Louise Segan - Academia.edu (original) (raw)

Papers by Louise Segan

JACC: Clinical Electrophysiology, 2022

OBJECTIVES This study sought to describe the utility of automated conduction velocity mapping (AC... more OBJECTIVES This study sought to describe the utility of automated conduction velocity mapping (ACVM) in ventricular tachycardia (VT) ablation. BACKGROUND Identification of areas of slowed conduction velocity (CV) is critical to our understanding of VT circuits and their underlying substrate. Recently, an ACVM called Coherent Mapping (Biosense Webster Inc) has been developed for atrial mapping. However, its utility in VT mapping has not been described. METHODS Patients with paired high-density VT activation and substrate maps were included. ACVM was applied to paired VT activation and substrate maps to assess regional CV and activation patterns. A combination of ACVM, traditional local activation time maps, electrogram analysis, and off-line calculated CV using triangulation were used to characterize zones of slowed conduction during VT and in substrate mapping. RESULTS Fifteen patients were included in the study. In all cases, ACVM identified slow CV within the putative VT isthmus, which colocalized to the VT isthmus identified with entrainment. The dimensions of the VT isthmus with local activation time mapping were 37.8 ± 13.7 mm long and 8.7 ± 4.2 mm wide. In comparison, ACVM produced an isthmus that was shorter (length: 25.1 ± 10.6 mm; mean difference: 12.8; 95% CI: 7.5-18.0; P < 0.01) and wider (width: 18.8 ± 8.1 mm; mean difference: 10.1; 95% CI: 6.1-14.2; P < 0.01). In VT, the CV using triangulation at the entrance (8.0 ± 3.6 cm/s) and midisthmus (8.1 ± 4.3 cm/s) was not significantly different (P = 0.92) but was significantly faster at the exit (16.2 ± 9.7 cm/s; P < 0.01). In the paired substrate analysis, traditional local activation time isochronal mapping identified 6.3 ± 2.0 deceleration zones. In contrast, ACVM identified a median of 0 deceleration zones (IQR: 0-1; P < 0.01). CONCLUSIONS ACVM is a novel complementary tool that can be used to accurately resolve complex VT circuits and identify slow conduction zones in VT but has limited accuracy in identifying slowed conduction during substrate-based mapping.

JACC: Clinical Electrophysiology, 2022

Background: Although catheter ablation (CA) is an effective treatment for patients with AF and LV... more Background: Although catheter ablation (CA) is an effective treatment for patients with AF and LVSD, the efficacy of an initial cryo-ablation strategy is unknown. This study evaluated long term outcomes of patients with an initial cryo-ablation strategy for AF and LV systolic dysfunction (LVSD). Methods: Outcomes of patients undergoing index cryoablation for AF from January 2008 until March 2018, with documented pre-ablation LVEF?45% were evaluated for long term freedom from AF and change in ventricular function from baseline. Results: 76 patients met inclusion criteria. Patients were predominantly male (80%), aged 63 ?11yrs, with an average CHADS2 VASc score of 2.66 ? 1.40, baseline LVEF 34 ? 8.7% (ischaemic in 37%) and NYHA class 2.37 ? 0.72. Repeat procedures were performed in 13%. The single procedure success was 70% at 1 year (81% for paroxysmal AF, 65% for persistent AF, 29% for long-standing persistent AF) and at 28 ? 13 months follow up was 43% (50%, 41% and 21% respectively), increasing to 59% allowing for subsequent redo procedure with RF ablation (64%, 57%, and 50% respectively). At follow up, LVEF significantly improved to 46 ? 16% (p<0.001), and NYHA reduced to 1.51 ? 0.66 (p<0.001). Conclusion: An initial strategy of cryoablation in patients with AF and LVSD is an effective approach in the treatment of patients with concurrent AF and LVSD. Larger, randomised prospective studies are required to confirm these findings.

Heart, Lung and Circulation, 2020

Background Recent reports describe a high rate of premature lead failure in the St Jude/Abbott Te... more Background Recent reports describe a high rate of premature lead failure in the St Jude/Abbott Tendril TM 2088 (St. Jude Medical Inc., St. Paul, MN, USA) pacing lead principally manifested by electrical noise. This finding awaits confirmation. Methods We performed a retrospective analysis of 2088 Tendril TM leads among 362 patients implanted from 2010 to 2018. Eligible leads were those with device interrogations beyond one month from lead implantation. Review of serial device interrogations was conducted for each lead, particularly focussing on electrical noise as a marker of premature lead dysfunction. Results Four hundred and eight (408) leads among 337 patients were included in this study, with an average patient age of 81611 years at the time of lead implantation. Mean follow-up was 2.561.8 years. There were eight leads with electrical noise indicating premature lead failure. This reflects an overall 1.7% rate of lead dysfunction; the failure rate was 6.2% at 4 years. The majority of cases were detected during routine checks without adverse clinical consequences. Four (4) cases required device reprogramming to avoid interference or inhibition due to noise. Conclusion The rate of Tendril TM 2088 premature lead failure appears to be similar to recent local and international studies. This study reports a significantly higher rate of lead dysfunction at 4 years (6.2%) than the published Abbott product performance reports.

European Heart Journal - Case Reports, 2019

Background Poly ADP-ribose polymerase (PARP) inhibitors target pathogenic BRCA mutations in chemo... more Background Poly ADP-ribose polymerase (PARP) inhibitors target pathogenic BRCA mutations in chemotherapy-resistant malignancies. PARP inhibitors cause modest dose-dependent QT prolongation in the setting of a normal baseline QT interval. Case summary We describe a case of PARP inhibitor-induced torsades de pointes (TdP) in an 86-year-old gentleman prescribed rucaparib due to chemotherapy-resistant, metastatic prostate cancer with pre-existing long QT, with an apparent dose-dependent increase in QT interval. The patient presented with syncope and recurrent TdP requiring direct cardioversion reversion (200 J biphasic) and an isoprenaline infusion (2 μg/min). There were no other QT prolonging agents and no electrolyte or metabolic disturbance to account for this arrhythmia. Improvement in QT interval was observed within 72 h of rucaparib cessation. Discussion PARP inhibitors cause a modest, dose-dependent increase in QT interval in patients with a normal baseline. The safety of PARP in...

JACC: Clinical Electrophysiology, 2019

OBJECTIVES The goal of this study was to characterize, in detail, focal atrial tachycardia (AT) a... more OBJECTIVES The goal of this study was to characterize, in detail, focal atrial tachycardia (AT) arising from the crista terminalis to investigate associations with other atrial arrhythmia and to define long-term ablation outcomes. BACKGROUND The crista terminalis is known to be the most common site of origin for focal AT, but it is not well characterized. METHODS This study retrospectively identified a total of 548 ablation procedures for AT performed at a single center over a 16-year period, of which 171 were arising from the crista terminalis. RESULTS Compared with patients with other AT sites of origin, crista terminalis AT patients were older (57.3 vs. 47.3 years), more commonly female (72.9% vs. 59.1%), were more commonly associated with coexistent atrioventricular nodal re-entry tachycardia (17.1% vs. 9.7%), and were more likely to be inducible with programmed stimulation (81.5% vs. 58.9%). There was preferential conduction in the superior-inferior axis along the crista terminalis. Acute ablation success rate was high (92.2%) and improved significantly when three-dimensional mapping was used (98.5%). Recurrence in the first 12 months after a successful ablation was 9.7%. Only 2 patients developed atrial fibrillation over the long-term follow-up of >7 years. CONCLUSIONS This large series characterized the clinical and electrophysiological features and immediate and longterm ablation outcomes for AT originating from the crista terminalis. Features of the tachycardia suggest that age-related localized remodeling of the crista terminalis causes a superficial endocardial zone of conduction slowing leading to reentry. Ablation outcomes were good, with long-term freedom from atrial arrhythmia.

JACC: Clinical Electrophysiology, 2022

OBJECTIVES This study sought to describe the utility of automated conduction velocity mapping (AC... more OBJECTIVES This study sought to describe the utility of automated conduction velocity mapping (ACVM) in ventricular tachycardia (VT) ablation. BACKGROUND Identification of areas of slowed conduction velocity (CV) is critical to our understanding of VT circuits and their underlying substrate. Recently, an ACVM called Coherent Mapping (Biosense Webster Inc) has been developed for atrial mapping. However, its utility in VT mapping has not been described. METHODS Patients with paired high-density VT activation and substrate maps were included. ACVM was applied to paired VT activation and substrate maps to assess regional CV and activation patterns. A combination of ACVM, traditional local activation time maps, electrogram analysis, and off-line calculated CV using triangulation were used to characterize zones of slowed conduction during VT and in substrate mapping. RESULTS Fifteen patients were included in the study. In all cases, ACVM identified slow CV within the putative VT isthmus, which colocalized to the VT isthmus identified with entrainment. The dimensions of the VT isthmus with local activation time mapping were 37.8 ± 13.7 mm long and 8.7 ± 4.2 mm wide. In comparison, ACVM produced an isthmus that was shorter (length: 25.1 ± 10.6 mm; mean difference: 12.8; 95% CI: 7.5-18.0; P < 0.01) and wider (width: 18.8 ± 8.1 mm; mean difference: 10.1; 95% CI: 6.1-14.2; P < 0.01). In VT, the CV using triangulation at the entrance (8.0 ± 3.6 cm/s) and midisthmus (8.1 ± 4.3 cm/s) was not significantly different (P = 0.92) but was significantly faster at the exit (16.2 ± 9.7 cm/s; P < 0.01). In the paired substrate analysis, traditional local activation time isochronal mapping identified 6.3 ± 2.0 deceleration zones. In contrast, ACVM identified a median of 0 deceleration zones (IQR: 0-1; P < 0.01). CONCLUSIONS ACVM is a novel complementary tool that can be used to accurately resolve complex VT circuits and identify slow conduction zones in VT but has limited accuracy in identifying slowed conduction during substrate-based mapping.

JACC: Clinical Electrophysiology, 2022

Background: Although catheter ablation (CA) is an effective treatment for patients with AF and LV... more Background: Although catheter ablation (CA) is an effective treatment for patients with AF and LVSD, the efficacy of an initial cryo-ablation strategy is unknown. This study evaluated long term outcomes of patients with an initial cryo-ablation strategy for AF and LV systolic dysfunction (LVSD). Methods: Outcomes of patients undergoing index cryoablation for AF from January 2008 until March 2018, with documented pre-ablation LVEF?45% were evaluated for long term freedom from AF and change in ventricular function from baseline. Results: 76 patients met inclusion criteria. Patients were predominantly male (80%), aged 63 ?11yrs, with an average CHADS2 VASc score of 2.66 ? 1.40, baseline LVEF 34 ? 8.7% (ischaemic in 37%) and NYHA class 2.37 ? 0.72. Repeat procedures were performed in 13%. The single procedure success was 70% at 1 year (81% for paroxysmal AF, 65% for persistent AF, 29% for long-standing persistent AF) and at 28 ? 13 months follow up was 43% (50%, 41% and 21% respectively), increasing to 59% allowing for subsequent redo procedure with RF ablation (64%, 57%, and 50% respectively). At follow up, LVEF significantly improved to 46 ? 16% (p<0.001), and NYHA reduced to 1.51 ? 0.66 (p<0.001). Conclusion: An initial strategy of cryoablation in patients with AF and LVSD is an effective approach in the treatment of patients with concurrent AF and LVSD. Larger, randomised prospective studies are required to confirm these findings.

Heart, Lung and Circulation, 2020

Background Recent reports describe a high rate of premature lead failure in the St Jude/Abbott Te... more Background Recent reports describe a high rate of premature lead failure in the St Jude/Abbott Tendril TM 2088 (St. Jude Medical Inc., St. Paul, MN, USA) pacing lead principally manifested by electrical noise. This finding awaits confirmation. Methods We performed a retrospective analysis of 2088 Tendril TM leads among 362 patients implanted from 2010 to 2018. Eligible leads were those with device interrogations beyond one month from lead implantation. Review of serial device interrogations was conducted for each lead, particularly focussing on electrical noise as a marker of premature lead dysfunction. Results Four hundred and eight (408) leads among 337 patients were included in this study, with an average patient age of 81611 years at the time of lead implantation. Mean follow-up was 2.561.8 years. There were eight leads with electrical noise indicating premature lead failure. This reflects an overall 1.7% rate of lead dysfunction; the failure rate was 6.2% at 4 years. The majority of cases were detected during routine checks without adverse clinical consequences. Four (4) cases required device reprogramming to avoid interference or inhibition due to noise. Conclusion The rate of Tendril TM 2088 premature lead failure appears to be similar to recent local and international studies. This study reports a significantly higher rate of lead dysfunction at 4 years (6.2%) than the published Abbott product performance reports.

European Heart Journal - Case Reports, 2019

Background Poly ADP-ribose polymerase (PARP) inhibitors target pathogenic BRCA mutations in chemo... more Background Poly ADP-ribose polymerase (PARP) inhibitors target pathogenic BRCA mutations in chemotherapy-resistant malignancies. PARP inhibitors cause modest dose-dependent QT prolongation in the setting of a normal baseline QT interval. Case summary We describe a case of PARP inhibitor-induced torsades de pointes (TdP) in an 86-year-old gentleman prescribed rucaparib due to chemotherapy-resistant, metastatic prostate cancer with pre-existing long QT, with an apparent dose-dependent increase in QT interval. The patient presented with syncope and recurrent TdP requiring direct cardioversion reversion (200 J biphasic) and an isoprenaline infusion (2 μg/min). There were no other QT prolonging agents and no electrolyte or metabolic disturbance to account for this arrhythmia. Improvement in QT interval was observed within 72 h of rucaparib cessation. Discussion PARP inhibitors cause a modest, dose-dependent increase in QT interval in patients with a normal baseline. The safety of PARP in...

JACC: Clinical Electrophysiology, 2019

OBJECTIVES The goal of this study was to characterize, in detail, focal atrial tachycardia (AT) a... more OBJECTIVES The goal of this study was to characterize, in detail, focal atrial tachycardia (AT) arising from the crista terminalis to investigate associations with other atrial arrhythmia and to define long-term ablation outcomes. BACKGROUND The crista terminalis is known to be the most common site of origin for focal AT, but it is not well characterized. METHODS This study retrospectively identified a total of 548 ablation procedures for AT performed at a single center over a 16-year period, of which 171 were arising from the crista terminalis. RESULTS Compared with patients with other AT sites of origin, crista terminalis AT patients were older (57.3 vs. 47.3 years), more commonly female (72.9% vs. 59.1%), were more commonly associated with coexistent atrioventricular nodal re-entry tachycardia (17.1% vs. 9.7%), and were more likely to be inducible with programmed stimulation (81.5% vs. 58.9%). There was preferential conduction in the superior-inferior axis along the crista terminalis. Acute ablation success rate was high (92.2%) and improved significantly when three-dimensional mapping was used (98.5%). Recurrence in the first 12 months after a successful ablation was 9.7%. Only 2 patients developed atrial fibrillation over the long-term follow-up of >7 years. CONCLUSIONS This large series characterized the clinical and electrophysiological features and immediate and longterm ablation outcomes for AT originating from the crista terminalis. Features of the tachycardia suggest that age-related localized remodeling of the crista terminalis causes a superficial endocardial zone of conduction slowing leading to reentry. Ablation outcomes were good, with long-term freedom from atrial arrhythmia.