Long-term outcomes of index cryoballoon ablation or point-by-point radiofrequency ablation in patients with atrial fibrillation and systolic heart failure.

Catheter ablation is an established effective approach for the treatment of atrial fibrillation (AF) in patients with heart failure, however, the role of cryoablation in this setting is unclear. Procedural success and left ventricular systolic dysfunction (LVEF) improvement in patients with LVEF ≤ 45% undergoing index catheter ablation with cryoablation were evaluated. Freedom from AF recurrence was seen in 43% rising to 59% following repeat procedure. There were significant improvements in LVEF and functional status at long-term follow-up. Results were comparable to a contemporaneous cohort of heart failure patients undergoing index ablation with radiofrequency ablation. Cryoablation is an effective first-line AF ablation approach in the setting of heart failure.

Left atrial scarring and conduction velocity dynamics: Rate dependent conduction slowing predicts sites of localized reentrant atrial tachycardias.

BACKGROUND: Low voltage zones (LVZs) are associated with conduction velocity (CV) slowing. Rate-dependent CV slowing may play a role in reentry mechanisms. METHODS: Patients undergoing catheter ablation for AT were enrolled. Aim was to assess the relationship between rate-dependent CV slowing and sites of localized reentrant atrial tachycardias (AT). On a bipolar voltage map regions were defined as non-LVZs [≥0.5 mV], LVZs [0.2-0.5 mV] and very-LVZs [<0.2 mV]. Unipolar electrograms were recorded with a 64-pole basket catheter during uninterrupted atrial pacing at four pacing intervals (PIs) during sinus rhythm. CVs were measured between pole pairs along the wavefront path. Sites of rate-dependent CV slowing were defined as exhibiting a reduction in CV between PI = 600 ms and 250 ms of ≥20% more than the mean CV reduction seen between these PIs for that voltage zone. Rate-dependent CV slowing sites were correlated to sites of localized reentrant ATs as confirmed with conventional mapping, entrainment and response to ablation. RESULTS: Eighteen patients were included (63 ±â€¯10 years). Mean CV at 600 ms was 1.53 ±â€¯0.19 m/s in non-LVZs, 1.14 ±â€¯0.15 m/s in LVZs, and 0.73 ±â€¯0.13 m/s in very-LVZs respectively (p < 0.001). Rate-dependent CV slowing sites were predominantly in LVZs [0.2-0.5 mV] (74.4 ±â€¯10.3%; p < 0.001). Localized reentrant ATs were mapped to these sites in 81.8% of cases (sensitivity 81.8%, 95% CI 48.2-97.9% and specificity 83.9%, 95% CI 81.8-86.0%). Macro-reentrant or focal ATs were not mapped to sites of rate-dependent CV slowing. CONCLUSIONS: Rate-dependent CV slowing sites are predominantly confined to LVZs [0.2-0.5 mV] and the resultant CV heterogeneity may promote reentry mechanisms. These may represent a novel adjunctive target for AT ablation.

Impact of attributed audit on procedural performance in cardiac electrophysiology catheter laboratory.

PURPOSE: Audit has played a key role in monitoring and improving clinical practice. However, audit often fails to drive change as summative institutional data alone may be insufficient to do so. We hypothesised that the practice of attributed audit, wherein each individual's procedural performance is presented will have a greater impact on clinical practice. This hypothesis was tested in an observational study evaluating improvement in fluoroscopy times for AF ablation. METHODS: Retrospective analyses of fluoroscopy times in AF ablations at the Barts Heart Centre (BHC) from 2012-2017. Fluoroscopy times were compared pre- and post- the introduction of attributed audit in 2012 at St Bartholomew's Hospital (SBH). In order to test the hypothesis, this concept was introduced to a second group of experienced operators from the Heart Hospital (HH) as part of a merger of the two institutions in 2015 and change in fluoroscopy times recorded. RESULTS: A significant drop in fluoroscopy times (33.3 ± 9.14 to 8.95 ± 2.50, p < 0.0001) from 2012-2014 was noted after the introduction of attributed audit. At the time of merger, a significant difference in fluoroscopy times between operators from the two centres was seen in 2015. Each operator's procedural performance was shared openly at the audit meeting. Subsequent audits showed a steady decrease in fluoroscopy times for each operator with the fluoroscopy time (min, mean±SD) decreasing from 13.29 ± 7.3 in 2015 to 8.84 ± 4.8 (p < 0.0001) in 2017 across the entire group. CONCLUSIONS: Systematic improvement in fluoroscopy times for AF ablation procedures was noted byevaluating individual operators' performance. Attributing data to physicians in attributed audit can promptsignificant improvement and hence should be adopted in clinical practice.

Moderate sedation in cardiac electrophysiology laboratory: a retrospective safety analysis.

OBJECTIVE: Cardiac electrophysiology (EP) procedures can be performed under moderate sedation without the direct involvement of an anaesthetist. However, concerns have been raised over the safety of this approach. This study examines the use of a standardised nurse-led physician-directed sedation protocol for EP procedures to determine the safety of moderate sedation administered by non-anaesthesia personnel who have been trained in sedation techniques. METHODS AND RESULTS: Consecutive EP procedures done under moderate sedation over 12 years at our institution were evaluated. Serious adverse events were defined as (i) procedural death related to sedation; (ii) intubation and ventilation; and (iii) hypotension requiring inotropic support. Reversal of sedation constituted a minor adverse event. Up to 7117 procedures were included. These comprised ablations (55%), devices (43%) and other procedures (2%). A majority of patients were men with a mean age of 61±10 years. 99.98% of procedures were completed successfully without sedation-related serious adverse events. Two patients (0.02%) required anaesthetic support for intubation. Sedation was reversed in 1.2% of procedures with less than 1% requiring reversal because of persistent drop in oxygen saturation, hypoventilation or markedly reduced level of consciousness. There was no significant difference in the patient characteristics, mean doses of sedative agents and procedure types in the group requiring reversal of sedation when compared with the whole cohort. CONCLUSIONS: Our study demonstrates that nurse-led, physician-directed moderate sedation is safe. Anaesthesia services are not required routinely for invasive cardiac EP procedures and should be available on a need basis.

Epicardial catheter ablation for ventricular tachycardia on uninterrupted warfarin: A safe approach for those with a strong indication for peri-procedural anticoagulation?

BACKGROUND: Current guidelines for epicardial catheter ablation for ventricular tachycardia (VT) advocate that epicardial access is avoided in anticoagulated patients and should be performed prior to heparinisation. Recent studies have shown that epicardial access may be safe in heparinised patients. However, no data exist for patients on oral anticoagulants. We investigated the safety of obtaining epicardial access on uninterrupted warfarin. METHODS: A prospective registry of patients undergoing epicardial VT ablation over two years was analysed. Consecutive patients in whom epicardial access was attempted were included. All patients were heparinised prior to epicardial access with a target activated clotting time (ACT) of 300-350s. Patients who had procedures performed on uninterrupted warfarin (in addition to heparin) were compared to those not taking an oral anticoagulant. RESULTS: 46 patients were included of which 13 were taking warfarin. There was no significant difference in clinical and procedural characteristics (except INR and AF) between the two groups. Epicardial access was achieved in all patients. There were no deaths and no patients required surgery. A higher proportion of patients in the warfarin group had a drop in haemoglobin of >2g/dL compared to the no-warfarin group (38.5% versus 27.3%, p=0.74) and delayed pericardial drain removal (7.8% versus 3.03%, p=0.47). There was no difference in overall procedural complication rate. No patients required warfarin reversal or blood transfusion. CONCLUSION: Epicardial access can be achieved safely and effectively in patients' anticoagulated with warfarin and heparinised with therapeutic ACT. This may be an attractive option for patients with a high stroke risk.

Telomere shortening and telomerase activity in ischaemic cardiomyopathy patients - Potential markers of ventricular arrhythmia.

BACKGROUND: Implantable cardioverter defibrillators (ICDs) reduce mortality in patients with ischaemic cardiomyopathy at high risk of ventricular arrhythmias (VA). However, the current indication for ICD prescription needs improvement. Telomere and telomerase in leucocytes have been shown to associate with biological ageing and pathogenesis of cardiovascular diseases. We hypothesised that leucocyte telomere length, load-of-short telomeres and/or telomerase activity are associated with VA occurrence in ischaemic cardiomyopathy patients. METHODS AND RESULTS: 90 ischaemic cardiomyopathy patients with primary prevention ICDs were recruited. 35 had received appropriate therapy from the ICD for potentially-fatal VA while the remaining 55 patients had not. No significant differences in baseline demographic data relevant to telomere biology were seen between the two groups. There was no significant difference in the age and sex adjusted mean telomere length analysed by qPCR between the groups (p=0.88). In contrast, the load-of-short telomeres assessed by Universal-STELA method and telomerase activity by TRAP assay were both higher in patients who had appropriate ICD therapy and were significantly associated with incidence of ICD therapy (p=0.02, p=0.02). ROC analyses demonstrated that the sensitivity and specificity of these telomere dynamics in predicting potentially-fatal VA was higher than the current gold-standard - left ventricular ejection fraction (AUC 0.82 versus 0.47). CONCLUSION: The load-of-short telomeres and telomerase activity had a significant association with ICD therapy (for VA) in ischaemic cardiomyopathy patients. These biomarkers should be tested in prospective studies to assess their clinical utility in predicting VA after myocardial infarction and guiding primary prevention ICD prescription.

Importance of primary percutaneous coronary intervention for reducing mortality in ST-elevation myocardial infarction complicated by out of hospital cardiac arrest.

BACKGROUND: Current recommendations are for primary percutaneous coronary intervention (pPCI) in ST-elevation myocardial infarction (STEMI) complicated by out of hospital cardiac arrest (OHCA). However, information about longer-term outcomes is sparse, particularly among high-risk patients who do not regain consciousness promptly after resuscitation. METHODS AND RESULTS: Of 1836 consecutive patients admitted with STEMI for pPCI between April 2008-October 2011, 132 (7.2%) who had suffered OHCA with recovery of spontaneous circulation (ROSC) form the study population. 101 patients survived to hospital discharge (76.5%) with only one further death in the first year. Prognosis was worse for the 62 patients who were unconscious on arrival and required admission to the intensive therapy unit (ITU), only 54% of whom survived. Every additional minute in the time to ROSC increased the hazard of death by 1.7% while alertness upon ROSC and successful reperfusion in response to pPCI reduced the hazard of death by 90% and 65% respectively. Full neurological recovery was recorded in 85.1% of those who survived to be discharged but in only 30.6% of the 34 survivors who were admitted unconscious and received ITU treatment. Every additional minute in the time to ROSC increased the odds of neurological deficit by 7.0%. CONCLUSIONS: In patients with STEMI who are conscious after OHCA, high rates of survival can be achieved with pPCI, depending in part on the time it takes for ROSC. Prognosis is less good in the subgroup brought to hospital unconscious but even in this high risk group neurologically intact survival can be achieved in about one-third of cases, suggesting the benefit of immediate pPCI in STEMI patients successfully resuscitated after OHCA.

Long-term efficacy of catheter ablation for atrial fibrillation: impact of additional targeting of fractionated electrograms.

OBJECTIVES: To investigate long-term efficacy of catheter ablation for atrial fibrillation (AF) and the impact of ablating complex or fractionated electrograms (CFEs) in addition to pulmonary vein isolation and linear lesions in persistent AF (PeAF). METHODS: Consecutive cases from 2002-2007 were analysed. All the patients underwent a wide-area circumferential ablation with confirmation of electrical isolation. For PeAF, linear lesions were added, with additional targeting of CFE from 2005. Data were collected in a prospective database. Attempts were made to contact all patients for follow-up. RESULTS: 285 patients underwent 530 procedures. The mean (SD) age was 57 (11) years, 75% were male, 20% had structural heart disease and 53% had paroxysmal AF (PAF). The mean number of procedures was 1.9 per patient (1.7 for PAF and 2.0 for PeAF). Procedural complications included stroke or transient ischemic attack in 0.6% and pericardial effusion requiring drainage in 1.7%. During 2.7 years (0.2 to 7.4 years) of follow-up from the last procedure, there were seven deaths (unrelated to their ablation or AF) and three strokes or transient ischemic attack (0.3% per year). Freedom from AF/atrial tachyarrhythmia was 86% for PAF and 68% for PeAF. Late recurrence was 3 per 100 years of follow-up after >3 years. The Kaplan-Meier analysis showed that CFE ablation improved the outcome for PeAF after the first cluster of procedures (p=0.049), with a trend towards improved final outcome (p=0.130). CONCLUSIONS: Long-term freedom from AF is achievable in most patients with PAF and PeAF with low rates of late recurrence. Additional targeting of CFE improves outcome for PeAF. Late adverse events including stroke are few.

Catheter ablation of permanent atrial fibrillation: medium term results.

OBJECTIVE: To investigate the feasibility of catheter ablation as a treatment for symptomatic patients with longstanding permanent atrial fibrillation (AF). METHODS: Radiofrequency ablation was applied to encircle all pulmonary veins (PVs) and create lines from the left inferior PV to the mitral valve, along the roof of the left atrium between the PVs, and along the tricuspid valve-inferior vena cava isthmus. A seven day Holter was recorded at discharge and at follow up to assess arrhythmia burden. If patients developed a symptomatic, sustained atrial arrhythmia a repeat ablation procedure was advised. RESULTS: 42 patients underwent the procedure that took a mean of five hours with 50 minutes of fluoroscopy. After a median follow up of 8.4 months, 31 of 41 surviving patients (76%) were in sinus rhythm. Of these, 29 patients were no longer taking any antiarrhythmic drugs but 22 (52%) required more than one procedure. During follow up 49% experienced a sustained atrial tachycardia. Twenty six repeat procedures were performed. Maintenance of sinus rhythm after the first, second, or third procedure was 36% (15 of 42), 58% (11 of 19), and 71% (5 of 7), respectively. From a total of 68 procedures there were two serious complications (2.9%): a stroke from which a full recovery was made, and a PV stenosis. CONCLUSION: Catheter ablation can be used to cure longstanding permanent AF; however, there is a significant complication rate. Whether this is offset by a mortality benefit associated with sinus rhythm is unknown. Many patients will need more than one procedure to achieve success.

Ventricular arrhythmia, Cheyne-Stokes respiration, and death: observations from patients with defibrillators.

OBJECTIVE: To determine whether ventricular arrhythmia related to nocturnal hypoxaemia during Cheyne-Stokes respiration (CSR) explains the observation that CSR is an independent marker of death in heart failure. DESIGN: Prospective, observational study. PATIENTS: 101 patients at high risk of clinical serious ventricular arrhythmia fitted with an implantable cardioverter-defibrillator (ICD). MEASUREMENTS: Patients were studied at baseline for CSR during sleep. Arrhythmia requiring device discharge was used as a surrogate marker for possible sudden cardiac death. RESULTS: 101 patients (42 with CSR) were followed up for a total of 620 months. Twenty six patients experienced 432 ICD discharge episodes. Twenty four (6%), 210 (49%), 125 (29%), and 73 (17%) episodes occurred across the time quartiles 0000-0559, 0600-1159, 1200-1759, and 1800-2359, respectively. Kaplan-Meier analysis showed a relative risk of 1 (95% confidence interval 0.5 to 2.2, p = 1) for device discharge in the CSR group. The average (SED) numbers of nocturnal ICD discharges per patient per month of follow up were 0.01 (0.01) and 0.04 (0.02) for patients with and without CSR, respectively (p = 0.6). CONCLUSION: These findings refute the proposition that CSR is related to heart failure death through nocturnal serious ventricular arrhythmia.