Atrial fibrillation cryoablation is an effective day case treatment: the UK PolarX vs. Arctic Front Advance experience.

AIMS: Pulmonary vein isolation (PVI) is the cornerstone of catheter ablation for atrial fibrillation (AF). There are limited data on the PolarX Cryoballoon. The study aimed to establish the safety, efficacy, and feasibility of same day discharge for Cryoballoon PVI. METHODS AND RESULTS: Multi-centre study across 12 centres. Procedural metrics, safety profile, and procedural efficacy of the PolarX Cryoballoon with the Arctic Front Advance (AFA) Cryoballoon were compared in a cohort large enough to provide definitive comparative data. A total of 1688 patients underwent PVI with cryoablation (50% PolarX and 50% AFA). Successful PVI was achieved with 1677 (99.3%) patients with 97.2% (n = 1641) performed as day case procedures with a complication rate of <1%. Safety, procedural metrics, and efficacy of the PolarX Cryoballoon were comparable with the AFA cohort. The PolarX Cryoballoon demonstrated a nadir temperature of -54.6 ± 7.6°C, temperature at 30 s of -38.6 ± 7.2°C, time to -40°C of 34.1 ± 13.7 s, and time to isolation of 49.8 ± 33.2 s. Independent predictors for achieving PVI included time to reach -40°C [odds ratio (OR) 1.34; P < 0.001] and nadir temperature (OR 1.24; P < 0.001) with an optimal cut-off of ≤34 s [area under the curve (AUC) 0.73; P < 0.001] and nadir temperature of ≤-54.0°C (AUC 0.71; P < 0.001), respectively. CONCLUSIONS: This large-scale UK multi-centre study has shown that Cryoballoon PVI is a safe, effective day case procedure. PVI using the PolarX Cryoballoon was similarly safe and effective as the AFA Cryoballoon. The cryoablation metrics achieved with the PolarX Cryoballoon were different to that reported with the AFA Cryoballoon. Modified cryoablation targets are required when utilizing the PolarX Cryoballoon.

A retrospective analysis of frailty status on atrial fibrillation catheter ablation outcomes.

INTRODUCTION: Catheter ablation for atrial fibrillation (AF) reduces symptoms and improves the quality of life compared with medical treatment. It is unclear if frailty impacts on the outcome of catheter ablation in patients with symptomatic AF. We sought to evaluate the association between frailty as measured by the validated NHS electronic Frailty Index (eFI) and outcomes post-AF ablation. METHODS: Two hundred forty eight patients who had undergone AF ablation with a mean age of 72.9 ± 5.16 were included in the study retrospectively. The primary endpoint for success was defined as freedom from atrial arrhythmia lasting >30 s beyond the 3-month blanking periods. Frailty was based on the eFI, and the cohort split into four groups: fit (no frailty), mild, moderate and severe frailty. RESULTS: Frailty was categorized as fit (118/248; 47.6%), mild (66/248; 26.6%), moderate (54/248; 21.8%), and severe (10/248; 4.0%). Freedom from arrhythmia occurred in 167 of 248 (67.3%) patients after a mean follow-up of 25.8 +/- 17.3 months. Fit patients had significantly greater freedom from arrhythmia (92/118; 78%) compared to mild frailty (40/66; 60.6%, p-value = .020), moderate frailty (31/54; 57.4%, p-value = .006), or severe frailty (4/10; 40.0%, p-value < .001). There was also a significant difference in arrhythmia occurrence between patients with mild frailty and severe frailty (p-value = .044). CONCLUSION: Frailty is associated with poorer outcomes in patients undergoing AF ablation. The eFI may be used in the prognostic evaluation of AF ablation outcomes. Further studies are essential to confirm the findings of this study.

A randomized sham-controlled study of pulmonary vein isolation in symptomatic atrial fibrillation (The SHAM-PVI study): Study design and rationale.

INTRODUCTION: Pulmonary vein (PV) isolation has been shown to reduce atrial fibrillation (AF) burden and symptoms in patients. However, to date previous studies have been unblinded raising the possibility of a placebo effect to account for differences in outcomes. HYPOTHESIS & METHODS: The objective of this study is to compare PV isolation to a sham procedure in patients with symptomatic AF. The SHAM-PVI study is a double blind randomized controlled clinical trial. 140 patients with symptomatic paroxysmal or persistent AF will be randomized to either PV isolation (with cryoballoon ablation) or a sham procedure (with phrenic nerve pacing). All patients will receive an implantable loop recorder. The primary outcome is total AF burden at 6 months postrandomisation (excluding the 3 month blanking period). Key secondary outcomes include (1) time to symptomatic and asymptomatic atrial tachyarrhythmia (2) total atrial tachyarrhythmia episodes and (3) patient reported outcome measures. RESULTS: Enrollment was initiated in January 2020. Through April 2023 119 patients have been recruited. Results are expected to be disseminated in 2024. CONCLUSION: This study compares PV isolation using cryoablation to a sham procedure. The study will estimate the effect of PV isolation on AF burden.

A randomized comparison of retrograde left-sided versus anterograde right-sided ablation of the atrioventricular junction.

BACKGROUND: Catheter ablation of the atrioventricular node (AVN) is an effective treatment for patients with symptomatic atrial fibrillation. This study compares the success rate, procedure time, radiation time, and complication rates of retrograde left-sided (LSA) and anterograde right-sided (RSA) AVN ablation in a randomised controlled trial. METHODS: Thirty-one patients undergoing AVN ablation were randomized to either LSA (15 patients) or RSA (16 patients). Crossover occurred after six unsuccessful radiofrequency (RF) applications. RESULTS: The LSA cohort had a mean age of 77.00 ± 5.17 and the RSA cohort was 79.44 ± 6.08 (p = .0240). There were five crossovers from LSA to RSA and there was one crossover from RSA to LSA. There was no significant difference in ablation time between LSA and RSA (210.40 ± 179.77 vs. 192.19 ± 130.29 seconds, p = .748). There was no significant difference in procedure time, fluoroscopy time, radiation dose, or number of RF applications between the two groups. There was 1 (6.67%) serious adverse event in the LSA group and 1 (6.25%) in the RSA group due to femoral hematomas requiring blood transfusion or intervention. There was no significant difference in patient-reported discomfort between LSA and RSA (16.43 ± 20.67 vs. 17.87 ± 28.08, p = .877). The study was stopped before full recruitment due to futility. CONCLUSIONS: Retrograde LSA of the AVN does not reduce RF applications, procedure time, or radiation exposure compared with conventional RSA and cannot be recommended as a first-line clinical approach.

Immediate implantable loop recorder implantation for detecting atrial fibrillation in cryptogenic stroke.

INTRODUCTION: Atrial fibrillation (AF) is suspected as the main cause of stroke in the majority of patients presenting with cryptogenic stroke (CS). Implantable loop recorders (ILR's) are indicated for detecting AF in these patients. The short term (<1 month) and long-term AF detection rates in patients inserted with an ILR immediately after CS is reported. Secondly, we compare the safety of nurse led vs physician led ILR implantation in these patients. METHODS: This is a retrospective review of all patients who underwent inpatient ILR implantation (Medtronic Linq) between May 2020 and May 2022 at East Sussex Healthcare NHS trust. All patients were remotely monitored via the FOCUSONTM monitoring and triage service. RESULTS: A total of 186 subjects were included in the study and were followed up for a mean period of 363.0 +/- 222.6 days. The mean time between stroke and ILR was 7.0 +/- 5.5 days. The mean time between referral and ILR was 1.0 +/- 2.0 days. AF was detected in 25 (13.4%) patients. During the first 30 days of monitoring, AF was detected in 9 (4.8%) patients. The number of ILR implants performed by the specialist nurse was 107 (57.5%). There was no significant difference in the major complication rate (requiring device removal) between nurse and physician led implant (1 (0.95%) vs 0 (0%), p value = 0.389). CONCLUSION: Inpatient ILR for cryptogenic stroke is feasible. The rate of AF detection in the first month post CS is 4.8% however, more AF was detected up to one year post implant, suggesting rationale for proceeding directly to ILR implant in these patients before discharge to not delay treatment. A nurse led service is also viable with no significant difference in the major complication rate compared to physician led implants.

Ablation versus anti-arrhythmic therapy for reducing all hospital episodes from recurrent atrial fibrillation: a prospective, randomized, multi-centre, open label trial.

AIMS: There is rising healthcare utilization related to the increasing incidence and prevalence of atrial fibrillation (AF) worldwide. Simplifying therapy and reducing hospital episodes would be a valuable development. The efficacy of a streamlined AF ablation approach was compared to drug therapy and a conventional catheter ablation technique for symptom control in paroxysmal AF. METHODS AND RESULTS: We recruited 321 patients with symptomatic paroxysmal AF to a prospective randomized, multi-centre, open label trial at 13 UK hospitals. Patients were randomized 1:1:1 to cryo-balloon ablation without electrical mapping with patients discharged same day [Ablation Versus Anti-arrhythmic Therapy for Reducing All Hospital Episodes from Recurrent (AVATAR) protocol]; optimization of drug therapy; or cryo-balloon ablation with confirmation of pulmonary vein isolation and overnight hospitalization. The primary endpoint was time to any hospital episode related to treatment for atrial arrhythmia. Secondary endpoints included complications of treatment and quality-of-life measures. The hazard ratio (HR) for a primary endpoint event occurring when comparing AVATAR protocol arm to drug therapy was 0.156 (95% CI, 0.097-0.250; P < 0.0001 by Cox regression). Twenty-three patients (21%) recorded an endpoint event in the AVATAR arm compared to 76 patients (74%) within the drug therapy arm. Comparing AVATAR and conventional ablation arms resulted in a non-significant HR of 1.173 (95% CI, 0.639-2.154; P = 0.61 by Cox regression) with 23 patients (21%) and 19 patients (18%), respectively, recording primary endpoint events (P = 0.61 by log-rank test). CONCLUSION: The AVATAR protocol was superior to drug therapy for avoiding hospital episodes related to AF treatment, but conventional cryoablation was not superior to the AVATAR protocol. This could have wide-ranging implications on how demand for AF symptom control is met. TRIAL REGISTRATION: Clinical Trials Registration: NCT02459574.

The long-term effect of thermal-guided second-generation cryoablation in paroxysmal and persistent atrial fibrillation.

BACKGROUND: Second-generation cryoballoon ablation is safe and effective in patients with paroxysmal (PAF) and persistent atrial fibrillation (AF). OBJECTIVE: This study aimed to assess the long-term clinical outcomes and freedom from AF in patients undergoing thermal-guided cryoablation without the use of an electrical mapping catheter. METHODS: All patients who had undergone thermal-guided second-generation cryoablation without electrical mapping between January 2015 and April 2018 at Eastbourne District General Hospital were retrospectively analysed. Success was defined as freedom from atrial arrhythmia lasting >30 s during the follow up period. RESULTS: The study included 234 patients with a mean age of 65.3 ± 10.6 years. There were 134 (57.0%) and 100 (42.7%) patients who had PAF and persistent AF respectively. Arrhythmia recurrence occurred in 38 of 134 (28.4%) PAF and 42 of 100 (42.0%) persistent AF patients after mean follow up of 40 ± 9.2 months. The patients with PAF had a significantly greater freedom from arrhythmia than patients with persistent AF (p = .040). The mean procedure time was 55.5 ± 12.2 min and the mean fluoroscopy time was 10.9 ± 4.8 min 73.5% of patients were discharged on the same day. CONCLUSION: Thermal-guided cryoablation is feasible, safe and results in freedom from arrhythmia in the majority of paroxysmal and persistent AF patients in the long term. Randomised controlled trials are required to confirm the findings of this study.

Long Term outcomes of percutaneous atrial fibrillation ablation in patients with continuous monitoring.

INTRODUCTION: There is limited data using continuous monitoring to assess outcomes of atrial fibrillation (AF) ablation. This study assessed long-term outcomes of AF ablation in patients with implantable cardiac devices. METHODS: 207 patients (mean age 68.1 ± 9.5, 50.3% men) undergoing ablation for symptomatic AF were followed up for a mean period of 924.5 ± 636.7 days. Techniques included The Pulmonary Vein Ablation Catheter (PVAC) (59.4%), cryoablation (17.4%), point by point (14.0%) and The Novel Irrigated Multipolar Radiofrequency Ablation Catheter (nMARQ) (9.2%). RESULTS: 130 (62.8%) patients had paroxysmal AF (PAF) and 77 (37.2%) persistent AF. First ablation and repeat ablation reduced AF burden significantly (relative risk 0.91, [95% CI 0.89 to 0.94]; P <0.0001 and 0.90, [95% CI, 0.86-0.94]; P <0.0001). Median AF burden in PAF patients reduced from 1.05% (interquartile range [IQR], 0.1%-8.70%) to 0.10% ([IQR], 0%-2.28%) at one year and this was maintained out to four-years. Persistent AF burden reduced from 99.9% ([IQR], 51.53%-100%) to 0.30% ([IQR], 0%-77.25%) at one year increasing to 87.3% ([IQR], 4.25%-100%) after four years. If a second ablation was required, point-by-point ablation achieved greater reduction in AF burden (relative risk, 0.77 [95% CI, 0.65-0.91]; P <0.01). CONCLUSION: Ablation reduces AF burden both acutely and in the long-term. If a second ablation was required the point-by-point technique achieved greater reductions in AF burden than "single-shot" technologies. Persistent AF burden increased to near pre ablation levels by year 4 suggesting a different mechanism from PAF patients where this increase did not occur.

A New Era in Epicardial Access for the Ablation of Ventricular Arrhythmias: The Epi-Co2 Registry.

OBJECTIVES: This multicenter registry aimed to assess the reproducibility and safety of intentional coronary vein exit and carbon dioxide insufflation to facilitate subxiphoid epicardial access in the setting of ventricular tachycardia ablation. BACKGROUND: Epicardial ablation for ventricular tachycardia is not a widespread technique due to the significant potential complications associated with subxiphoid puncture. The first experience in 12 patients showed that intentional coronary vein exit and carbon dioxide insufflation was technically feasible. METHODS: A branch of the coronary sinus was cannulated by means of a diagnostic JR4 coronary catheter. Intentional perforation at the distal portion of that branch was performed with a high tip load 0.014-inch angioplasty wire. A microcatheter was advanced over the wire into the pericardial space. Carbon dioxide was then insufflated into the pericardial space, allowing direct visualization of the anterior pericardial space to facilitate subxiphoid puncture. RESULTS: Intentional coronary vein exit was attempted in 102 consecutive patients in 16 different centers and successfully completed in 101 patients. Significant pericardial adhesions were confirmed in 3 patients, preventing carbon dioxide insufflation and epicardial ablation. None of the punctures were complicated with inadvertent right ventricular puncture or damage to a coronary artery. Significant bleeding (>80 ml) due to coronary vein exit occurred in 5 patients, without hemodynamic compromise. None of the patients required surgery. CONCLUSIONS: Coronary vein exit and carbon dioxide insufflation can be safely and reproducibly achieved to facilitate subxiphoid pericardial access in the setting of ventricular tachycardia ablation.

The effect of second-generation cryoablation without electrical mapping in persistent AF using continuous monitoring.

BACKGROUND: Second-generation cryoballoon ablation is safe and effective in patients with persistent atrial fibrillation (AF). The aim of this study is to report the real long-term AF burden and freedom from AF post-cryoablation using continuous monitoring, and to assess whether intraoperative confirmation of pulmonary vein isolation using electrical mapping is necessary. METHODS: A total of 33 patients (mean age 75.7 ± 5.6 years, 16 men) with persistent AF who underwent second-generation cryoablation without electrical mapping were reviewed. All patients had a cardiac implantable device and were followed up for a mean of 755 ± 170 days. RESULTS: AF burden significantly decreased from 67.51% ± 34.90% to 18.28% ± 26.65% at 1-year follow-up, and this reduction was maintained at final follow-up (18.26% ± 23.70%, p < 0.001). Continuous monitoring revealed a freedom from AF rate of 33% and 24% at 1-year and full follow-up, respectively. Patients who remained in persistent AF at final follow-up had a trend towards higher pre-ablation AF burden (81.6% ± 29.7% vs 57.3% ± 36.4%, p = 0.08). CONCLUSION: Second-generation cryoablation without confirming pulmonary vein isolation using electrical mapping is effective leading to significant reductions in AF burden based on continuous beat-to-beat monitoring at 1-year and long-term follow-up.

How many patients with heart failure are eligible for cardiac contractility modulation therapy?

BACKGROUND: Increasing evidence exists suggesting that cardiac contractility modulation therapy (CCM) improves symptoms in heart failure patients if various selection criteria are fulfilled. The aim of this study is to analyse an unselected sample of heart failure patients to establish what percentage of patients would meet the current criteria for CCM therapy. METHODS: All patients admitted to two district general hospitals in the UK in 2018 with a diagnosis of heart failure were audited for eligibility for CCM therapy. The selection criteria were (a) ejection fraction (EF) 25%-45%, (b) QRS duration less than 130 ms, (c) New York Heart Association (NYHA) class 3-4 and (d) treated for heart failure for at least 90 days and on stable medications. Exclusion criteria included: (a) significant valvular disease, (b) permanent or persistent atrial fibrillation, (c) biventricular pacing system implanted or QRS duration more than 130 ms and (4) patients not suitable for device therapy as a result of palliative treatment intent. RESULTS: A total of 475 patients were admitted with heart failure during the study period. From this group, 24 (5.1%) patients fulfilled the criteria for CCM therapy. The mean age and ejection fraction were 70.8 ± 10.2 and 32.5% ± 7.4%. The majority of patients were men (71%) and had an ischaemic cardiomyopathy (75%). If patients with atrial fibrillation were included, an additional 18 (3.8%) patients potentially may be eligible for CCM. CONCLUSION: Only 5.1% of all patients presenting with heart failure might benefit from cardiac CCM. This is a small proportion of the overall heart failure population. However, this population has no other current option for device therapy of their condition.

Utilising video technology in the cardiac catheter lab and operating theatre during the COVID-19 pandemic.

The COVID-19 pandemic has significantly altered working practices within hospitals. This includes surgical theatres and cardiac catheter laboratories. Here we describe how we have harnessed the use of video technology to improve the running of the cardiac catheter lab in our institution, reducing the exposure of staff members to COVID-19, reducing the need for personal protective equipment (PPE) and maintaining and enhancing educational and teaching opportunities for trainees.

An economic evaluation of an advanced video conferencing system for cardiac multidisciplinary team meetings.

INTRODUCTION: Current UK and international guidelines advocate the need for multidisciplinary team (MDT) discussion of selected patients undergoing either percutaneous or surgical cardiac procedures to decide the optimal treatment strategy. To date, it is unknown if using videoconference facilities is cost-effective. Therefore, we performed a cost analysis of using a high-speed internet video conferencing system compared with conventional face-to-face MDT meetings. METHODS: Costs of running a conventional MDT meeting vs a video conferencing MDT were modelled and compared over a 2-year period. Participants were also surveyed on the overall effectiveness of conducting remote MDTs. RESULTS: The set-up and maintenance cost of the video conferencing system over 2 years was £30 400. The staff costs of running the face-to-face MDT were £95 970 and the video conferencing MDT was £23 992.50. The total travel costs of the conventional face-to-face MDTs were £10 555.34. In total, the cost of the conventional face-to-face MDT was £106 525.34 and the video conferencing MDT was £54 392.50 representing a cost saving of 48.9%. Participants rated the effectiveness of conducing a remote MDT and the ease of technology use as very good. CONCLUSIONS: Video conferencing systems provide a highly cost-effective method of facilitating MDT meetings between cardiologists and cardiac surgeons at remote centres.

A trial of three non-invasive blood pressure monitors compared with invasive blood pressure assessment in atrial fibrillation and sinus rhythm.

OBJECTIVE: To investigate the accuracy of three non-invasive blood pressure (BP) devices in atrial fibrillation (AF) compared with invasive arterial BP. METHODS: One hundred patients aged 45-90 years, 63% male (50 in AF and 50 age matched controls in sinus rhythm [SR]) were identified with arterial lines measuring beat-to-beat BP fluctuation. Non-invasive BP measurements utilising the manual sphygmomanometer (MS), PulseCor R6.5 (PC) and automated sphygmomanometer (AS) were taken simultaneously with invasive BP in a randomised sequence. This was repeated three times in each patient. RESULTS: In SR differences in systolic BP (SBP) for MS, AS and PC were -0.34 mm Hg (95% CI -2.31 to 1.63; P = .733), -3.80 mm Hg (95% CI -5.73 to -1.87; P = .0001) and -3.90 mm Hg (95% CI -5.90 to -1.90; P = .0001) and for diastolic BP (DBP) were 6.02 mm Hg (95% CI 4.39-7.64; P < .0001), 8.95 mm Hg (95% CI 7.36-10.55; P < .0001) and 7.54 mm Hg (95% CI 5.89-9.18; P < .0001), respectively. In AF mean differences in SBP for MS, AS and PC were -7.33 mm Hg (95% CI -9.11 to -5.55; P < .0001), -5.29 mm Hg (95% CI -7.08 to -3.50; P < .0001) and -5.75 mm Hg (95% CI -7.54 to -3.96; P < .0001) respectively and for DBP were 5.28 mm Hg (95% CI 4.03-6.54; P < .0001), 6.26 mm Hg (95% CI 5.00-7.52; P < .0001) and 6.89 mm Hg (95% CI 5.64-8.15; P < .0001) respectively. CONCLUSIONS: The MS is accurate in SR because of direct assessment of Korotkoff sounds. Non-invasive BP assessment in AF is significantly less accurate. These findings have important prognostic and therapeutic implications.

The effect of atrial fibrillation intervention on nocturnal respiratory events in elderly patients with persistent AF.

BACKGROUND: Sleep-disordered breathing (SDB) and atrial fibrillation (AF) are associated. This study investigated the impact of AF intervention on 6-month home sleep testing data. METHODS: Sixty-seven patients (aged 66 to 86, 53% male) with persistent AF were randomized (1:1:1) to direct current cardioversion (DCCV) (22 patients), permanent pacemaker (PPM) + atrioventricular node ablation (AVNA) + DCCV (22 patients) or AF ablation (23 patients). Baseline and 6-month multichannel home sleep tests with the Watch-PAT200 (Itamar Medical Lts., Caesarea, Israel) were recorded. Implantable cardiac monitors (ICMs) (Medtronic Reveal XT, Minneapolis, Minnesota) in the DCCV and AF ablation groups, and PPM Holters in the 'pace and ablate' group were utilized to assess cardiac rhythm beat-to-beat throughout the study period. RESULTS: The prevalence of moderate-to-severe SDB [apnoea-hypopnoea index (AHI) ≥ 15/h] was 60%. At 6 months there was no change in AHI, Epworth sleepiness scale, sleep time, % REM sleep, respiratory desaturation index or central apnoeic events. Twenty-five patients (15 AF ablation, 9 DCCV and 1 following DCCV post-AVNA) maintained SR at 6 months confirmed on ICMs in these patients. AHI fell from 29.8 ± 26.6/h to 22.2 ± 20.4/h; P = 0.049. CONCLUSIONS: SDB is highly prevalent in patients with persistent AF. Restoration of sinus rhythm, and the associated long-term recovery of haemodynamics, is associated with a significant reduction in AHI. This implicates reversal of fluid shift from the lower limbs to the neck region, a key mechanism in the pathogenesis of SDB.

The development of AF over time in patients with permanent pacemakers: objective assessment with pacemaker diagnostics demonstrates distinct patterns of AF.

AIMS: To describe the long-term patterns of atrial fibrillation (AF) in patients with permanent pacemakers. METHODS AND RESULTS: A total of 2092 pacemaker Holter downloads were analysed in 323 patients with dual chamber permanent pacemakers, describing a cumulative 1031 patient-years of beat-to-beat monitoring. Four subtypes of AF were applied: (i) non-progressive low-burden PAF (NPLB-PAF, n = 120): such patients never have >1% AF burden throughout follow-up; (ii) chronic progressive PAF (CP-PAF, n = 55): AF burden increases but is never 100%; (iii) relapsing-remitting PAF (RR-PAF, n = 78): AF burden has reduced at least once by more than 2% and is never 100%; (iv) persistent AF (PersAF, n = 70): 100% AF burden for at least 28 days. Overall, mean AF burden rose 0.34% per year (P < 0.0001). After accounting for age, heart failure (HF) had a significant interaction with AF burden (P = 0.0022), but HATCH score and CVA/TIA did not. There were no differences in the frequency or duration of monitoring between the four AF subtypes. Atrial fibrillation episode frequency discriminated between subtypes (P = 0.0004). Eighteen of 70 (26%) patients with PersAF had pacemaker documented episodes of sinus rhythm (i.e. reversion to 'paroxysmal AF') after the onset of PersAF. CONCLUSION: In this cohort, the development of AF over time appears more complex than current definitions suggest. Atrial fibrillation can remain low burden without progression, remit-relapse, or progress as is described in currently accepted definitions. More frequent episodes of AF indicated a favourable subtype. Persistent AF is not inevitable, and can revert to paroxysmal AF. CLINICAL TRIAL REGISTRATION: NCT02016950, http://clinicaltrials.gov/show/NCT02016950.

Tissue doppler-derived contractile reserve is a simple and strong predictor of cardiopulmonary exercise performance across a range of cardiac diseases.

BACKGROUND: Resting echocardiographic measures of cardiac function such as left ventricular ejection fraction correlate poorly with exercise capacity. Assessment during exercise using measures less dependent on hemodynamic loading conditions, such as tissue Doppler imaging (TDI), may more accurately characterize the relationship between cardiac function and exercise capacity. METHODS AND RESULTS: One hundred one subjects with various cardiac diagnoses underwent exercise stress echocardiography with simultaneous cardiopulmonary gas exchange analysis. Standard two-dimensional, Doppler and spectral TDI parameters were assessed at both rest and peak exercise. Across all subjects the strongest relationship with peak oxygen uptake (pVO2 ) was with peak left ventricular systolic tissue velocity (S') during exercise (r = 0.84, P < 0.001). The strength of the relationship was greater than that observed with any other common echocardiographic measure of systolic or diastolic cardiac function. CONCLUSION: There is a very strong relationship between measurements of S' during exercise and exercise capacity. The previously observed poor correlation with standard measures of systolic and diastolic cardiac function may be explained both by the load dependence of parameters such as ejection fraction and by reliance on resting as opposed to exercise assessment.

The efficacy of intraoperative atrial radiofrequency ablation for atrial fibrillation during concomitant cardiac surgery-the Surgical Atrial Fibrillation Suppression (SAFS) Study.

INTRODUCTION: Studies assessing radiofrequency ablation (RFA) for atrial fibrillation (AF) performed at the time of concomitant cardiac surgery have reported high success rates. The efficacy of this treatment has primarily been determined by a single electrocardiogram (ECG) or 24-h Holter monitor at follow-up. We sought to assess the true efficacy of this procedure using prolonged cardiac rhythm monitoring. METHODS: One hundred patients with paroxysmal (n = 47) and persistent AF (n = 53) requiring cardiac surgery were enrolled. Patients were clinically reviewed 6 weeks post-operatively and were monitored with 7-day Holter with full disclosure, 6 months post-surgery. A cohort of 50 patients also underwent 7 day Holter monitoring preoperatively. AF recurrence was defined as >30 s of AF. RESULTS: At 6 months, 75% of patients were in sinus rhythm according to a single ECG. However, only 62% of patients were free from AF on 7-day Holter; all AF episodes in these patients were asymptomatic. The procedure resulted in a significant decrease in AF burden from 56.2% at baseline to 27.5% at 6 months follow-up, (p < 0.001). Predictors of AF recurrence were (1) pre-operative AF duration; (2) persistent compared with paroxysmal AF; (3) increasing left atrial diameter and (4) requirement for mitral valve surgery. CONCLUSIONS: Surgical RFA for the treatment of AF, during concomitant cardiac surgery, is a successful procedure and significantly reduces AF burden. However, 13% of patients have asymptomatic AF episodes only identified with continuous monitoring. This has important implications for post-operative anti-arrhythmic and anticoagulant management and for the definition of surgical AF ablation success.

The relationship between right ventricular pacing and atrial fibrillation burden and disease progression in patients with paroxysmal atrial fibrillation: the long-MinVPACE study.

AIMS: In patients requiring permanent pacemaker implantation for sinus node disease (SND) or atrioventricular (AV) block, right ventricular (RV) pacing has been demonstrated to increase the risk of developing atrial fibrillation (AF). The effects of RV pacing in patients with paroxysmal AF are less well defined. Short- and medium-term studies have suggested no significant correlation between RV pacing and atrial fibrillation burden (AFB) measurement; we sought to assess for an effect in the long-term. METHODS AND RESULTS: Sixty-six patients were randomized to receive either conventional dual chamber pacing (DDDR, n = 33), or dual chamber minimal ventricular pacing (MinVP, n = 33), for a period of at least 1 year. Patients were reviewed every 6 months and all pacemaker data were downloaded. The primary outcome measures were device-derived AFB and progression to persistent AF. The mean duration of study follow-up was 1.4 ± 0.6 years. Mean ventricular pacing was less in the MinVP cohort compared with the DDDR cohort (5.8 vs. 74.0%, P < 0.001). At follow-up, the device-derived AFB was significantly lower in the MinVP cohort when compared with the DDDR cohort (12.8 ± 15.3% vs. DDDR 47.6 ± 42.2%, P < 0.001). Kaplan-Meier estimates of time to onset of persistent AF showed significant reductions in the rates of persistent AF for MinVP pacing (9%) when compared with conventional DDDR pacing (42%), P = 0.004. CONCLUSION: Right ventricular pacing induces increased AFB in patients with paroxysmal AF in the long term. Dual chamber MinVP algorithms result in reduced AFB and reduced disease progression from paroxysmal to persistent AF in the long term.