Publications (88)461.33 Total impact
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Article: Canadian Cardiovascular Society/Canadian Heart Rhythm Society Joint Position Statement on the Use of Remote Monitoring for Cardiovascular Implantable Electronic Device Follow-up.
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ABSTRACT: Remote monitoring (RM) is a form of telemedicine technology that permits implanted pacemakers and implantable cardioverter-defibrillators to transmit diagnostic information for review by health care professionals without patients needing to visit the device follow-up clinic. A bedside transmitter in the patient's home conveys the device data using standard telecommunication protocol to a protected internet-accessible RM data server, which authorized health care professionals can access at any time using standard web browser software. Evidence indicates it can accelerate identification of clinical events and potential device problems. RM raises important medicolegal issues concerning the protection of a patient's rights and the safeguarding of patient health information related to the collection, storage, and use of patient device information that must be addressed by follow-up centres. This position statement recommends that remote monitoring be available at all device follow-up clinics as an integral part of the standard of care of device patients and also provides helpful advice to centres for the proper design, implementation, and integration of a remote monitoring system into the clinic.The Canadian journal of cardiology 03/2013; · 3.36 Impact Factor -
Article: Failure Rate of the Riata Lead Under Advisory: A report from the CHRS Device Committee.
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ABSTRACT: BACKGROUND: A unique form of lead failure has been described in the Riata (8Fr) and Riata ST (7Fr) silicone defibrillation lead; degradation of the outer insulation resulting in externalization of conductor cables. OBJECTIVE: To assess rates of lead revision due to lead failure in Riata leads affected by the Riata advisory. METHODS: Nineteen ICD implant and follow up centers were surveyed RESULTS: As of March 1, 2012, there were 5043 known affected leads implanted in Canada. Data on 4358 (86.4%) leads were obtained; 65.3% of these were Riata (8Fr), 32.4% Riata ST (7Fr). The median time from implant to last follow-up was 5 years. Electrical abnormalities were reported in 4.6% of affected leads; 8.0% of these were found to have concomitant radiographic evidence of externalization. The rate of electrical failure was higher in the 8 French (5.2%) versus 7 French (3.3%) leads (p=0.007). Over-sensing with or without inappropriate shocks was reported in 39.8% of leads with confirmed failure. Abnormally high or low impedance values (29.9%) and elevated pacing capture thresholds (43.8%) were frequently reported. One death (0.5%) attributed to lead failure was reported. Among the leads that were replaced, 21% were extracted. Two major complications (1.0%) were attributed to extraction of these leads. CONCLUSION: The overall rate of lead failure in the Riata (8Fr) and Riata ST (7Fr) lead is higher than previously reported using passive surveillance data. The impact of recent advisories related to these leads is not yet apparent.Heart rhythm: the official journal of the Heart Rhythm Society 01/2013; · 4.56 Impact Factor -
Article: Discerning the Incidence of Symptomatic and Asymptomatic Episodes of Atrial Fibrillation Before and After Catheter Ablation (DISCERN AF): A Prospective, Multicenter Study.
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ABSTRACT: BACKGROUND The DISCERN AF study (Discerning Symptomatic and Asymptomatic Episodes Pre and Post Radiofrequency Ablation of Atrial Fibrillation) monitored atrial fibrillation (AF) using an implantable cardiac monitor (ICM) to assess the incidence and predictors of asymptomatic AF before and after catheter ablation. METHODS Patients with symptomatic AF underwent implantation of an ICM with an automated AF detection algorithm 3 months before and 18 months after ablation. Patients kept a standardized diary to record symptoms of arrhythmia, and ICM data were downloaded every 3 months. All episodes were blindly adjudicated and correlated with the diary. Asymptomatic recurrences were ICM episodes of 2 minutes or longer with no associated diary symptoms. RESULTS Fifty patients had 2355 ICM episodes. Of these, 69.0% were true AF/atrial flutter (AFL)/atrial tachycardia (AT); 16.0%, sinus with extrasystoles; 11.0%, artifact; and 4.0%, sinus arrhythmia. Total AF/AFL/AT burden was reduced by 86% from a mean (SD) of 2.0 (0.5) h/d per patient before to 0.3 (0.2) h/d per patient after ablation (P < .001), and 56.0% of all episodes were asymptomatic. The ratio of asymptomatic to symptomatic AF episodes increased after ablation from 1.1 to 3.7 (P = .002). By symptoms alone, 29 of 50 patients (58%) were free of AF/AFL/AT after ablation compared with 23 of 50 (46%) using ICM-detected AF/AFL/AT recurrence. Asymptomatic episodes were more likely AFL/AT and were significantly shorter and slower, with lower heart rate variability. However, the postablation state was the strongest independent predictor of asymptomatic AF. CONCLUSIONS The ratio of asymptomatic to symptomatic AF episodes increased from 1.1 before to 3.7 after ablation. Postablation state is the strongest predictor of asymptomatic AF. Symptoms alone underestimate postablation AF burden, with 12% of patients having asymptomatic recurrences only. TRIAL REGISTRATION clinicaltrials.gov Identifier: NCT00745706.Archives of internal medicine 12/2012; · 11.46 Impact Factor -
Article: Postprocedural neuropathy after atrial fibrillation ablation.
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ABSTRACT: PURPOSE: Access-related neuropathy after atrial fibrillation (AF) ablation is underappreciated. We intend to describe the incidence, management, and prognosis of postprocedural neuropathy after AF ablation. METHODS: We performed a retrospective analysis of all consecutive patients with postprocedural neuropathy who underwent AF ablation in three high-volume tertiary care hospitals between January 2007 and April 2011. RESULTS: Of the 3,128 patients who underwent AF ablation during the study period, 25 (0.8 %) patients had postprocedural neuropathy and were included in the current study. Mean age was 58.5 ± 11.5 years with 18 (72 %) being males and 14 (56 %) having paroxysmal AF. Ulnar nerve, lateral femoral cutaneous nerve manifesting as meralgia paresthetica, and femoral nerve were involved in 5 (20 %), 13 (54 %), and 7 (26 %) of the patients, respectively. Majority of neuropathies were associated with periprocedural hematomas (19, 76 %), and a quarter (19/72, 26 %) of all hematomas were associated with neuropathy. Initial treatment included warm and cold compresses followed by nonsteroidal anti-inflammatory and narcotic pain medications. In addition to the above regimen, in some patients (11, 44 %), oral gabapentin was used and it was associated with a shorter time to symptom resolution (9.4 vs. 14.1 days, p = 0.007). All patients were symptom free within 90 days of the procedure. CONCLUSION: Postprocedural neuropathy after AF ablation is rare and is frequently associated with a periprocedural hematoma. Patients typically become symptom free within 90 days of the procedure, and gabapentin may have a role in earlier symptom resolution.Journal of Interventional Cardiac Electrophysiology 12/2012; · 1.17 Impact Factor -
Article: Approaches to empiric ablation of slow pathway: results from the Canadian EP web survey.
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ABSTRACT: Dual atrioventricular nodal physiology (DAVNP) is a frequent finding in patients with suspected or documented supraventricular tachycardia (SVT). Empiric slow pathway ablation (ESPA) is sometimes performed in patients with DAVNP without inducible SVT at the time of electrophysiological study. Evidence to guide this practice in the adult population is limited. This study was aimed to assess the practice of ESPA by adult electrophysiologists in Canada. All Canadian interventional electrophysiologists (n = 81) were invited to complete a web-based questionnaire assessing their practice of ESPA in patients with suspected and documented SVT. Operator experience, reimbursement models, diagnostic, and treatment decisions regarding ESPA were assessed with case scenarios. Forty-one responses (50 %) were obtained. Ninety-five percent of the responders stated that the evidence for ESPA is lacking or limited. Responders were more likely to perform ESPA in the setting of non-inducible SVT when there was documentation of the clinical arrhythmia (64 vs. 31 % (p = 0.017)). The threshold to perform ESPA was highly variable. Longer time in practice (r = 0.38, p = 0.017) and less perceived complications with ESPA (r = 0.31, p = 0.05) were correlated with the practice of ESPA, whereas length of ablation waiting lists (r = -0.15, p = 0.38), number of procedures performed per day (r = 0.11, p = 0.51) and type of reimbursement (p = 0.24) were not associated with the practice of ESPA. The perceived complication rate with ESPA was <1 %. Variability in the practice of ESPA in cases of non-inducible SVT exists. Documentation of the clinical arrhythmia, operator experience, and perceived low complication rates positively influence this practice.Journal of Interventional Cardiac Electrophysiology 07/2012; 35(2):183-7. · 1.17 Impact Factor -
Article: Anticoagulation Management Pre- and Post Atrial Fibrillation Ablation: A Survey of Canadian Centres.
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ABSTRACT: BACKGROUND: Anticoagulation in patients undergoing atrial fibrillation (AF) ablation is crucial to minimize the risk of thromboembolic complications. There are broad ranges of approaches to anticoagulation management pre and post AF ablation procedures. The purpose of this study was to determine the anticoagulation strategies currently in use in patients peri- and post AF ablation in Canada. METHODS: A Web-based national survey of electrophysiologists performing AF ablation in Canada collected data regarding anticoagulation practice prior to ablation, periprocedural bridging, and duration of postablation anticoagulation. RESULTS: The survey was completed by 36 (97%) of the 37 electrophysiologists performing AF ablation across Canada. Prior to AF ablation, 58% of electrophysiologists started anticoagulation for patients with paroxysmal AF CHADS(2) scores of 0 to 1, 92% for paroxysmal AF CHADS(2) scores ≥ 2, 83% for persistent AF CHADS(2) scores of 0 to 1, and 97% for persistent AF CHADS(2) scores ≥ 2. For patients with CHADS(2) 0 to 1, warfarin was continued for at least 3 months by most physicians (89% for paroxysmal and 94% for persistent AF). For patients with CHADS(2) ≥ 2 and with no recurrence of AF at 1 year post ablation, 89% of physicians continued warfarin. CONCLUSIONS: Although guidelines recommend long-term anticoagulation in patients with CHADS(2) ≥ 2, 11% of physicians would discontinue warfarin in patients with no evidence of recurrent AF 1 year post successful ablation. Significant heterogeneity exists regarding periprocedural anticoagulation management in clinical practice. Clinical trial evidence is required to guide optimal periprocedural anticoagulation and therapeutic decisions regarding long-term anticoagulation after an apparently successful catheter ablation for AF.The Canadian journal of cardiology 07/2012; · 3.36 Impact Factor -
Article: Substrate and Trigger Ablation for Reduction of Atrial Fibrillation Trial-Part II (STAR AF II): design and rationale.
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ABSTRACT: The optimal ablation approach for patients with persistent atrial fibrillation (AF) remains unknown. In particular, it is unclear if pulmonary vein (PV) antral isolation (PVI) is sufficient as a lone strategy for persistent AF. Furthermore, if additional substrate ablation is to be added, the ideal approach to substrate ablation is yet to be determined. The aim of this study is to determine the optimal strategy of catheter ablation of persistent AF by comparing the efficacy of 3 strategies: PVI vs PVI plus complex fractionated electrogram (CFE) ablation (PVI + CFE) vs PVI plus linear ablation (PVI + Lines). The STAR AF II study (ClinicalTrials.gov NCT01203748) is a prospective, multicenter, randomized trial with a blinded assessment of outcomes. A total of 549 patients will be randomized in a 1:4:4 fashion to one of the investigation arms: PVI, PVI + CFE, and PVI + Lines, respectively. Patients undergoing a first-time ablation procedure for symptomatic, persistent AF that is refractory to at least 1 antiarrhythmic medication will be included. Persistent AF will be defined as a sustained episode lasting >7 days and <3 years. Patients with a left atrial parasternal size ≥60 mm will be excluded. The primary end point is freedom from documented AF >30 seconds at 18 months after 1 or 2 ablation procedures with or without antiarrhythmic medications. The STAR AF II study is a randomized trial designed to evaluate the optimal approach for catheter ablation of persistent AF.American heart journal 07/2012; 164(1):1-6.e6. · 4.65 Impact Factor -
Article: Incidence and Significance of Early Recurrences Associated with Different Ablation Strategies for AF: A STAR-AF Substudy.
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ABSTRACT: Early Recurrence in STAR-AF. Background: Early recurrences of atrial tachyarrhythmias (ERAT) are common after atrial fibrillation (AF) ablation, and predict late recurrences (LR). We sought to determine the impact of different ablation strategies on ERAT and LR. Methods and Results: The STAR-AF trial randomized 100 patients with paroxysmal or persistent AF to ablation of complex fractionated electrograms (CFAE) alone, pulmonary vein isolation (PVI) alone, or combined PVI + CFAE. Patients were followed for 12 months. ERAT was defined as any recurrence of AF, atrial tachycardia, or flutter (AT/AFL) >30 seconds during the first 3 months of follow-up. LR was defined as any recurrence of AF/AT/AFL >30 seconds 3-12 months post. Forty-nine patients experienced ERAT. The index ablation strategy was the only independent predictor of ERAT on multivariate analysis (HR 2.24 PVI vs PVI + CFAE; and HR 2.65 CFAE vs PVI + CFAE). Fifty-two patients experienced LR. The presence of ERAT (HR 3.23), the use of antiarrhythmic drug (AAD) in the first 3 months postablation (HR 2.85), and the index ablation strategy were independently associated with LR (HR 3.42 PVI vs PVI + CFAE; HR 4.72 CFAE vs PVI + CFAE). Thirty-five of 49 (71%) patients with ERAT and 17 (33%) of 51 patients without ERAT had LR (P < 0.0001). Among patients with ERAT, increased left atrium size (HR 1.08), the use of AAD in the first 3 months postablation (HR 2.86) and the index ablation strategy were independently associated with LR (HR 4.77 PVI vs PVI + CFAE; HR 4.45 CFAE vs PVI + CFAE). Conclusion: ERAT is common following AF ablation and is strongly associated with LR. Although CFAE ablation alone results in higher rates of early and LR, the addition of CFAE to PVI results in increased long-term success without an increase in ERAT. (J Cardiovasc Electrophysiol, Vol. pp. 1-7).Journal of Cardiovascular Electrophysiology 06/2012; · 3.06 Impact Factor -
Article: Point-by-point pulmonary vein antrum isolation guided by intracardiac echocardiography and 3D mapping and duty-cycled multipolar AF ablation: effect of multipolar ablation on procedure duration and fluoroscopy time.
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ABSTRACT: Pulmonary vein antrum isolation (PVAI) guided by intracardiac echocardiography and a roaming circular mapping catheter is an effective treatment modality for atrial fibrillation. Unfortunately, the complexity of this technique leads to long procedure times and high fluoroscopy exposure. Single-catheter multipolar ablation holds the promise to reduce these parameters. This study examined the effect of the conventional point-by-point PVAI with that of single-catheter multipolar ablation on the procedural characteristics and clinical outcomes of atrial fibrillation ablation. Referred patients underwent PVAI guided by a magnetic-based 3D mapping (CARTO 3(®) System; group 1) or duty-cycled multipolar AF ablation using the pulmonary vein ablation catheter (PVAC, group 2) between June 2010 and May 2011. Data were analyzed from 19 patients in group 1 and 31 patients in group 2. There was no significant difference in the length of the procedure between the two groups (135 ± 26 vs 125 ± 25 min, P = 0.20). Patients who underwent ablation using PVAC spent significantly less time in the procedure room pre- and post-procedure than those who underwent conventional PVAI (205 ± 38 vs 179 ± 30 min, P = 0.02) and had a significantly shorter fluoroscopy exposure (50 ± 16 vs 36 ± 14 min, P = 0.003) and radiofrequency energy delivery time (54 ± 26 vs 32 ± 33 min, P = 0.02). No differences in safety and efficacy were seen between the groups. Single-catheter multipolar AF ablation was associated with significantly lower fluoroscopy duration, radiofrequency energy delivery time, and the time the patient spent in the procedure room before and after ablation, although measured short-term clinical outcomes were similar.Journal of Interventional Cardiac Electrophysiology 03/2012; 34(3):303-10. · 1.17 Impact Factor -
Article: Nonphysiologic noise early after defibrillator implantation in Canada: incidence and implications: a report from the Canadian Heart Rhythm Society Device Committee.
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ABSTRACT: Following recent cases of nonphysiologic noise noted early after defibrillator implantation, the Canadian Heart Rhythm Society Device Committee decided to evaluate the implications of this problem. To determine the incidence and consequences of nonphysiologic noise early after defibrillator implantation. The Canadian Heart Rhythm Society Device Committee surveyed all Canadian defibrillator implanting centers regarding their implant volumes and number of cases where nonphysiologic noise had been noted early (< 24 hours) after implant over the preceding 2 years. For such cases, information regarding the manufacturer and occurrence of inappropriate shock or inhibition of pacing was reported. Responses were obtained from 20 of 23 surveyed implanting centers, with a total implant volume of 4960 defibrillators per year. The occurrence of nonphysiologic noise early after implantation was noted in 25 cases over the preceding 2 years (0.25%). Noise was detected in devices of all 3 of the leading volume device manufacturers. There were 2 cases of inappropriate shocks and 2 cases of symptomatic pacing inhibition. In 4 cases, removal of the lead from the header and retesting with the analyzer confirmed normal lead function. In all cases, the noise resolved within 24 hours. Nonphysiologic noise early after defibrillator implantation was noted in 0.25% of procedures and was not limited to one specific manufacturer. This noise may result in an inappropriate shock or inhibition of pacing in a pacemaker-dependent patient. This transient phenomenon, possibly related to fluid and/or air in the header, appears to always resolve without surgical intervention.Heart rhythm: the official journal of the Heart Rhythm Society 03/2012; 9(3):378-82. · 4.56 Impact Factor -
Article: Focused 2012 update of the Canadian Cardiovascular Society atrial fibrillation guidelines: recommendations for stroke prevention and rate/rhythm control.
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ABSTRACT: The Canadian Cardiovascular Society (CCS) published the complete set of 2010 Atrial Fibrillation (AF) Guidelines in the January, 2011 issue of the Canadian Journal of Cardiology. During its deliberations, the CCS Guidelines Committee engaged to a timely review of future evidence, with periodic composition of focused updates to address clinically important advances. In 2011, results were published from 3 pivotal AF trials: the Rivaroxaban Once Daily Oral Direct Factor Xa Inhibition Compared with Vitamin K Antagonist for Prevention of Stroke and Embolism Trial in Atrial Fibrillation (ROCKET-AF), the Apixaban for Reduction in Stroke and Other Thromboembolic Events in Atrial Fibrillation (ARISTOTLE) study, and the Permanent Atrial Fibrillation Outcome Study Using Dronedarone on Top of Standard Therapy (PALLAS), comparing dronedarone with placebo in patients with permanent AF and additional cardiovascular disease risk-factor burden. Each of these large randomized trials provided clear results with major implications for AF management. Other important evidence that has emerged since the 2010 Guidelines includes findings about prediction instruments for AF-associated stroke and bleeding risk, stroke risk in paroxysmal-AF patients, risk-benefit considerations related to oral anticoagulation in patients with chronic kidney disease, and risk/benefit considerations in the use of antiplatelet agents, alone and in combination with each other or with oral anticoagulants, in AF patients. The Guidelines Committee judged that this extensive and important new evidence required focused updating of the 2010 Guidelines with respect to stroke prevention and rate/rhythm control. This report presents the details of the new recommendations, along with the background and rationale.The Canadian journal of cardiology 03/2012; 28(2):125-36. · 3.36 Impact Factor -
Article: Clinical predictors of Fidelis lead failure: report from the Canadian Heart Rhythm Society Device Committee.
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ABSTRACT: Approximately 268,000 Fidelis leads were implanted worldwide until distribution was suspended because of a high rate of early failure. Careful analyses of predictors of increased lead failure hazard are required to help direct future lead design and also to inform decision making on lead replacement. We sought to perform a comprehensive analysis of all potential predictors in a multicenter study. A total of 3169 Sprint Fidelis leads were implanted in 11 centers with a total of 251 failures. Lead failure rates at 3, 4, and 5 years were 5.3%, 10.6%, and 16.8%, respectively. The rate of lead failure continues to accelerate (P<0.001). There were 4 independent predictors of failure: center, sex, access vein, and previous lead failure. Women had a higher hazard of failure (hazard ratio 1.51; 95% confidence interval, 1.14-2.04; P=0.005). Both axillary and subclavian access increased the hazard of failure (P=0.007); hazard ratio for axillary was 1.94, (95% confidence interval, 1.23-3.04) and for subclavian 1.63 (95% confidence interval, 1.08-2.46). Previous lead failure increased the hazard of a subsequent Fidelis failure with a hazard ratio of 3.12 (95% confidence interval, 1.80-5.41; P<0.001). The rate of Fidelis failure continues to increase over time, with failures approaching 17% at 5 years. Women, patients with leads inserted via the subclavian or axillary vein, and those with a previous lead fracture were at greatest risk of Fidelis failure. Our data suggest that Fidelis replacement should be strongly considered at the time of generator replacement.Circulation 02/2012; 125(10):1217-25. · 14.74 Impact Factor -
Article: Adenosine following pulmonary vein isolation to target dormant conduction elimination (ADVICE): methods and rationale.
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ABSTRACT: Pulmonary vein (PV) isolation (PVI) has emerged as an effective therapy for paroxysmal atrial fibrillation (AF). However, AF recurs in up to 50% of patients, generally because of recovery of PV conduction. Adenosine given during the initial procedure may reveal dormant PV conduction, thereby identifying the need for additional ablation, leading to improved outcomes. The Adenosine Following Pulmonary Vein Isolation to Target Dormant Conduction Elimination (ADVICE) study is a prospective multicentre randomized trial assessing the impact of adenosine-guided PVI in preventing AF recurrences. Patients undergoing a first PVI procedure for paroxysmal AF will be recruited. After standard PVI is completed, all patients will receive intravenous adenosine in an attempt to unmask dormant conduction. If dormant conduction is elicited, patients will be randomized to no further ablation (control group) or additional adenosine-guided ablation until dormant conduction is abolished. If no dormant conduction is revealed, randomly selected patients will be followed in a registry. The primary outcome is time to first documented symptomatic AF recurrence. Assuming that dormant conduction is present in 50% of patients post PVI and symptomatic AF recurs in 45% of controls, 244 patients with dormant conduction will be required to obtain > 90% power to detect a difference of 20%. Thus, a total of 488 patients will be enrolled and followed for 12 months. The ADVICE trial will assess whether a PVI strategy incorporating elimination of dormant conduction unmasked by intravenous adenosine will decrease the rate of recurrent symptomatic AF compared with standard PVI.The Canadian journal of cardiology 01/2012; 28(2):184-90. · 3.36 Impact Factor -
Article: The use of anticoagulation during the periprocedure period of atrial fibrillation ablation.
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ABSTRACT: Ablation is a treatment option for selected patients with atrial fibrillation that is being used more frequently, increasing the importance of awareness of both its risks and benefits. This review discusses the thromboembolic and bleeding risks during ablation, strategies to minimize these risks and use of long-term oral anticoagulation post ablation. Thromboembolic and bleeding risks imparted by atrial fibrillation ablation can be minimized by echocardiography, optimal intraprocedural anticoagulation, and use of irrigated catheters and access sheaths with constant heparinized saline flow. Additionally, a strategic approach to periprocedural anticoagulation that may include continuation of warfarin, bridging with low-molecular-weight heparin (LMWH), or use of aspirin alone is essential in the balance of thrombotic and hemorrhagic risks. Novel anticoagulants (direct thrombin inhibitors or anti-Xa inhibitors) may add further options. The use of atrial fibrillation ablation has increased over the past decade. Along with technique and technology advances that have improved the success of ablation, strides have been made in minimizing thromboembolic and bleeding risks and in the availability of a broader choice of anticoagulants. Research is ongoing to identify patients most suitable for ablation and to determine the long-term efficacy and safety of this treatment option.Current opinion in cardiology 01/2012; 27(1):55-61. · 2.66 Impact Factor -
Article: Early recurrence of atrial tachyarrhythmias following radiofrequency catheter ablation of atrial fibrillation.
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ABSTRACT: The use of blanking periods, the immediate period postablation during which transient tachyarrhythmia episodes are not considered recurrences, has been predicated on the assumption that not all early recurrences of atrial tachyarrhythmias (ERAT) will lead to later recurrences and, as such, does not necessarily represent treatment failure. While ERAT can be expected to occur in approximately 38% of patients within the first 3 months of atrial fibrillation (AF) ablation, only half of these patients will manifest later recurrences. Clinical features related to the patient's history of AF, the index ablation procedure, and particularities of the ERAT can help identify patients at higher risk of later recurrence in whom aggressive attempts to control rhythm, including early cardioversion and reintervention, may be justified.Pacing and Clinical Electrophysiology 11/2011; 35(1):106-16. · 1.35 Impact Factor -
Article: Relationship between complex fractionated electrograms (CFE) and dominant frequency (DF) sites and prospective assessment of adding DF-guided ablation to pulmonary vein isolation in persistent atrial fibrillation (AF).
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ABSTRACT: Sites of high DF are potential targets for AF ablation, but it is unknown if addition of DF ablation can improve procedural outcome. We sought to (1) examine the relationship between DF sites and complex fractionated electrograms (CFE) and (2) prospectively assess the long-term outcome of adding DF ablation to pulmonary vein antral isolation (PVAI) for persistent AF. Methods: First, 20 patients with persistent AF who underwent previous CFE-guided ablation and who had AF terminate during ablation were studied retrospectively (group I). Bipolar, 8-second electrograms were collected by a circular catheter (288 ± 86 points/map). The EnSite NavX system allows for automated display of both CFE and DF maps. Electrograms with cycle length <120 ms were considered CFE and were compared to DF sites > 8 Hz (direct inverse relationship). Sites of AF termination were related to CFE and DF sites. Based on these observations, 30 different patients (group II) with persistent AF prospectively underwent DF-guided ablation plus PVAI. They were followed every 3 months for 1 year (visit, Holter, ECG). These patients were compared to case-matched controls undergoing PVAI alone (group III). In group I, there was a significant, inverse correlation between DF and CFE values at each point (r =-0.24, P < 0.001). DF surface area was less than CFE area (27 ± 5 cm(2) vs 34 ± 4 cm(2) , P = 0.03). CFE sites overlapped 48 ± 27% with the DF surface area. Nonoverlapping CFE sites were contiguous to DF sites. AF termination occurred where DF and CFE overlapped, and at these sites, DF was always greater than the mean DF for the map. In group II, all DF sites above the mean value were prospectively ablated during AF. AF termination was noted in only 2/30 (7%) patients. After DF ablation, PVAI was performed and termination increased to 4/30 patients (14%). At 1 year, freedom from atrial arrhythmia > 30 seconds occurred in 57% of DF+PVAI compared to 60% in patients receiving PVAI alone (P = 0.18). DF and CFE regions overlap only about 50%. AF termination retrospectively occurred on overlapping CFE/DF sites where DF was above the mean. However, prospective ablation of DF sites plus PVAI resulted in low AF termination rates, and did not improve 1 year success over PVAI alone.Journal of Cardiovascular Electrophysiology 07/2011; 22(12):1309-16. · 3.06 Impact Factor -
Article: Left atrial 'sludge' during vagally mediated pause triggered by pulmonary vein antral ablation.
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ABSTRACT: We report a case of a patient with long-standing persistent atrial fibrillation (AF) who had rapid formation of spontaneous echo-contrast in the left atrium during pulmonary vein antrum isolation set off by a vagally mediated pause despite standard anticoagulation protocol. Spontaneous echo contrast resolved with ventricular pacing, representing visual evidence for dependence of some AF patients with poor atrial transport function on ventricular emptying with potential greater risk of thromboembolism related to a long ventricular pause.Europace 07/2011; 13(12):1797-8. · 1.98 Impact Factor -
Article: Clinical predictors of arrhythmia recurrences following pulmonary vein antrum isolation for atrial fibrillation: predicting arrhythmia recurrence post-PVAI.
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ABSTRACT: Pulmonary vein antrum isolation (PVAI) is an accepted treatment for atrial fibrillation (AF) refractory to medical therapy. The purpose of this study was to identify the patient, procedural, and follow-up factors associated with arrhythmia recurrences following PVAI. Clinical data were prospectively collected on all 385 consecutive patients who had 530 PVAI (age 58 ± 11 years, 63% paroxysmal AF-PAF, follow-up 2.8 ± 1.2 years) between February 2004 and March 2009. ECGs were recorded at each follow-up visit with Holter monitoring 1, 3, 6, and 12 months following PVAI and every 6 months thereafter. Recurrences < 3 months post-PVAI were defined as early, 3 months-1 year post-PVAI as late, and > 1 year post-PVAI as very late. Relationship between predictor variables and outcomes was modeled using Cox proportional hazards analysis. Late recurrences occurred in 42% with a lower rate among PAF versus non-PAF patients (39% vs 56%, P = 0.001). Of the 256 patients with ≥ 1-year follow-up, 121 (47%) had no arrhythmia off antiarrhythmic drugs (AADs) 1 year post-PVAI; 36 (30%) of these had a very late recurrence. In multivariate analysis, non-PAF, hypertension, and prior AAD failure predicted recurrence. When entered into the model, early recurrences remained the only predictor of late recurrences. Patients with non-PAF, hypertension, and prior failure of multiple AAD were more likely to experience arrhythmia recurrence post-PVAI. Early recurrences were the strongest predictor of late recurrences. Late and very late recurrences following PVAI were common and should be considered when planning long-term AF patient management.Journal of Cardiovascular Electrophysiology 06/2011; 22(11):1206-14. · 3.06 Impact Factor -
Article: Ablation of ventricular arrhythmias in arrhythmogenic right ventricular dysplasia/cardiomyopathy: arrhythmia-free survival after endo-epicardial substrate based mapping and ablation.
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ABSTRACT: In patients with arrhythmogenic right ventricular dysplasia/cardiomyopathy, freedom from ventricular arrhythmias (VAs) after endocardial ablation is limited. We compared the long-term freedom from recurrent VAs by using endocardial-alone ablation versus endo-epicardial substrate-based ablation. Forty-nine patients with arrhythmogenic right ventricular dysplasia/cardiomyopathy undergoing ablation of ventricular tachycardia (VT) were divided into 2 groups: endocardial-alone ablation (group 1, n = 23) and endo-epicardial ablation (group 2, n = 26). All patients had an implantable cardioverter-defibrillator (ICD). Conventional and 3D mappings were used to determine the mechanism of induced VTs and to identify area of "scar" or "abnormal" myocardium. All critical sites responsible for VTs and points with "abnormal" potential were targeted for ablation from endocardium (group 1) or from both endocardium and epicardium (group 2). The procedural end point was noninducibility of sustained, monomorphic VT with isoproterenol. The presence of frequent premature ventricular contractions at the end of ablation was recorded. Patients were followed up by ECG, Holter, and ICD interrogation. After a follow-up of at least 3 years, freedom from VAs or ICD therapy was 52.2% (12/23) in group 1 and 84.6% (22/26) in group 2 (P = 0.029), with 21.7% (5/23) and 69.2% (18/26) patients off antiarrhythmic drugs (P < 0.001), respectively. Compared with patients with no premature ventricular contractions after ablation, patients with frequent premature ventricular contractions after ablation were more likely to have VA recurrence/ICD therapy [3/33 (9%) versus 12/16 (75%); log-rank P<0.001]. An endo-epicardial-based ablation strategy achieves higher long-term freedom from recurrent VAs off antiarrhythmic therapy in patients with arrhythmogenic right ventricular dysplasia/cardiomyopathy when compared with endocardial-alone ablation. The presence of ≥ 10 premature ventricular contractions per minute after ablation is associated with more VA recurrence.Circulation Arrhythmia and Electrophysiology 06/2011; 4(4):478-85. · 6.46 Impact Factor -
Article: Is there an association between external cardioversions and long-term mortality and morbidity? Insights from the Atrial Fibrillation Follow-up Investigation of Rhythm Management study.
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ABSTRACT: Cardiac electric therapies effectively terminate tachyarrhythmias. Recent data suggest a possible increase in long-term mortality associated with implantable cardioverter-defibrillator shocks. Little is known about the association between external cardioversion episodes (ECVe) and long-term mortality. We sought to assess the safety of repeated ECVe with regard to cardiovascular mortality and morbidity. We analyzed the data of the 4060 patients from the AFFIRM (Atrial Fibrillation Follow-up Investigation of Rhythm Management) trial. In particular, associations of ECVe with all-cause mortality, cardiovascular mortality, and hospitalizations after ECVe were studied. Over an average follow-up of 3.5 years, 660 (16.3%) patients died, 331 (8.2%) from cardiovascular causes. A total of 207 (5.1%) and 1697 (41.8%) patients had low ejection fraction and nonparoxysmal atrial fibrillation, respectively; 2460 patients received no ECVe, whereas 1600 experienced ≥ 1 ECVe. Death occurred in 412 (16.7%), 196 (16.5%), 39 (13.5%), and 13 (10.4%) of patients with 0, 1, 2, and ≥ 3 ECVe, respectively. There was no significant association between ECVe and mortality within any of the 4 subgroups defined by ejection fraction and atrial fibrillation type, although myocardial infarction, coronary artery bypass graft, and digoxin were significantly associated with death (estimated hazard ratios, 1.65, 1.59, and 1.62, respectively; P < 0.0001). ECVe were associated with increased cardiac hospitalization reported at the next follow-up visit (39.3% versus 5.8%; estimated odds ratio, 1.39; P < 0.0001). In the AFFIRM study, there was no significant association between ECVe and long-term mortality, even though ECVe were associated with increased hospitalizations from cardiac causes. Digoxin, myocardial infarction, and coronary artery bypass graft were significantly associated with mortality.Circulation Arrhythmia and Electrophysiology 04/2011; 4(4):465-9. · 6.46 Impact Factor
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2007–2012
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Southlake Regional Health Centre
Bradford West Gwillimbury, Ontario, Canada
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2011
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St. David's North Austin Medical Center
Austin, TX, USA
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2010–2011
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University of Kentucky
Lexington, KY, USA -
Concordia University Texas
Austin, TX, USA
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2008–2011
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University of Toronto
- Division of Cardiology
Toronto, Ontario, Canada -
Kansas City University of Medicine and Biosciences
Kansas City, MO, USA -
Lakehead University Orillia Campus
Orillia, Ontario, Canada
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2009
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London Health Sciences Centre
London, Ontario, Canada
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2006–2009
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Cleveland Clinic
Cleveland, OH, USA -
Blood Centers of the Pacific
San Francisco, CA, USA
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