Rhythm Control and Its Relation to Symptoms during the First Two Years after Radiofrequency Ablation for Atrial Fibrillation

Reflections on the usefulness of today's atrial fibrillation ablation procedure endpoints and patient-reported outcomes

The improvement of Patient-reported outcomes, such as health-related quality of life, is the main indication for atrial fibrillation ablation. Despite this guideline derived indication for an AF ablation procedure the current standardized primary endpoint in AF ablation trials is still rhythm-related, and primarily a 30-second long AF episode. The review presents reflections on the non-rational arguments of using rhythm related endpoints rather than Patient-reported outcomes in AF ablation procedure trials despite the mismatch between many of the rhythm related variables and symptoms. Arguments for health-related quality of life as the most optimal primary endpoint in clinical trials are presented while atrial fibrillation burden is presented as the most optimal electrical complementary endpoint, apart from being the major variable in mechanistic trials.

A Review of the Wide Range of Indications and Uses of Implantable Loop Recorders: A Review of the Literature

Implantable loop recorders (ILR) are devices that are implanted subcutaneously on the chest, which enables the continuous monitoring of arrhythmias for up to three years. These devices have an important role in helping to make a diagnosis and supporting decisions about the best patient management. There are currently three companies that produce ILRs. The Reveal DX and XT device is produced by Medtronic. The Confirm device is produced by Abbott. The Biomonitor III device is produced by Biotronik. The established indications for ILR include the management of transient loss of consciousness and the diagnosis of undocumented palpitations; however, they are also used for less established applications, including atrial fibrillation (AF) monitoring and risk stratification in patients with previous myocardial infarction or inherited cardiomyopathies. There is also diverse literature exploring the use of these devices in other populations, including patients with conditions such as congenital heart disease, amyloidosis, stroke, obstructive sleep apnea, renal transplant and patients who undergo procedures such as AF ablation and coronary artery bypass graft. In this review, we describe how the use of ILR has been applied in different settings, including patients with cardiac and non-cardiac conditions as well as post-cardiac procedures. We then discuss the potential issues related to using ILR in these other indications.

Size matters in atrial fibrillation: the underestimated importance of reduction of contiguous electrical mass underlying the effectiveness of catheter ablation

Evidence has accumulated over the last century of the importance of a critical electrical mass in sustaining atrial fibrillation (AF). AF ablation certainly reduces electrically contiguous atrial mass, but this is not widely accepted to be an important part of its mechanism of action. In this article, we review data showing that atrial size is correlated in many settings with AF propensity. Larger mammals are more likely to exhibit AF. This is seen both in the natural world and in animal models, where it is much easier to create a goat model than a mouse model of AF, for example. This also extends to humans-athletes, taller people, and obese individuals all have large atria and are more likely to exhibit AF. Within an individual, risk factors such as hypertension, valvular disease and ischaemia can enlarge the atrium and increase the risk of AF. With respect to AF ablation, we explore how variations in ablation strategy and the relative effectiveness of these strategies may suggest that a reduction in electrical atrial mass is an important mechanism of action. We counter this with examples in which there is no doubt that mass reduction is less important than competing theories such as ganglionated plexus ablation. We conclude that, when considering future strategies for the ablative therapy of AF, it is important not to discount the possibility that contiguous electrical mass reduction is the most important mechanism despite the disappointing consequence being that enhancing success rates in AF ablation may involve greater tissue destruction.

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.

The Same is Not the Same: Device Effect during Bipolar Radiofrequency Ablation of Atrial Fibrillation

BACKGROUND

Different ablation devices deliver the same type of energy but use individual control mechanisms to estimate efficacy. We compared patient outcome after the application of radiofrequency ablation systems, using temperature- or resistance-control in paroxysmal and persistent atrial fibrillation (AF).

METHODS

This is an unselected all-comers study. Patients underwent standardized left atrial (paroxysmal atrial fibrillation, [PAF] n = 31) or biatrial ablation (persistent atrial fibrillation [persAF] n = 61) with bipolar RF from October 2010 to June 2013. Patients with left atrial dilatation (up to 57 mm), reduced left ventricular (LV) function, and elderly were included. We used resistance-controlled (RC) or temperature-controlled (TC) devices. We amputated atrial appendices and checked intraoperatively for completeness of pulmonary vein exit block. All patients received implantable loop recorders. Follow-up interval was every 6 months. Antiarrhythmic medical treatment endured up to month 6.

RESULTS

We reached 100% freedom from atrial fibrillation (FAF) in PAF. In perAF 19% of the RC but 82% of the TC patients reached FAF (12 months; p < 0.05). TC patients exhibited higher creatine kinase-muscle/brain (CK-MB) peak values. In persAF, CK-MB-levels correlated to FAF. No and no mortality (30 days) was evident. Twelve-month mortality did not correlate to AF type, AF duration, LV dimension, or function and age. Prolonged need of oral anticoagulants was 90.1% (RC) and 4.5% (TC).

CONCLUSION

In patients with persAF undergoing RF ablation, TC reached higher FAF than RC. Medical devices are not "the same" regarding effectiveness even if used according to manufacturer's instructions. Thus, putative application of "the same" energy is not always "the same" efficacy.

Patient-Reported Outcomes in Relation to Continuously Monitored Rhythm Before and During 2 Years After Atrial Fibrillation Ablation Using a Disease-Specific and a Generic Instrument

BACKGROUND

Atrial fibrillation (AF) ablation improves patient-reported outcomes, irrespective of mode of intermittent rhythm monitoring. We evaluated the use of an AF-specific and a generic patient-reported outcomes instrument during continuous rhythm monitoring 2 years after AF ablation.

METHODS AND RESULTS

Fifty-four patients completed the generic 36-Item Short-Form Health Survey and the AF-specific AF6 questionnaires before and 6, 12, and 24 months after AF ablation. All patients underwent continuous ECG monitoring via an implantable loop recorder. The generic patient-reported outcomes scores were compared with those of a Swedish age- and sex-matched population. After ablation, both summary scores reached normative levels at 24 months, while role-physical and vitality remained lower than norms. Responders to ablation (AF burden <0.5%) reached the norms in all individual 36-Item Short-Form Health Survey domains, while nonresponders (AF burden >0.5%) reached norms only in social functioning and mental component summary. All AF6 items and the sum score showed moderate to large improvement in both responders and nonresponders, although responders showed significantly greater improvement in all items except item 1 from before to 24 months after ablation. Higher AF burden was independently associated with poorer physical component summary and AF6 sum score.

CONCLUSIONS

The AF-specific AF6 questionnaire was more sensitive to changes related to AF burden than the generic 36-Item Short-Form Health Survey. Patients improved as documented by both instruments, but a higher AF burden after ablation was associated with poorer AF-specific patient-reported outcomes and poorer generic physical but not mental health. Our results support the use of an AF-specific instrument, alone or in combination with a generic instrument, to assess the effect of ablation.

CLINICAL TRIAL REGISTRATION

URL: https://www.clinicaltrials.gov. Unique identifier: NCT00697359.