Understanding Antiarrhythmic Drug Efficacy for the Clinical Practitioner: There Is More than Meets the Eye

Determining if a medication is effective should be easy: Either the condition is or is not improved. However, the truth is often more complex than that, including in the antiarrhythmic drug (AAD) management of atrial fibrillation. In clinical trials, AAD efficacy is usually determined by the time to first atrial fibrillation recurrence. Another AAD efficacy endpoint, in patients with cardiac implantable electrical devices, is a reduction of atrial fibrillation burden. Other cardiovascular outcomes have included hospitalization, heart failure, and cardiovascular or total mortality. In clinical practice AADs, for atrial fibrillation, are prescribed to reduce symptoms/improve quality of life, which usually correlate with reduced atrial fibrillation frequency, duration, and beneficial hemodynamic effects in certain patient subgroups. Time to first recurrence is not a reliable predictor of clinical efficacy endpoints in practice. This article presents a review for the practitioner of AAD efficacy endpoints in clinical trials versus those in clinical practice and why such differences are present.

Review of the 2020 ESC Guidelines for the Diagnosis and Management of Atrial Fibrillation-What Has Changed and How Does This Affect Daily Practice

The high prevalence of atrial fibrillation (AF) in the overall population and its association with substantial morbidity, increased mortality and health care cost has instigated significant basic and clinical research efforts over recent years. The publication of multiple new high-quality randomized multi-center trials in the area of AF management and the rapidly evolving technological progress in terms of diagnostic possibilities and catheter ablation in recent years demanded a revision of the previous ESC AF Guidelines from 2016. The 2020 guidelines provide up-to-date, evidence-based guidance for the management of AF. One of the most important innovations is the presentation of a new concept for structural characterization of AF (the “4S AF scheme”) replacing the traditional classification based on its temporal pattern alone (paroxysmal-persistent-permanent). The 4S-AF-scheme highlights the importance of systematic assessment of stroke risk, severity of symptoms, total AF burden and underlying substrate as the foundation for effective and individualized AF treatment for each and every patient. Further novelties relate to the presentation of an easy and intuitive management pathway (“ABC pathway”) and strengthening the recommendations for early rhythm control, in particular the role of first line catheter ablation in heart failure. Another core component of the guidelines is the focus on patient involvement to achieve optimal outcomes. Patient education, shared decision making and incorporation of patient values and patient reported outcome of treatment interventions as well as integrated care by a multidisciplinary team all have a central role in the proposed management pathway for AF.

The Current Landscape of Atrial Fibrillation and Atrial Flutter Clinical Trials: A Report of 348 Studies Registered With ClinicalTrials.gov

OBJECTIVES

This analysis sought to systematically characterize trial-level patterns in atrial fibrillation/atrial flutter (AF/AFL) by using the ClinicalTrials.gov database.

BACKGROUND

Despite an abundance of clinical trials in this field, there is a lack of high-level evidence guiding management of AF/AFL.

METHODS

We queried all closed, phase II to IV interventional trials registered in the ClinicalTrials.gov database through October 2016 that enrolled patients known to have AF/AFL. Published trials were evaluated for methodological quality, using the 3-item Jadad scale (range: 0 to 5, where 5 = highest quality).

RESULTS

The initial search yielded 465 uniquely registered studies, of which 348 directly studied AF/AFL. Of those studies, 173 (50%) were published, enrolling a median of 190 patients from a median of 15 sites. The volume of published trials increased over time (7% prior to 2008 vs. 41% from 2014 to 2016; p < 0.001 for trend). Of the completed trials, 29% remain unpublished. Industry sources accounted for most funding (54%). Recurrence of AF/AFL was the most common endpoint (45%), whereas rates of primary clinical endpoints were low (13%). The mean Jadad score of published trials of pharmacological approaches (n = 112) was 4.0 ± 1.4. Of the 61 AF/AFL trials involving ablation or device therapies, 69% were randomized, 28% were single-arm studies, and patient, proceduralist, and event-ascertainment blinding was used in 16%, 4%, and 44%, respectively.

CONCLUSIONS

Contemporary trials of AF/AFL are often multicenter and modest in size. The primary study endpoint is commonly recurrence of arrhythmia, even in high-quality and late-phase trials. Although methodological quality is high in trials of pharmacologic approaches, trials of AF/AFL ablation and device therapies variably employ randomization and blinding.

Differences in Quality of Life Between Atrial Fibrillation Patients with Low Stroke Risk Treated With and Without Catheter Ablation

BACKGROUND

Impacts of a single radiofrequency ablation (RFA) on quality of life (QoL) were not well investigated in atrial fibrillation (AF) patients with low stroke risk.

METHODS AND RESULTS

Nine hundred AF patients with low CHADS2 score (ie, CHADS2 ≤1) who completed both a baseline and 6-month Atrial Fibrillation Effect on QualiTy-of-life (AFEQT) questionnaire were selected from The Chinese Atrial Fibrillation Registry between 2011 and 2013. A final cohort of 222 patients was constructed after a propensity score matching with 74 in the RFA group and 148 in the non-RFA group. Domains of AFEQT were balanced at baseline between the 2 groups. No statistically significant differences were noted in QoL (all P>0.05) when AFEQT at 6 months was compared between groups, except for the symptoms domain (83.07±12.37 units in the RFA group vs. 77.68±17.14 units in the non-RFA group; P=0.008) and treatment satisfaction domain (76.34±14.92 units in the RFA group vs. 70.38±16.81 units in the non-RFA group; P=0.01). Within-group changes in all domains and the global score of the questionnaire were moderate to large, whereas between-group comparisons in baseline to 6-month changes and QoL at 6 months were small to moderate according to Cohen effect sizes.

CONCLUSIONS

QoL was balanced at baseline and improved at 6 months in both groups from this observational propensity-matched cohort based on the AFEQT questionnaire. However, RFA treatment was only associated with small-to-moderate superiorities over non-RFA treatment. The role of RFA in QoL improvement among AF patients with low stroke risk requires further research.

The HARMONY Trial: Combined Ranolazine and Dronedarone in the Management of Paroxysmal Atrial Fibrillation: Mechanistic and Therapeutic Synergism

BACKGROUND

Atrial fibrillation (AF) requires arrhythmogenic changes in atrial ion channels/receptors and usually altered atrial structure. AF is commonly treated with antiarrhythmic drugs; the most effective block many ion channels/receptors. Modest efficacy, intolerance, and safety concerns limit current antiarrhythmic drugs. We hypothesized that combining agents with multiple anti-AF mechanisms at reduced individual drug doses might produce synergistic efficacy plus better tolerance/safety.

METHODS AND RESULTS

HARMONY tested midrange ranolazine (750 mg BID) combined with 2 reduced dronedarone doses (150 mg BID and 225 mg BID; chosen to reduce dronedarone's negative inotropic effect-see text below) over 12 weeks in 134 patients with paroxysmal AF and implanted pacemakers where AF burden (AFB) could be continuously assessed. Patients were randomized double-blind to placebo, ranolazine alone (750 mg BID), dronedarone alone (225 mg BID), or one of the combinations. Neither placebo nor either drugs alone significantly reduced AFB. Conversely, ranolazine 750 mg BID/dronedarone 225 mg BID reduced AFB by 59% versus placebo (P=0.008), whereas ranolazine 750 mg BID/dronedarone 150 mg BID reduced AFB by 43% (P=0.072). Both combinations were well tolerated.

CONCLUSIONS

HARMONY showed synergistic AFB reduction by moderate dose ranolazine plus reduced dose dronedarone, with good tolerance/safety, in the population enrolled.

CLINICAL TRIAL REGISTRATION

ClinicalTrials.gov; Unique identifier: NCT01522651.

A placebo-controlled, double-blind, randomized, multicenter study to assess the effects of dronedarone 400 mg twice daily for 12 weeks on atrial fibrillation burden in subjects with permanent pacemakers

Purpose

Dronedarone is a benzofuran derivative with a pharmacological profile similar to amiodarone but has a more rapid onset of action and a much shorter half-life (13–19 h). Our goal was to evaluate the efficacy of dronedarone in atrial fibrillation (AF) patients using dual-chamber pacemakers capable of quantifying atrial fibrillation burden.

Methods

Pacemakers were adjusted to optimize AF detection. Patients with AF burden >1 % were randomized to dronedarone 400 mg twice daily (BID) or placebo. Pacemakers were interrogated after 4 and 12 weeks of treatment. The primary endpoint was the change in AF burden from baseline over the 12-week treatment period. Patients with permanent AF, severe/recently decompensated heart failure, and current use of antiarrhythmic drugs were excluded. AF burden was assessed by a core laboratory blinded to treatment assignment.

Results

From 285 patients screened, 112 were randomized (mean age 76 years, 60 % male, 84 % hypertensive, 65 % with sick sinus syndrome, 26 % with diabetes mellitus type II, 15 % with heart failure). Baseline mean (SEM) AF burden was 8.77 % (0.16) for placebo and 10.14 % (0.17) for dronedarone. Over the 12-week study period, AF burden compared to baseline decreased by 54.4 % (0.22) (P = 0.0009) with dronedarone and trended higher by 12.8 % (0.16) (P = 0.450) with placebo. The absolute change in burden was decreased by 5.5 % in the dronedarone group and increased by 1.1 % in the placebo group. Heart rate during AF was reduced to approximately 4 beats/min with dronedarone (P = 0.285). Adverse events were higher with dronedarone compared to placebo (65 vs 56 %).

Conclusions

Dronedarone reduced pacemaker-assessed the relative AF burden compared to baseline and placebo by over 50 % during the 12-week observation period.

Presence and severity of obstructive sleep apnea and remote outcomes of atrial fibrillation ablations - a long-term prospective, cross-sectional cohort study

BACKGROUND

Prior studies suggested that obstructive sleep apnea (OSA) promotes recurrence of arrhythmia in patients after atrial fibrillation (AF) ablation.

METHODS

In this prospective, long-term, observational study, we enrolled 290 consecutive patients admitted for AF ablation. Prior to the ablation, all patients underwent a polygraphy sleep study for the diagnosis of OSA. After the procedure, patients were followed up for mean time of 30 months for AF reoccurrence. OSA was diagnosed when apnea-hypopnea index (AHI) was ≥5. Patients were subsequently divided into groups according to the OSA severity: mild OSA (AHI 5-15/h), moderate OSA (AHI >15 and ≤30/h), and severe (AHI >30/h).

RESULTS

After excluding patients disqualified from the procedure, and those with central sleep apnea, the study population consisted of 251 patients, mean age 57.6 years [163 (64.9%) male]. OSA was present in 115 (45.8%) patients, while in 137 (54.6%) cases, we observed reoccurrence of AF. Recurrence was more often in patients with, than without, OSA (65.2 vs. 45.6%; p = 0.003). We also observed that along with rising OSA severity rose also the number of patients in whom AF was detected during the follow-up period (45.6 vs. 66.2 vs. 57.6 vs. 81.8%; p = 0.005; for non-OSA, mild, moderate, and severe, respectively).

CONCLUSIONS

OSA is highly prevalent in AF patients. The presence of OSA lowers chances on successful AF ablation. Early screening, and treatment for OSA in AF patients, may improve low success rates of AF ablation procedures.

Understanding efficacy end-points in studies of field-directed therapy for actinic keratosis

BACKGROUND

The rates of short-term clearance of actinic keratoses appear to be comparable in clinical trials of topical treatments used in field therapy, but direct comparisons of efficacy results can be problematic. Trials use different efficacy end points, have different study designs, involve different anatomic sites, and enroll different patient populations. In addition, because adherence in real-world clinical practice differs from that observed in clinical trials, conclusions drawn from efficacy outcomes can be misleading. The objective of this review was to examine the efficacy end points used in studies of topical therapy for actinic keratosis, address other factors influencing efficacy outcomes in these studies, and discuss the possible influence of nonadherence on effectiveness.

METHODS

Review of the available literature on topical therapy for actinic keratosis.

RESULTS

The end points used to determine efficacy of therapies for actinic keratosis include a disparate group of outcomes, which can often make comparison between studies impossible.

CONCLUSIONS

Efficacy end points of clinical studies designed to assess the treatment of actinic keratosis should be standardized to facilitate between-trial comparisons, and studies should focus on the end points that are most clinically relevant.

Cross-trial comparisons: a source of confusion, use, or both in the management of patients with atrial fibrillation?

Many medical therapies are shaped by clinical trial data. However, individual clinical trial results sometimes appear discordant for the same tested treatments, and competing treatment strategies are often not directly tested. Clinicians are forced to make decisions by extrapolating information from different trials of similar but nonidentical therapies. In an era where increasing medical complexity demands sound evidence-based decisions, clinicians must navigate through these issues to arrive at optimal patient-specific management decisions. Using trials investigating therapies for atrial fibrillation, we attempt to highlight the important points for practitioners to consider when making these comparative intertrial judgments.

[Atrial fibrillation in 2010: an increasing morbidity and mortality burden]

AF, a frequent and banal arrhythmia, is a debilitating and costly disease. The majority of patients with AF are aged 60 to 80 years, but the prevalence is as high as 10% after 80 years and the incidence increases in recent years in an "epidemic" way. AF is responsible for an excess of mortality with an relative risk between 2 and 4 depending of age and sex, especially as cardiovascular risk factors are associated. The morbidity is also important, with cerebral systemic embolism (2-3% per year), heart failure (1 patient for 3), and a total risk of hospitalization from 20 to 30% per year for AF patients with high cardiovascular risks. Whatever be the reasons for hospitalization, cardiovascular or not, in connection with AF or not, these reasons must be well analyzed, so that the risk of occurrence of hospitalization should reflect the efficacy of anti-arrhythmic drugs, or of their complications, or of the comorbidities associated with AF, so common in these older subjects. This morbidity-mortality composite endpoint should now be used in AF randomized trials, as occurring more frequently than mortality (4% per year) or embolic or hemorrhagic usual endpoints. Medico-economic consequences are significant and AF cost is almost 1% of total health spending, with 20% to 30% of the cost for anti-arrhythmic or anti-thrombotic drugs, and 50 to 60% for hospitalizations. Prevention of hospitalizations related to atrial fibrillation may represent a therapeutic target priority on the medico-economic ground.

Designing comparative effectiveness trials of surgical ablation for atrial fibrillation: experience of the Cardiothoracic Surgical Trials Network

OBJECTIVE

Since the introduction of the cut-and-sew Cox maze procedure for atrial fibrillation, there has been substantial innovation in techniques for ablation. Use of alternative energy sources for ablation simplified the procedure and has resulted in dramatic increase in the number of patients with atrial fibrillation treated by surgical ablation. Despite its increasingly widespread adoption, there is lack of rigorous clinical evidence to establish this procedure as an effective clinical therapy.

METHODS

This article describes a comparative effectiveness randomized trial, supported by the Cardiothoracic Surgical Clinical Trials Network, of surgical ablation with left atrial appendage closure versus left atrial appendage closure alone in patients with persistent and long-standing persistent atrial fibrillation undergoing mitral valve surgery. Nested within this trial is a further randomized comparison of 2 different lesions sets: pulmonary vein isolation and the full maze lesion set.

RESULTS

This article addresses trial design challenges, including how best to characterize the target population, operationalize freedom from atrial fibrillation as a primary end point, account for the impact of antiarrhythmic drugs, and measure and analyze secondary end points, such as postoperative atrial fibrillation load.

CONCLUSIONS

This article concludes by discussing how insights that emerge from this trial may affect surgical practice and guide future research in this area.