lowering drugs also antiarrhythmic drugs? An analysis of the Antiarrhythmics versus Implantable Defibrillators (AVID) trial.

OBJECTIVES: This study sought to evaluate the antiarrhythmic effects of lipid-lowering drug therapy as assessed by ventricular tachyarrhythmia (ventricular tachycardia [VT]/ventricular fibrillation [VF]) recurrences recorded by an implantable cardioverter defibrillator (ICD) in patients with atherosclerotic heart disease (ASHD). BACKGROUND: Randomized trials of lipid-lowering drugs suggest reduction of sudden death (SD) in patients with ASHD. Because SD is usually secondary to VT/VF, this observation suggests that lipid-lowering therapy has antiarrhythmic effects. METHODS: The probability of VT/VF recurrence in patients with ASHD treated with an ICD in the Antiarrhythmics Versus Implantable Defibrillators (AVID) trial who did not receive lipid-lowering drug therapy (n = 279) was compared with that in patients who received early and consistent lipid-lowering therapy (n = 83). In addition, all-cause mortality and cardiac mortality of all patients in the AVID trial with ASHD who did not receive lipid-lowering therapy (n = 564) were compared with that of those who received early and consistent lipid-lowering therapy (n = 149). RESULTS: Using multivariate analyses, lipid-lowering therapy was associated with a reduction in the relative hazard for VT/VF recurrence of 0.40 (95% confidence interval [CI] 0.15 to 0.58) (adjusted p = 0.003) in the ICD subgroup. Lipid-lowering therapy was also associated with a reduction in the relative hazard for all-cause mortality of 0.36 (95% CI 0.15 to 0.68) (adjusted p = 0.03) and a reduction in the relative hazard for cardiac mortality of 0.39 (95% CI 0.16 to 0.78) (adjusted p = 0.04) in the larger study population. CONCLUSIONS: In patients with ASHD who have received an ICD, lipid-lowering therapy is associated with reduction in the probability of VT/VF recurrence, suggesting that part of the benefit of lipid-lowering therapy may be due to an antiarrhythmic effect.

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PubMed2003

New indications for pacing.

This article reviews developments in four areas: single- versus dual-chamber pacing, pacing for prevention of atrial fibrillation (AF), pacing for the treatment of neuromediated syncope, and pacing in patients with congestive heart failure. Large, randomized clinical trials comparing physiologic and ventricular pacing in different pacemaker populations have demonstrated that physiologic pacing does prevent AF but does not reduce cardiac mortality or stroke. The benefit for prevention of AF appears to be in patients with sinus node disease as the primary indication for pacing. Selective atrial pacing algorithms designed for the prevention of AF have not been shown to substantially reduce the overall burden of AF. Cardiac pacing has been shown to have a moderate benefit in the treatment of neuromediated syncope. Cardiac resynchronization therapy is emerging as a promising new treatment for heart failure. Long-term studies report that it improves quality of life and functional capacity, and reduces hospitalizations for heart failure. The impact of this therapy on mortality awaits the results of ongoing studies.

Atrial Fibrillation↗
PubMed2003

Selection of pacing mode after interruption of atrioventricular conduction for atrial fibrillation: observations from the PA3 clinical trial.

The optimal pacing mode for patients with paroxysmal atrial fibrillation (AF) following AV junction ablation remains the subject of some debate. Recent clinical trials have not demonstrated a superior advantage of maintenance of sinus rhythm over the rate control approach. However, clinical trials in pacemaker populations have demonstrated that physiologic pacing reduces the probability of paroxysmal and persistent AF compared to ventricular pacing. In the second phase of the PA(3) study, patients were randomized to DDDR versus VDD pacing in a cross over study design. Of the 67 patients randomized, 42% developed permanent AF within one year following ablation. AF frequency and burden increases early following AV junction ablation suggesting that ventricular pacing even in an atrial synchronous mode promotes AF. Given the high probability of permanent AF developing early following ablation, VVIR pacing appears to be the appropriate pacing mode for symptomatic patients undergoing total AV junction ablation.

Atrial Fibrillation↗
PubMed2003

Atrial pacing therapies for prevention of atrial fibrillation in patients with implantable defibrillators.

Atrial fibrillation (AF), atrial flutter and atrial tachycardia (AT) occur frequently in patients following implantation of an implantable cardioverter defibrillator (ICD) for the treatment of ventricular tachyarrhythmias. Some new generation ICDs have incorporated atrial antitachycardia pacing therapy (ATP) and atrial pacing algorithms designed specifically for the prevention of AF. In the GEM III AT clinical evaluation, atrial ATP efficacy for termination of AF and AT was assessed. Overall ATP efficacy for AF/AT, based on device classification, was 40% when adjusted using the Generalized Estimating Equations to account for correlated data that arises from utilizing multiple episodes in some patients. However, many episodes of AF/AT were noted to terminate within 10 minutes of onset. Applying a more conservative definition of efficacy, termination within 20 sec of delivery of the last atrial ATP, efficacy for termination of AF/AT was 26%. 50 Hz burst pacing was shown to have minimal efficacy for termination of AF and modest incremental benefit following ramp or burst pacing therapies for AT. These observations provide a more realistic expectation of the value of atrial ATP in the ICD population with AF. Atrial ATP terminates some episodes of AT but previously reported efficacy rates of 40-50% are exaggerated and in part reflect spontaneous terminations of some AF/AT episodes.

Algorithms↗
PubMed2003

Paced QT dispersion and QT morphology after radiofrequency atrioventricular junction ablation: impact of left ventricular function.

Catheter ablation of the atrioventricular junction (AVJ) is a widely accepted treatment for drug refractory atrial fibrillation. Unfortunately, there have been some reports of pause dependent ventricular arrhythmias associated with QT interval prolongation, mainly in patients with reduced LV function. The present investigation evaluates the association of LV function with QT dispersion in response to a sudden rate drop. ECGs were' recorded on 20 patients (13 with normal LV function) on the day following AVJ ablation while paced at a range of ventricular rates (40-120 beats/min), and during a sudden drop from 80 to 40 beats/min. The maximum QT interval (QTmax), minimum QT interval (QTmin), and QT interval dispersion (QTdisp) were compared. In both groups, the QTmax and QTmin increased at slower paced heart rates while the QTdisp did not change. In response to a sudden rate drop from 80 to 40 beats/min, the QTmax increased in both groups of LV function (trend), while the QTmin increased in those with normal LV function (24 +/- 22 ms), but not in those with reduced LV function (0 +/- 14 ms; P = 0.01). Consequently, the QTdisp increased significantly in those with reduced LV function (31 +/- 23 ms) but not in normal LV function (-5 +/- 29 ms; P = 0.01). Morphological QTU changes developed following the sudden rate drop in 67% of the reduced LV versus 8% of the normal LV (P = 0.02) function groups. Following AVJ ablation, QTdisp increased during a sudden rate drop in patients with reduced LV function, but not in patients with normal LV function.

Atrial Fibrillation↗
PubMed2003

Clinical and electrophysiologic predictors of ventricular tachyarrhythmia recurrence in patients with implantable cardioverter defibrillators.

INTRODUCTION: Not all patients experience recurrent sustained ventricular tachyarrhythmias after placement of an implantable cardioverter defibrillator (ICD). We evaluated the clinical and electrophysiologic predictors of ventricular tachycardia (VT) and ventricular fibrillation (VF) recurrence following ICD implantation. METHODS AND RESULTS: Consecutive patients (n = 133) underwent 4 +/- 3 serial electrophysiologic studies (EPS) over 50 +/- 26 months following ICD implantation. Sustained VT/VF could always be induced during follow-up EPS in 49 patients; sustained VT/VF was sometimes induced during follow-up EPS in 47 patients; and sustained VT/VF could never be induced during follow-up EPS in 37 patients. Spontaneous VT/VF requiring ICD therapy occurred in 107 patients during follow-up. Patients with sustained VT/VF that was always inducible or sometimes inducible during follow-up experienced more frequent episodes of VT/VF following ICD implant (20.5, 95% CI 12.7-33.0; and 17.8, 95% CI 11.3-28.1 episodes/patient respectively; vs 3.0, 95% CI 2.0-4.6 episodes/patient for patients with VT/VF never induced, P < 0.001). Inducibility of sustained VT/VF post-ICD implant (P < 0.001) and sustained VT as the presenting arrhythmia (P = 0.02) were independent predictors of spontaneous VT/VF recurrence. CONCLUSION: Reproducibly inducible VT/VF following ICD implantation predicts a high probability of VT/VF recurrence and identifies a cohort of patients who experience frequent episodes of VT/VF over time. Persistent noninducibility of sustained VT/VF identifies a group of patients who experience no or very few episodes of VT/VF recurrence.

Aged↗
PubMed2003

Total atrioventricular nodal ablation increases atrial fibrillation burden in patients with paroxysmal atrial fibrillation despite continuation of antiarrhythmic drug therapy.

INTRODUCTION: Total atrioventricular nodal (TAVN) ablation and pacing is an accepted and safe treatment for patients with drug-refractory paroxysmal atrial fibrillation (AF). Many patients develop permanent AF within the first 6 months after TAVN ablation. This usually is ascribed to the cessation of antiarrhythmic drug therapy. We hypothesized that TAVN ablation itself creates an atrial substrate prone to AF. METHODS AND RESULTS: Patients participating in the Atrial Pacing Periablation for Paroxysmal Atrial Fibrillation (PA3) study who remained on stable antiarrhythmic drug therapy throughout follow-up were included in this analysis. AF burden and the development of persistent AF in the preablation period were compared to two consecutive postablation periods. Echocardiographic changes also were evaluated. Twenty-two patients remained on stable drug therapy (9 men and 13 women, age 59 +/- 3 years). One patient developed persistent AF preablation compared to 10 postablation (P < 0.05). AF burden preablation was 3.0 +/- 1.2 hours/day and increased to 10.4 +/- 2.2 hours/day and 11.8 +/- 2.3 hours/day in the two postablation follow-up periods (P < 0.05). In patients with fractional shortening (FS) >30% prior to ablation, FS decreased significantly from 39.4% +/- 1.3% to 36.4%+/- 1.7% (P < 0.05). In contrast, in patients with a FS < or =30% prior to ablation, FS increased from 27% +/- 0.8% to 33.6 +/- 1.7% (P < 0.05). CONCLUSION: TAVN ablation increases AF burden and facilitates the development of persistent AF in patients with paroxysmal AF despite the continuation of antiarrhythmic drugs. Loss of AV and/or interventricular synchrony may lead to altered cardiac hemodynamics resulting in atrial stretch and increasing AF burden.

Adult↗
PubMed2003

Randomized controlled trial of fixed rate versus rate responsive pacing after radiofrequency atrioventricular junction ablation: quality of life, ventricular refractoriness, and paced QT dispersion.

INTRODUCTION: Ablation of the AV junction is a widely accepted treatment of drug-refractory atrial fibrillation. Long-term pacing of the right ventricular (RV) apex following AV junction ablation can result in adverse cardiac remodeling. However, anecdotal studies report that pacing too slowly following AV junction ablation was associated with propensity to sudden cardiac death. The aim of this study was to provide information about the balance between measures of quality of life versus measures of electrical remodeling achieved by pacing with different rate modalities in a randomized pilot clinical trial. METHODS AND RESULTS: Patients with permanent atrial fibrillation were randomized to VVI (80 beats/min) versus VVIR (minimum rate 80 beats/min), whereas patients with paroxysmal atrial fibrillation were randomized to DDI versus DDDR pacing at discharge from hospital. Serially, measurements of exercise capacity, quality of life, cycle length dependence of QT dispersion (QTdisp), RV refractoriness, and the incidence of nonsustained ventricular tachycardia were made in 28 patients over a 6-month follow-up period. Time-dependent increases in QTdisp were observed in patients randomized to the rate responsive mode (RR-ON) but only when paced at 40 beats/min. This was paralleled by time-dependent increases in RV refractoriness (270 +/- 11 ms at baseline to 302 +/- 5 ms at 6 months) in patients with RR-ON. RR-ON also was associated with trends to an increasing incidence of episodes of nonsustained ventricular tachycardia and worsening of some measures of quality of life. Exercise capacity was not substantially different in the randomized groups. CONCLUSION: Rate responsive pacing results in electrical remodeling of the ventricle following AV junction ablation, but exercise capacity was similar in groups with RR-ON or RR-OFF.

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PubMed2003

Guidelines for implantable cardioverter defibrillator follow-up in Canada: a consensus statement of the Canadian Working Group on Cardiac Pacing.

A survey on the follow-up practices of patients with implantable cardioverter defibrillators (ICDs) in Canada was conducted by the Canadian Working Group on Cardiac Pacing in 1999. The survey identified the need for national guidelines. The present guidelines for ICD follow-up represent a consensus statement of the Canadian Working Group on Cardiac Pacing. They recommend that patients be assessed before hospital discharge, at two to 12 weeks following implantation, six months after implantation, and at a minimum of every six months thereafter. More frequent assessments may be required for some patients depending on associated cardiovascular problems and specific ICD devices. A typical follow-up visit should include a targeted cardiovascular assessment, interrogation of the ICD, review of telemetered data, assessment of the underlying rhythm, pacing and sensing thresholds, lead impedance and appropriate reprogramming of ICD parameters to optimize device function and longevity.

Cardiac Pacing, Artificial↗
PubMed2002

Safety and efficacy of advanced atrial pacing therapies for atrial tachyarrhythmias in patients with a new implantable dual chamber cardioverter-defibrillator.

OBJECTIVES: This study evaluated the safety and efficacy of atrial pacing therapies for the treatment and prevention of atrial tachycardia (AT) or atrial fibrillation (AF) in a new dual chamber implantable cardioverter defibrillator (ICD). BACKGROUND: Patients with an ICD may also experience AT or AF that is amenable to pace termination. METHODS: The efficacy of atrial antitachycardia pacing (ATP) therapies for atrial tachycardia or atrial fibrillation (AT/AF) was determined in 151 patients after implantation of a GEM III AT ICD (Medtronic Inc., Minneapolis, Minnesota). The percentage of episodes successfully terminated was adjusted for multiple episodes per patient. RESULTS: A total of 717 of 728 (96%) episodes classified as AT or AF were judged to be appropriate detections. By device classification, atrial ATP terminated 187 of 383 (40% adjusted) episodes classified as AT compared with 65 of 240 episodes classified as AF (26% adjusted, p = 0.013). Atrial Ramp or Burst+ ATP terminated 184 of 378 episodes of AT (39% adjusted), whereas 50-Hz Burst pacing therapy terminated only 12 of 109 episodes of AT (12% adjusted) and 65 of 240 episodes of AF (26% adjusted). If efficacy was defined as termination of AT/AF within 20 s of delivery of the pacing therapy, ATP therapies terminated 139 of 383 (32% adjusted) episodes of AT compared with 34 of 240 episodes of AF (15% adjusted, p = 0.003). Efficacy was dependent on AT cycle length. Frequent transitions between AT and AF predicted inefficacy of atrial ATP (p < 0.001). Ventricular proarrhythmia secondary to atrial ATP was not observed. CONCLUSIONS: Atrial ATP therapies terminate many episodes of AT without ventricular proarrhythmia. The addition of 50-Hz Burst pacing has minimal efficacy for AT/AF.

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PubMed2002

Precordial QT dispersion does not predict inducibility of ventricular tachyarrhythmias at post-revascularization electrophysiologic study.

OBJECTIVES: We tested the hypothesis that revascularization would decrease QT interval dispersion and that QT interval dispersion would predict the outcome of the electrophysiologic study following revascularization. BACKGROUND: QT interval dispersion may be a measure of the inhomogeneity of ventricular repolarization. The value of the QT interval dispersion for predicting inducibility of ventricular tachyarrhythmias (VT) during electrophysiologic studies after coronary artery revascularization in patients with hemodynamically significant VT is unknown. METHODS AND RESULTS: QT interval dispersions were measured from electrocardiograms recorded before and after coronary artery revascularization, but before an electrophysiologic study during the same hospitalization. Fifty-six patients (93% male, 65.1 +/- 9.6 years) were studied. QT interval dispersion decreased significantly following revascularization from 69 +/- 31 ms to 53 +/- 23 ms (p=0.002). Inducibility of VT could not be predicted by the QT interval dispersion following revascularization (50 +/- 30 ms in patients with VT induced vs. 58 +/- 25 ms in patients without VT induced at electrophysiologic study; p=0.2). The change in QT interval dispersion with revascularization (-15 +/- 33 ms vs. -17 +/- 46 ms; p=0.9) could not predict VT inducibility. Actuarial survival after 80 months follow-up was similar in the patients in whom VT was induced (82%) and those patients in whom VT was not induced (83%; p=NS). CONCLUSIONS: Coronary artery revascularization decreased QT interval dispersion in patients with hemodynamically significant VT, but QT interval dispersion was not predictive of inducibility of VT at follow-up electrophysiologic study. Actuarial survival was similar in patients in whom VT was induced and patients in whom VT was not induced.

Aged↗
PubMed2002

Atrial fibrillation after DDDR pacemaker implantation.

INTRODUCTION: Newer implantable pulse generators have data storage capabilities that permit detection of multiple episodes of atrial fibrillation (AF). This study evaluated the clinical predictors and time course of AF development in a general pacemaker population. METHODS AND RESULTS: Patients (n = 231) received DDDR pacemakers with features that permit detection and storage of information about the date, time of onset, and duration of multiple, sequential episodes of AF. Patients were followed for 718+/-383 days. Time to first occurrence of AF, interval between first and second episode of AF, and total AF burden were determined at each follow-up visit. AF occurred more often in patients (68%) with sinus node disease than in patients with AV block (37%; P < 0.001). Time to first occurrence of AF was 21.2 days (95% confidence interval [CI] 14.7 to 30.6 days) after pacemaker implantation. AF burden initially decreased significantly in patients (0.8 hours/day, 95% CI 0.7 to 0.9 at 8 weeks after implant vs 0.6 hours/day, 95% CI 0.4 to 0.8 at 12 months after implant; P = 0.005) but then increased significantly during long-term follow-up (2.0 hours/day, 95% CI 1.0 to 3.7 at 48 months after implant; P = 0.008). The long-term increase in AF burden was seen predominantly in patients with sinus node disease. A prior history of AF and the duration of follow-up were independent predictors of AF occurrence. CONCLUSION: AF develops frequently after dual-chamber pacemaker implantation. AF burden increases progressively over the long term.

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PubMed2002

Effect of surgical revascularization in patients with coronary artery disease and ventricular tachycardia or fibrillation in the Antiarrhythmics Versus Implantable Defibrillators (AVID) Registry.

BACKGROUND: Patients who undergo resuscitation from near-fatal ventricular arrhythmias often have significant coronary artery disease, and revascularization has been shown to reduce myocardial ischemia and cardiac arrest episodes in this patient population. The magnitude of benefit attributed to revascularization has varied by study, and the use of adjunct implantable cardioverter defibrillator (ICD) therapy has not been well-characterized. METHODS AND RESULTS: The Antiarrhythmics Versus Implantable Defibrillators (AVID) registry included 3117 patients with life-threatening ventricular arrhythmias, of whom 2321 (77%) had documented coronary artery disease and 281 (17%) underwent a coronary artery bypass grafting revascularization procedure after the index event. Patients who underwent a revascularization procedure were younger, had a lower incidence rate of prior myocardial infarction and ventricular arrhythmia, had a higher left ventricular ejection fraction, had less congestive heart failure, and were more likely to have had ventricular fibrillation as the presenting arrhythmia. Patients who underwent revascularization had a better survival rate than did those who did not undergo such a procedure after the index event, and adjustment for differing baseline patient covariates did not alter the relative survival rate benefit. Further, ICD implantation offered a similar survival rate advantage to those patients in the AVID registry with coronary artery disease independent of revascularization. CONCLUSION: Coronary revascularization in the AVID registry patients with coronary artery disease effected a survival rate benefit that was not attributable to differences in baseline patient characteristics. The benefit of ICD on patient survival rate was not attenuated by a revascularization procedure.

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PubMed2002

Antitachycardia pacing therapies and arrhythmia monitoring diagnostics for the treatment of atrial fibrillation.

The case of a patient with frequent episodes of atrial fibrillation that organizes into atrial flutter following implantation of a dual chamber, rate adaptive pacemaker is reported. The atrial flutter was effectively pace-terminated following activation of the atrial antitachycardia pacing therapies in the pacemaker. This resulted in a decrease in atrial fibrillation burden over time. The present case also illustrates the value of diagnostic data retrieved from pacemakers for monitoring atrial fibrillation frequency over time and evaluating the efficacy of pacing and drug therapy.

Aged↗