An active fixation quadripolar left ventricular lead for cardiac resynchronization therapy with reduced postoperative complication rates.

BACKGROUND: The rate of left ventricular (LV) lead displacement after cardiac resynchronization therapy (CRT) remains high despite improvements in lead technology. In 2017, a novel quadripolar lead with active fixation technology became available in the UK. METHODS: This was a retrospective, observational study analyzing device complications in 476 consecutive patients undergoing successful first-time implantation of a CRT device at a tertiary center from 2017 to 2020. RESULTS: Both active (n = 135) and passive fixation (n = 341) quadripolar leads had similar success rates for implantation (99.3% vs. 98.8%, p = 1.00), although the pacing threshold (0.89 [0.60-1.25] vs. 1.00 [0.70-1.60] V, p = .01) and lead impedance (632 [552-794] vs. 730 [636-862] Ohms, p < .0001) were significantly lower for the active fixation lead. Patients receiving an active fixation lead had a reduced incidence of lead displacement at 6 months (0.74% vs. 4.69%, p = .036). There was no significant difference in the rate of right atrial (RA) and right ventricular (RV) lead displacement between the two groups (RA: 1.48% vs. 1.17%, p = .68; RV: 2.22% vs. 1.76%, p = .72). Reprogramming the LV lead after displacement was unsuccessful in most cases (successful reprogramming: Active fix = 0/1, Passive fix = 1/16) therefore nearly all patients required a repeat procedure. As a result, the rate of intervention within 6 months for lead displacement was significantly lower when patients were implanted with the active fixation lead (0.74% vs. 4.40%, p = .049). CONCLUSION: The novel active fixation lead in our study has a lower incidence of lead displacement and re-intervention compared to conventional quadripolar leads for CRT.

Efficacy and safety of same-day discharge after atrial fibrillation ablation compared with post-procedural overnight stay: a systematic review and meta-analysis.

AIMS: Catheter ablation for atrial fibrillation (AF) has historically required inpatient admission post-procedure, but same-day discharge (SDD) has recently been reported. We aimed to assess the efficacy and safety of SDD compared with overnight stay (OS) post-ablation. METHODS AND RESULTS: We performed a systematic search of the PubMed database. Random-effects meta-analysis was performed to assess the efficacy (successful SDD) and safety (24 h complications, 30-day complications, 30-day re-admissions, and 30-day mortality) of a SDD AF ablation strategy. Fourteen non-randomized observational studies met criteria for inclusion, encompassing 26488 patients undergoing AF ablation, of whom 9766 were SDD. The mean age of participants was 61.9 years, and 67.9% were male. Around 61.7% underwent ablation for paroxysmal AF. The pooled success rate of SDD was 83.2% [95% confidence intervals (CIs): 61.5-97.0%, I2 100%]. The risk of bias was severe for all effect estimates due to confounding, as most cohorts were retrospectively identified without appropriately matched comparators. There was no significant difference in 30-day complications [odds ratio (OR): 0.95, 95% CI: 0.65-1.40, I2 53%] or 30-day re-admission (OR 0.96, 95% CI: 0.49-1.89, I2 82%) between groups. There were insufficient data for meta-analysis of 24 h complications and 30-day mortality. Where reported, no re-admissions occurred due to 24 h complications after SDD. Two deaths (0.04%) were reported in both SDD and OS groups. CONCLUSION: Same-day discharge after AF ablation appears to be an effective and safe strategy in selected patients. However, the available evidence is of low quality, and more robust prospective studies comparing SDD to OS are needed.

Endocardial left ventricular pacing for cardiac resynchronization: systematic review and meta-analysis.

Aims: Endocardial left ventricular (LV) pacing for Cardiac Resynchronization Therapy has been proposed as an alternative to conventional LV lead placement via the coronary sinus. In order to assess the relative benefits and risks of this technique, we have performed a meta-analysis of published reports. Methods and results: A systemic search was performed using online databases to identify studies of lead-based endocardial pacing. A random-effects meta-analysis was performed, to assess the rate of complications and clinical response (defined as ≥1 decrease in NYHA class). We selected 23 studies, including 384 patients. The trans-atrial septal technique was used in 20 studies, 1 used the trans-ventricular apical technique, and 2 used the trans-ventricular septal technique. Mean age was 66 years, male 66%, EF 26%, NYHA class 3.0. Procedural success rates were over 95% in all studies. Clinical response was reported by 16 studies for 262 patients, giving a response estimate of 82% (95% CI 71-89%). There was significant heterogeneity, and response in the only large study was 59%. Thromboembolic (TE) complications were reported by all studies, over 22 ±32 months follow up. The rate of stroke was 2.5 events per 100 patient years (95% CI 1.5-4.3), and TIA 2.6 (1.1-6.1). The mortality rate was 4.5 (1.5-13.6) per 100 patient years. Conclusion: LV endocardial pacing appears to be a viable technique when conventional lead placement is not possible. Response rates were heterogeneous but comparable with conventional CRT. There is likely to be a small increase over expected rates of stroke, although included patients were high risk.

Lone Atrial Fibrillation Is Associated With Impaired Left Ventricular Energetics That Persists Despite Successful Catheter Ablation.

BACKGROUND: Lone atrial fibrillation (AF) may reflect a subclinical cardiomyopathy that persists after sinus rhythm (SR) restoration, providing a substrate for AF recurrence. To test this hypothesis, we investigated the effect of restoring SR by catheter ablation on left ventricular (LV) function and energetics in patients with AF but no significant comorbidities. METHODS: Fifty-three patients with symptomatic paroxysmal or persistent AF and without significant valvular disease, uncontrolled hypertension, coronary artery disease, uncontrolled thyroid disease, systemic inflammatory disease, diabetes mellitus, or obstructive sleep apnea (ie, lone AF) undergoing ablation and 25 matched control subjects in SR were investigated. Magnetic resonance imaging quantified LV ejection fraction (LVEF), peak systolic circumferential strain (PSCS), and left atrial volumes and function, whereas phosphorus-31 magnetic resonance spectroscopy evaluated ventricular energetics (ratio of phosphocreatine to ATP). AF burden was determined before and after ablation by 7-day Holter monitoring; intermittent ECG event monitoring was also undertaken after ablation to investigate for asymptomatic AF recurrence. RESULTS: Before ablation, both LV function and energetics were significantly impaired in patients compared with control subjects (LVEF, 61% [interquartile range (IQR), 52%-65%] versus 71% [IQR, 69%-73%], P<0.001; PSCS, -15% [IQR, -11 to -18%] versus -18% [IQR, -17% to -19%], P=0.002; ratio of phosphocreatine to ATP, 1.81±0.35 versus 2.05±0.29, P=0.004). As expected, patients also had dilated and impaired left atria compared with control subjects (all P<0.001). Early after ablation (1-4 days), LVEF and PSCS improved in patients recovering SR from AF (LVEF, 7.0±10%, P=0.005; PSCS, -3.5±4.3%, P=0.001) but were unchanged in those in SR during both assessments (both P=NS). At 6 to 9 months after ablation, AF burden reduced significantly (from 54% [IQR, 1.5%-100%] to 0% [IQR 0%-0.1%]; P<0.001). However, LVEF and PSCS did not improve further (both P=NS) and remained impaired compared with control subjects (P<0.001 and P=0.003, respectively). Similarly, there was no significant improvement in atrial function from before ablation (P=NS), and this remained lower than in control subjects (P<0.001). The ratio of phosphocreatine to ATP was unaffected by heart rhythm during assessment and AF burden before ablation (both P=NS). It was unchanged after ablation (P=0.57), remaining lower than in control subjects regardless of both recovery of SR and freedom from recurrent AF (P=0.006 and P=0.002, respectively). CONCLUSIONS: Patients with lone AF have impaired myocardial energetics and subtle LV dysfunction, which do not normalize after ablation. These findings suggest that AF may be the consequence (rather than the cause) of an occult cardiomyopathy, which persists despite a significant reduction in AF burden after ablation.

Premature termination of radiofrequency delivery during pulmonary vein isolation due to oesophageal temperature alerts: impact on acute and chronic pulmonary vein reconnection.

AIMS: Oesophageal temperature monitoring is currently used during atrial fibrillation (AF) ablation to prevent atrio-oesophageal fistula. The aim of our study was to investigate if oesophageal temperature alerts, leading to early termination of radiofrequency (RF) energy and/or reduction in power during pulmonary vein isolation, can promote pulmonary vein reconnection (PVR). METHODS AND RESULTS: Patients undergone two consecutive AF ablation procedures with a three-dimensional electro-anatomical mapping system and oesophageal temperature monitoring were studied. Any lesions causing oesophageal temperature rises >39°C during the index procedure, leading to premature cessation of RF and/or reduction in power, were labelled on the left atrial geometry in a different colour from standard uninterrupted RF lesions. Acute (at the time of the index procedure) and chronic (at the time of there-do procedure) PVR and the site of subsequent re-isolation were compared with the lesion markers for temperature alerts from the index procedure. Fifty-four patients were included (36 male, mean age 68 ± 8, 59% persistent AF). Forty-six PVs (21% of the total) in 30 patients (56%) had been subject to at least one temperature alert during the index procedure. In 12 patients, 23 PVs had acute PVR requiring further ablation. At the re-do procedure, 103 PVs were found to be reconnected in 44 patients. No correlation was found between the occurrence of temperature alerts at the index procedure and acute or chronic PVR in the associated PV. CONCLUSION: Just over half of patients undergoing PV isolation will have an oesophageal temperature alert, however, precautionary oesophageal temperature monitoring does not compromise ablation efficacy.

Catheter ablation of atrial fibrillation in patients with heart failure: impact of maintaining sinus rhythm on heart failure status and long-term rates of stroke and death.

AIMS: Catheter ablation of atrial fibrillation (AF) in patients with heart failure (HF) can improve left ventricular (LV) function and HF symptoms. We aimed to investigate whether long-term maintenance of sinus rhythm impacts on hard outcomes such as stroke and death. METHODS AND RESULTS: An international multicentre registry was compiled from seven centres for consecutive patients undergoing catheter ablation of AF. Long-term freedom from AF was examined in patients with and without HF. The impact of maintaining sinus rhythm on rates of stroke and death was also examined. A total of 1273 patients were included: 171 with HF and 1102 without. Median follow-up was 3.1 years (IQR 2.0-4.3). The final procedure success rate was no different for paroxysmal AF (PAF) (78.7 vs. 85.7%, P = 0.186), but significantly different for persistent AF (57.3 vs. 75.8%, P < 0.001). Multivariate analysis showed that HF independently predicted recurrent arrhythmia [hazard ratio (HR) 1.7, 95% confidence interval (CI) 1.2-2.4, P = 0.002]. New York Heart Association class decreased from 2.3 ± 0.7 at baseline to 1.5 ± 0.8 at follow-up (P < 0.001). Left ventricular ejection fraction (LVEF) increased from 34.3 ± 9.0 to 45.8 ± 12.8% (P < 0.001). Recurrent AF was strongly predictive of stroke or death in HF patients (HR 8.33, 95% CI 1.86-37.7, P = 0.001). CONCLUSION: Long-term success rates for persistent (but not paroxysmal) AF ablation are significantly lower in HF patients. Left ventricular function and HF symptoms were improved following ablation. In HF patients, recurrent arrhythmia strongly predicted stroke and death during follow-up.

Inter- and intravein differences in cardiac output with cardiac resynchronization pacing using a multipolar LV pacing lead.

BACKGROUND: Quadripolar left ventricular pacing leads permit a variety of pacing configurations from different sites within a coronary vein. There may be advantages to selecting a specific pacing vector. This study examines whether the range of cardiac outputs obtained at cardiac resynchronization therapy (CRT) implantation is greater between different poles within a vein, or greater between two different veins. METHODS AND RESULTS: The cardiac index (CI, L/min/m(2) ) was measured during CRT implantation using a noninvasive cardiac output monitor (NICOM™, Cheetah Medical Inc., Newton Center, MA, USA) and a quadripolar left ventricle (LV) lead, in 22 patients with sinus rhythm. CI was recorded during right atrial-biventricular pacing at 70/min with fixed atrioventricular and ventriculo-ventricular delay, from each LV electrode in one vein, and then from an alternate vein. Phrenic nerve stimulation (PNS) occurred in nine of 15 posterior and three of 21 anterior veins (P = 0.005). At least one electrode in each vein had no PNS. The mean (standard deviation [SD]) difference between best and worst CI within any one vein was 13.1% (±9%). The mean (SD) difference between the best CI in one vein compared to the other was 9.8% (±8%; P = 0.043). In 16 of 22 patients, the range of CI was greater between poles within one vein, rather than between two veins (best of one vein compared to best from the other). In four of 22 patients, the range was greater between veins (P = 0.0003). CONCLUSION: A greater range of CI is found within a single vein than between two different veins. This finding has implications both for the approach to implant technique and postimplant programming and optimization.

Periprocedural stroke risk in patients undergoing catheter ablation for atrial fibrillation on uninterrupted warfarin.

BACKGROUND: Catheter ablation is an effective treatment for symptomatic individuals with atrial fibrillation (AF) but is associated with a risk of periprocedual stroke. Recent data suggest that this risk may be abolished if catheter ablation is performed with uninterrupted warfarin (UW). We sought to compare the incidence, severity and timing of periprocedural stroke between 2 periprocedural anticoagulation protocols: bridging low-molecular-weight heparin (LMWH) and UW. METHODS AND RESULTS: Periprocedural stroke (≤14 days) was assessed in 2,855 ablations performed in 1,813 patients. Thromboembolic stroke occurred in 11/1,653 (0.7%) procedures with bridging LMWH and in 5/1,202 (0.4%) procedures on UW (P = 0.5). Four of the 5 strokes (80%) on UW occurred despite a therapeutic INR and a mean activated clotting time of ≥300 seconds and 4/5 strokes (80%) occurred in patients with a CHADS2 score of 0. Eleven of 16 (69%) strokes overall occurred within 24 hours of the procedure. All 4 strokes resulting in major neurological deficit occurred in the LMWH group. Major bleeding complications occurred in 6.0% of patients in the bridging LMWH group compared to 4.0% in the UW group (P = 0.02). CONCLUSIONS: In contrast to existing data, periprocedural stroke still occurs despite therapeutic anticoagulation throughout the operative period. The optimal strategy to protect patients against thromboembolic stroke remains unclear.

Barriers to patients eligible for screening investigations and insertion of primary prevention implantable cardioverter defibrillators.

AIMS: Primary prevention (PP) implantable cardioverter defibrillator (ICD) implant rates in the UK are below national targets and barriers to this are not well known. This study was designed to identify the stages along the referral pathway from general to specialist care that eligible patients reach and what proportion eventually receive an ICD. METHODS AND RESULTS: A single institution database search was performed to identify all adults with severe left ventricular systolic dysfunction (left ventricular ejection fraction, LVEF≤35%), documented in the calendar year 2007. Medical records were assessed for age, heart failure aetiology, QRS duration, evidence of non-sustained ventricular tachycardia on Holter, electrophysiological study, and records of consultation with general physicians, cardiologists, and electrophysiologists (EPs) and reference to assessment of risk of sudden cardiac death and the role of ICD implantation. Three hundred twenty-six patients with LVEF ≤ 35% were identified from three electronic databases. Mean age was 72 ± 12 years. Seventy-two patients satisfied UK National Institute for Clinical Excellence guidelines for PP ICD implantation and 63 eligible for further screening. Of the 135 patients, 76 (56%) patients reviewed by a general cardiologist did not receive ICD implantation or referral for further assessment. When offered, ICD acceptance rate was high (35 vs. 3 patients who refused ICD). After seeing an EP, 8 of 47 (17%) patients were not offered ICD or further screening. The average age was 66.5 ± 6.2 years and no patient greater than 80 years had a PP ICD. CONCLUSIONS: Failure to refer from the general physician to cardiology and from the cardiologist to EP is the principle reason for low PP ICD implant rates among eligible patients in the UK.

A pacemaker magnet check alone is sufficient for the majority of patients postpacemaker implant.

BACKGROUND: Patients postpacemaker implant can undergo a full assessment by pacing system programmer (PSP) or a magnet check. The former takes longer, but provides more detailed information; a magnet-mode assessment is faster, but provides only capture data in an asynchronous pacing mode. A magnet-mode assessment alone may be sufficient in most cases, and current clinical practice varies considerably. METHODS: A retrospective single-center assessment of all pacemaker implants receiving PSP and magnet checks between September 2009 and April 2010. Patient records were reviewed. The results of PSP and magnet checks and any subsequent device-related management were noted. RESULTS: A total of 168 patients underwent pacemaker implantation, magnet-mode assessment, and then PSP interrogation during this period. Magnet-mode assessment revealed a problem in only one patient-failure of atrial capture, leading to subsequent atrial lead repositioning. None of the remaining 167 patients have a serious problem at PSP interrogation; six had minor issues at PSP check, none of which required repeat surgical intervention. CONCLUSIONS: The magnet-mode test only provides information on lead capture in an asynchronous pacing mode, which is the most essential data postoperatively. Our study has suggested that a magnet-mode assessment without PSP interrogation may be sufficient in the immediate postimplant assessment of these patients. Routine postimplant PSP interrogation is time consuming, labor intensive, and adds only minimal additional benefit to the safe management of these patients above and beyond a magnet check, coupled with informed assessment of the associated electrocardiogram/rhythm strip, clinical examination, and chest x-ray.

Feasibility of mitral isthmus and left atrial roof linear lesions using an 8 mm tip cryoablation catheter.

BACKGROUND: Left atrial linear lesions are part of the ablation strategy for persistent atrial fibrillation. Radiofrequency (RF) energy is the standard energy modality. Pulmonary vein (PV) balloon cryoablation has similar success rates to RF energy but is unsuitable for linear lesions. This study assessed the feasibility and safety of left atrial linear lesions using an 8 mm tip cryoablation catheter. METHODS AND RESULTS: Consecutive patients undergoing left atrial ablation procedures for paroxysmal or persistent atrial fibrillation were studied. An 8 mm tip focal cryoablation catheter was used to create mitral isthmus and left atrial roof linear lesions and compared to a matched cohort undergoing RF ablation. A total of 21 patients (54 ± 11 years, 14 male), 15 undergoing de novo procedures using a dual console technique (simultaneous focal catheter and cryoballoon PV ablation) and 6 redo procedures (single console and focal catheter) were studied. Mitral isthmus ablation was successful in 19/21 (91%) with a mean total ablation time of 32.5 ± 2.9 minutes. Roof line ablation was successful in 18/19 with a mean ablation time of 15.6 ± 6.0 minutes. Success rates were similar but ablation times were longer than those in the matched RF group. Epicardial ablation in the coronary sinus was required less often with cryoablation (11/21 vs 17/21, P < 0.05). There were no complications. CONCLUSION: Left atrial linear lesions with an 8 mm tip cryoablation catheter are feasible and safe with a high acute success rate. The need for coronary sinus ablation is reduced. A dual console technique is possible. Long-term durability of linear lesions remains to be determined.

Absolute risk reduction in total mortality with implantable cardioverter defibrillators: analysis of primary and secondary prevention trial data to aid risk/benefit analysis.

AIMS: Absolute risk reduction (ARR) and number needed to treat (NNT) are considered by many to be the most appropriate figures to use for the informed consent process, yet the results of published implantable cardioverter defibrillators (ICD) trials are frequently presented as relative risk reduction or odds ratio. The period over which risk reduction is calculated also varies between trials, making comparison difficult. METHODS AND RESULTS: Published ICD trials used to formulate national and international guidelines were examined for 1, 2, and 3 year total mortality in ICD and medically treated patients. The number of patients enrolled and at risk at these time points were also sought. Where the raw data were not included in the original text, estimates were taken from published Kaplan-Meier graphs. Eight primary prevention (PP) trials, three secondary prevention (SP) trials, and one SP meta-analyses were included. For PP, ARR at 3-year follow-up ranged from 0 (no benefit) to 24.6% (NNT = 4). For SP, ARR at 3-year follow up ranged from 3.7% (NNT = 27) to 11.3% (NNT = 9). Absolute risk reduction increased with follow-up in PP trials, whereas there was considerable variation in SP trials. Overall, very few trial patients received 3-year follow-up, giving wide confidence intervals (CIs). CONCLUSION: Absolute risk reduction from ICD trials varies significantly depending upon trial entry criteria, subgroup characteristics, and duration of follow-up. The relatively small number of patients followed for 2 or more years leads to wide CIs. Despite these limitations, the standardized ARR and NNT data presented may give a more individualized estimate of risk/benefit that could potentially aid an informed consent process.

Mitral isthmus ablation is feasible, efficacious, and safe using a remote robotic catheter system.

BACKGROUND: There are limited data on the use of a remote robotic catheter system (RCS) for mitral isthmus (MI) ablation. METHODS: This single-center, prospective, matched control study included 45 patients who underwent atrial fibrillation ablation using a remote RCS compared to 45 patients who underwent conventional ablation. All patients had circumferential pulmonary vein isolation (PVI), roof, and MI ablation. RESULTS: There were no significant differences in baseline clinical characteristics. There were no significant differences in MI block (RCS: 44/45 [98%] vs CONTROL: 43/45 [96%], P = 1.0), roof block (RCS: 45/45 [100%] vs CONTROL: 44/45 [98%], P = 1.0), and PVI (RCS: 45/45 [100%] vs CONTROL: 45/45 [100%], P = 1.0). Ablation and procedural times were similar in both arms. Using RCS, mean total MI ablation and procedure times were 13 ± 6 minutes and 23 ± 15 minutes, respectively. Coronary sinus (CS) ablation was significantly less in the RCS arm (48% vs 72%, P = 0.03). It was possible to "drive" the ablation catheter into the distal CS using the RCS in 19/22 (86%) patients. There was a significant trend of reduction in mean MI ablation (P = 0.008) and procedural times (P = 0.004) over the course of the study period. There was a significant reduction in fluoroscopy time in the RNS arm (33 ± 17 minutes vs 49 ± 20 minutes, P = 0.0004). CONCLUSION: It is feasible and safe to use a remote RCS for MI ablation, including "driving into the CS." MI block was achieved in 98% with a significant reduction in the need for CS ablation (48%). There is a short learning curve.

Mitral isthmus ablation using steerable sheath and high ablation power: a single center experience.

BACKGROUND: Mitral isthmus ablation is challenging. The use of steerable sheath and high ablation power may improve success rate. METHODS: This single-center, prospective study enrolled 200 patients who underwent ablation for atrial fibrillation (AF), including mitral isthmus ablation. Mitral isthmus ablation was performed using an irrigated ablation catheter via a steerable sheath (endocardium: maximum power: 40/50 W limited to annular end, maximum temperature: 48 °C; coronary sinus [CS]: maximum power: 25/30 W, maximum temperature: 48 °C). Endpoint was bidirectional mitral isthmus block. RESULTS: Mitral isthmus block was acutely achieved in 182/200 patients (91%). Sixty-nine percent of patients required CS ablation. Mean total ablation time was 13 ± 6 minutes. There was 1 case of acute circumflex artery occlusion. Mean left atrium (LA) diameter was significantly bigger in patients with unsuccessful mitral isthmus ablation (49 ± 4 mm vs. 43 ± 6 mm; P = 0.0007). In redo procedures, the incidence of reconduction at the mitral isthmus, roof and cavotricuspid isthmus was 44%, 37%, and 29%, respectively. Overall incidence of perimitral flutter was 9%. Prior complex fractionated atrial electrogram ablation was a predictor for microreentrant atrial tachycardia (AT) whereas gaps in linear lesions predicted macroreentrant flutters. After a mean follow-up of 20 ± 9 months, 73% of patients remained free from AF or AT. CONCLUSION: We reported on a series of mitral isthmus ablation using steerable sheath and high ablation power (50 W). Larger LA diameter was a predictor of failure to achieve mitral isthmus block. The mitral isthmus had a moderately high incidence of re-conduction but was only associated with a relatively low incidence of perimitral flutter.

Questionnaire survey of cardiologists' knowledge, attitudes, and guideline application of implantable cardioverter defibrillator therapy.

INTRODUCTION: There are little data on cardiologists' knowledge and application of current implantable cardioverter defibrillator (ICD) guidelines, attitudes to risk, and how these may influence ICD prescription. METHODS: A questionnaire survey was sent to UK cardiologists to test their knowledge and application of ICD guidelines and their estimate of the clinical benefits gained in different clinical scenarios. They were questioned on the minimum absolute risk reduction (ARR) required to justify an ICD implant and factors that influenced their decision making. RESULTS: Sixty responses from 23 implanters and 37 nonimplanters were obtained. Eighty-three percent implanters and 43% nonimplanters were fully aware of UK ICD National Institute of Clinical Excellence guidelines. Only 7% responders had a screening program to identify primary prevention (PP) candidates. Although the mean estimate of ARR in PP scenarios was similar to trial data, the range of estimates was very wide. The benefit in secondary prevention (SP) scenarios was overestimated by both implanters and nonimplanters. Three-year ARR believed to justify PP and SP ICDs were heavily influenced by patients' age but in patients <80 years, age was compatible with trial results. Implanters and nonimplanters correctly applied guidelines in SP scenarios with younger patients but often withheld an ICD in elderly patients. Correct application did not correlate with full awareness of guidelines. CONCLUSION: Lack of knowledge of guidelines (particularly in nonimplanters), failure of nonimplanters to offer ICDs to appropriate PP patients, age bias, and a lack of screening programs appear to be the greatest barriers to uptake of ICDs in the United Kingdom, rather than financial concerns.

High incidence of acute sub-clinical circumflex artery 'injury' following mitral isthmus ablation.

AIMS: Mitral isthmus (MI) ablation is technically challenging, requiring long endocardial ablation times and frequently coronary sinus (CS) ablation. The circumflex artery lies in the epicardium in close proximity to the CS and the mitral annulus and may potentially be injured during radiofrequency ablation. METHODS AND RESULTS: Fifty-four patients underwent catheter ablation procedures that included MI ablation for treatment of atrial fibrillation. Irrigated ablation catheters were used with the following settings: endocardial surface (max power: 40/50 W at the annular end; max temperature: 48°C); CS (max power: 25/30 W; max temperature: 48°C). Coronary angiography was performed pre- and post-ablation and analysed by two cardiologists with quantitative coronary angiography. Mitral isthmus block was achieved in 89% of patients (60% required CS ablation). Fifteen patients (28%) had angiographic changes following ablation: eight had mid-circumflex narrowing only, one had circumflex and obtuse marginal (OM) artery narrowing, one had OM narrowing only, and five had distal circumflex occlusion/narrowing. Five patients had significant narrowing (50-84%), which resolved with intracoronary glycerine trinitrate. Fourteen (93%) of the patients with circumflex 'injury' had CS ablation and a longer mean CS ablation time (5.0 ± 3.0 vs. 2.6 ± 3.3 min, P = 0.03). Patients with distal circumflex occlusion had significantly smaller vessel diameter (1.0 ± 0.1 vs. 2.1 ± 0.2 mm, P = 0.03). A shorter distance between the circumflex and the CS was also associated with circumflex 'injury' (3.2 ± 1.9 vs. 5.6 ± 3.2 mm, P = 0.04). There were no electrocardiographic or echocardiographic abnormalities and no angina symptoms during follow-up. CONCLUSION: Acute sub-clinical circumflex 'injury' following MI ablation is not uncommon. Ablation within the CS, proximity of the circumflex and the CS, and a small distal circumflex were risk factors for 'injury'.

Clinical and economic impact of extracardiac lesions on coronary CT angiography.

OBJECTIVE: When reporting coronary CT angiography (CCTA), extracardiac structures are routinely assessed, usually on a wide field-of-view (FOV) reconstruction. We performed a retrospective observational cross-sectional study to investigate the impact of incidental extracardiac abnormalities on resource utilisation and treatment, and cost-effectiveness. METHODS: All patients undergoing CCTA at a single institution between January 2012 and March 2020 were identified. The indication for CCTA was chest pain or dyspnoea in >90%. Patients with ≥1 significant extracardiac findings were selected. Clinical follow-up, investigations and treatment were documented, and costs were calculated. RESULTS: 4340 patients underwent CCTA; 717 extracardiac abnormalities were identified in 687 individuals (15.8%; age 62±12 years; male 336, 49%). The abnormality was already known in 162 (23.6%). Lung nodules and cysts were the most common abnormalities (296, 43.1%). Clinical and/or imaging follow-up was pursued in 292 patients (42.5%). Treatment was required by 14 patients (0.3% of the entire population), including lung resection for adenocarcinoma in six (0.1%). All but two abnormalities (both adenocarcinomas) were identifiable on the limited cardiac FOV. The cost of reporting (£20) and follow-up (£33) of extracardiac abnormalities was £53 per patient. The cost per discounted quality-adjusted life year was £23 930, increasing to £46 674 for reporting the wide FOV rather than the cardiac FOV alone. CONCLUSIONS: Extracardiac abnormalities are common on CCTA, but identification and follow-up are costly. The few requiring treatment are usually identifiable without review of the wide FOV. The way in which CCTAs are scrutinised for extracardiac abnormalities in a resource-limited healthcare system should be questioned.

Atrial nitroso-redox balance and refractoriness following on-pump cardiac surgery: a randomized trial of atorvastatin.

AIMS: Systemic inflammation and increased activity of atrial NOX2-containing NADPH oxidases have been associated with the new onset of atrial fibrillation (AF) after cardiac surgery. In addition to lowering LDL-cholesterol, statins exert rapid anti-inflammatory and antioxidant effects, the clinical significance of which remains controversial. METHODS AND RESULTS: We first assessed the impact of cardiac surgery and cardiopulmonary bypass (CPB) on atrial nitroso-redox balance by measuring NO synthase (NOS) and GTP cyclohydrolase-1 (GCH-1) activity, biopterin content, and superoxide production in paired samples of the right atrial appendage obtained before (PRE) and after CPB and reperfusion (POST) in 116 patients. The effect of perioperative treatment with atorvastatin (80 mg once daily) on these parameters, blood biomarkers, and the post-operative atrial effective refractory period (AERP) was then evaluated in a randomized, double-blind, placebo-controlled study in 80 patients undergoing cardiac surgery on CPB. CPB and reperfusion led to a significant increase in atrial superoxide production (74% CI 71-76%, n = 46 paired samples, P < 0.0001) and a reduction in atrial tetrahydrobiopterin (BH4) (34% CI 33-35%, n = 36 paired samples, P < 0.01), and in GCH-1 (56% CI 55-58%, n = 26 paired samples, P < 0.001) and NOS activity (58% CI 52-67%, n = 20 paired samples, P < 0.001). Perioperative atorvastatin treatment prevented the effect of CPB and reperfusion on all parameters but had no significant effect on the postoperative right AERP, troponin release, or NT-proBNP after cardiac surgery. CONCLUSION: Perioperative statin therapy prevents post-reperfusion atrial nitroso-redox imbalance in patients undergoing on-pump cardiac surgery but has no significant impact on postoperative atrial refractoriness, perioperative myocardial injury, or markers of postoperative LV function. CLINICAL TRIAL REGISTRATION: https://clinicaltrials.gov/ct2/show/NCT01780740.

Larger coronary sinus diameter predicts the need for epicardial delivery during mitral isthmus ablation.

AIMS: Mitral isthmus ablation is technically challenging, often requiring both endocardial and epicardial coronary sinus (CS) ablation. Blood flow in the CS and circumflex artery may act as a 'heat sink' and reduce the efficacy of radiofrequency ablation. This study investigates how the CS and circumflex artery diameters affect mitral isthmus ablation. METHODS AND RESULTS: Thirty-five patients underwent ablation for atrial fibrillation. Irrigated-tip catheters were used during mitral isthmus ablation with the following settings: endocardial surface (maximum power: 40-50 W at the annular end of line; maximum temperature: 48°C); CS (maximum power: 25-30 W; maximum temperature: 48°C). The absence of block after 10 min of endocardial ablation led to CS ablation for up to 5 min. If there was still no block, further ablation was at the discretion of the physician. Coronary angiography and CS venography were performed and analysed with quantitative coronary angiography. Mitral isthmus block was achieved in 31 patients (89%). Twenty-three patients (74%) required CS ablation to achieve block. These patients were found to have significantly larger CS diameters (6.5 ± 1.2 vs. 5.4 ± 0.5 mm, P< 0.02). Coronary sinus diameter >59 mm predicted the need for CS ablation (specificity: 100%; sensitivity: 78%). Coronary sinus diameter correlated significantly with total mitral isthmus ablation time (r = 0.52, P < 0.003) and CS ablation time (r = 0.59, P < 0.0005), whereas circumflex diameter did not. CONCLUSION: Larger-diameter CS is associated with a need for CS ablation during mitral isthmus ablation. Coronary sinus but not circumflex diameter was significantly correlated with total and CS ablation time, supporting the hypothesis that the CS but not the circumflex artery acts as a heat sink.

Local activation times at the high posterior wall of the left atrium during left atrial appendage pacing predict roof line block with high specificity and sensitivity.

AIMS: Ensuring complete block after left atrial (LA) linear lesions is important as partial block may be pro-arrhythmic. Techniques to confirm roof line block may be time consuming and challenging and have not been well described. This study investigates whether local activation times (LAT) during left atrial appendage (LAA) pacing help in the assessment of roof line block. METHODS AND RESULTS: Forty-five patients underwent ablation for atrial fibrillation (AF) including circumferential pulmonary vein isolation, roof, and mitral isthmus lines. Local activation times were measured at pre-defined points on the posterior wall and high anterior wall during LAA pacing at the following stages: (i) baseline; (ii) incomplete roof line; (iii) roof block; and (iv) roof and mitral isthmus block. Time from pacing at high posterior wall to LAA was also recorded at each stage. Receiver operator curve analyses were performed on different parameters to assess if they could confirm roof line block. There was a stepwise increase in mean high posterior wall LAT: 83 ± 16 ms (baseline); 105 ± 20 ms (incomplete roof block); 133 ± 26 ms (roof block), and 152 ± 35 ms (roof and MI block; one way analysis of variance, P< 0.0001). Increased LA diameter, amiodarone use, and adjunctive complex fractionated atrial electrogram ablation were associated with longer LATs. For patients with persistent AF, LAA to high posterior wall times of >133 ms, high posterior wall to LAA times of >125 ms and double potential >77 ms predict roof line block with high specificity and sensitivity especially if there was also mitral isthmus block. CONCLUSION: Parameters derived from the measurement of LAT of the high posterior and anterior LA wall help guide the assessment of roof line block.