Real-World Comparison of Classes IC and III Antiarrhythmic Drugs as an Initial Rhythm Control Strategy in Newly Diagnosed Atrial Fibrillation

The State of Use and Utility of Negative Controls in Pharmacoepidemiologic Studies

Uses of real-world data in drug safety and effectiveness studies are often challenged by various sources of bias. We undertook a systematic search of the published literature through September 2020 to evaluate the state of use and utility of negative controls to address bias in pharmacoepidemiologic studies. Two reviewers independently evaluated study eligibility and abstracted data. Our search identified 184 eligible studies for inclusion. Cohort studies (115, 63%) and administrative data (114, 62%) were, respectively, the most common study design and data type used. Most studies used negative control outcomes (91, 50%), and for most studies the target source of bias was unmeasured confounding (93, 51%). We identified 4 utility domains of negative controls: 1) bias detection (149, 81%), 2) bias correction (16, 9%), 3) P-value calibration (8, 4%), and 4) performance assessment of different methods used in drug safety studies (31, 17%). The most popular methodologies used were the 95% confidence interval and P-value calibration. In addition, we identified 2 reference sets with structured steps to check the causality assumption of the negative control. While negative controls are powerful tools in bias detection, we found many studies lacked checking the underlying assumptions. This article is part of a Special Collection on Pharmacoepidemiology.

Dronedarone Versus Sotalol in Antiarrhythmic Drug-Naive Veterans With Atrial Fibrillation

BACKGROUND

Sotalol and dronedarone are both used for maintenance of sinus rhythm for patients with atrial fibrillation. However, while sotalol requires initial monitoring for QT prolongation and proarrhythmia, dronedarone does not. These treatments can be used in comparable patients, but their safety and effectiveness have not been compared head to head. Therefore, we retrospectively evaluated the effectiveness and safety using data from a large health care system.

METHODS

Using Veterans Health Administration data, we identified 11 296 antiarrhythmic drug-naive patients with atrial fibrillation prescribed dronedarone or sotalol in 2012 or later. We excluded patients with prior conduction disease, pacemakers or implantable cardioverter-defibrillators, ventricular arrhythmia, cancer, renal failure, liver disease, or heart failure. We used natural language processing to identify and compare baseline left ventricular ejection fraction between treatment arms. We used 1:1 propensity score matching, based on patient demographics, comorbidities, and medications, and Cox regression to compare strategies. To evaluate residual confounding, we performed falsification analysis with nonplausible outcomes.

RESULTS

The matched cohort comprised 6212 patients (3106 dronedarone and 3106 sotalol; mean [±SD] age, 71±10 years; 2.5% female; mean [±SD] CHA2DS2-VASC, 2±1.3). The mean (±SD) left ventricular ejection fraction was 55±11 and 58±10 for dronedarone and sotalol users, correspondingly. Dronedarone, compared with sotalol, did not demonstrate a significant association with risk of cardiovascular hospitalization (hazard ratio, 1.03 [95% CI, 0.88-1.21]) or all-cause mortality (hazard ratio, 0.89 [95% CI, 0.68-1.16]). However, dronedarone was associated with significantly lower risk of ventricular proarrhythmic events (hazard ratio, 0.53 [95% CI, 0.38-0.74]) and symptomatic bradycardia (hazard ratio, 0.56 [95% CI, 0.37-0.87]). The primary findings were stable across sensitivity analyses. Falsification analyses were not significant.

CONCLUSIONS

Dronedarone, compared with sotalol, was associated with a lower risk of ventricular proarrhythmic events and conduction disorders while having no difference in risk of incident cardiovascular hospitalization and mortality. These observational data provide the basis for prospective efficacy and safety trials.

Long-term outcomes in patients treated with flecainide for atrial fibrillation with stable coronary artery disease

BACKGROUND

Class 1C antiarrhythmic drugs (AAD) have been associated with harm in patients treated for ventricular arrhythmias with a prior myocardial infarction. Consensus guidelines have advocated that these drugs not be used in patients with stable coronary artery disease (CAD). However, long-term data are lacking to know if unique risks exist when these drugs are used for atrial fibrillation (AF) in patients with CAD without a prior myocardial infarction.

METHODS

In 24,315 patients treated with the initiation of AADs, two populations were evaluated: (1) propensity-matched AF patients with CAD were created based upon AAD class (flecainide, n = 1,114, vs class-3 AAD, n = 1,114) and (2) AF patients who had undergone a percutaneous coronary intervention or coronary artery bypass graft (flecainide, n = 150, and class-3 AAD, n = 1,453). Outcomes at 3 years for mortality, heart failure (HF) hospitalization, ventricular tachycardia (VT), and MACE were compared between the groups.

RESULTS

At 3 years, mortality (9.1% vs 19.3%, P < .0001), HF hospitalization (12.5% vs 18.3%, P < .0001), MACE (22.9% vs 36.6%, P < .0001), and VT (5.8% vs 8.5%, P = .02) rates were significantly lower in the flecainide group for population 1. In population 2, adverse event rates were also lower, although not significantly, in the flecainide compared to the class-3 AAD group for mortality (20.9% vs 25.8%, P = .26), HF hospitalization (24.5% vs 26.1%, P = .73), VT (10.9% vs 14.7%, P = .28) and MACE (44.5% vs 49.5%, P = .32).

CONCLUSIONS

Flecainide in select patients with stable CAD for AF has a favorable safety profile compared to class-3 AADs. These data suggest the need for prospective trials of flecainide in AF patients with CAD to determine if the current guideline-recommended exclusion is warranted.

Absent or Mild Coronary Calcium Predicts Low-Risk Stress Test Results and Outcomes in Patients Considered for Flecainide Therapy

BACKGROUND

Flecainide is a useful antiarrhythmic for atrial fibrillation (AF). However, because of ventricular proarrhythmia risk, a history of myocardial infarction (MI) or coronary artery disease (CAD) is a flecainide exclusion, and stress testing is used to exclude ischemia. We assessed whether absent/mild coronary artery calcium (CAC) can supplement or avoid the need for stress testing.

METHODS

We assessed ischemic burden using regadenoson Rb-82 PET/CT in 1372 AF patients ≥50 years old without symptoms or signs of clinical CAD. CAC was determined qualitatively by low dose attenuation computed tomography (CT) (n = 816) or by quantitative CT (n = 556). Ischemic burden and clinical outcomes were compared by CAC burden.

RESULTS

Patients with CAC absent or mild (n = 766, 57.2%) were younger, more frequently female, and had higher BMI but lower rates of diabetes, hypertension, and dyslipidemia. Average ischemic burden was lower in CAC-absent/mild patients, and CAC-absent/mild patients showed greater coronary flow reserve, had fewer referrals for coronary angiography, and less often had obstructive CAD. Revascularization at 90 days was lower, and the rate of longer-term major adverse cardiovascular events was favorable.

CONCLUSIONS

An easily administered, inexpensive, low radiation CAC scan can identify a subset of flecainide candidates with a low ischemic burden on PET stress testing that rarely needs coronary angiography/intervention and has favorable outcomes. Absent or mild CAC-burden combined with other clinical information may avoid or complement routine stress testing. However, additional, ideally randomized and multicenter trials are indicated to confirm these findings before replacing stress testing with CAC screening in selecting patients for flecainide therapy in clinical practice.

Guideline-Concordant Antiarrhythmic Drug Use in the Get With The Guidelines-Atrial Fibrillation Registry

BACKGROUND

Antiarrhythmic drug (AAD) therapy for atrial fibrillation (AF) can be associated with both proarrhythmic and noncardiovascular toxicities. Practice guidelines recommend tailored AAD therapy for AF based on patient-specific characteristics, such as coronary artery disease and heart failure, to minimize adverse events. However, current prescription patterns for specific AADs and the degree to which these guidelines are followed in practice are unknown.

METHODS

Patients enrolled in the Get With The Guidelines-Atrial Fibrillation registry with a primary diagnosis of AF discharged on an AAD between January 2014 and November 2018 were included. We analyzed rates of prescription of each AAD in several subgroups including those without structural heart disease. We classified AAD use as guideline concordant or nonguideline concordant based on 6 criteria derived from the American Heart Association/American College of Cardiology/Heart Rhythm Society AF guidelines. Guideline concordance for amiodarone was not considered applicable, since its use is not specifically contraindicated in the guidelines for reasons such as structural heart disease or renal function. We analyzed guideline-concordant AAD use by specific patient and hospital characteristics, and regional and temporal trends.

RESULTS

Among 21 921 patients from 123 sites, the median age was 69 years, 46% female and 51% had paroxysmal AF. The most commonly prescribed AAD was amiodarone (38%). Sotalol (23.2%) and dofetilide (19.2%) were each more commonly prescribed than either flecainide (9.8%) or propafenone (4.8%). Overall guideline-concordant AAD prescription at discharge was 84%. Guideline-concordant AAD use by drug was as follows: dofetilide 93%, sotalol 66%, flecainide 68%, propafenone 48%, and dronedarone 80%. There was variability in rate of guideline-concordant AAD use by hospital and geographic region.

CONCLUSIONS

Amiodarone remains the most commonly prescribed AAD for AF followed by sotalol and dofetilide. Rates of guideline-concordant AAD use were high, and there was significant variability by specific drugs, hospitals, and regions, highlighting opportunities for additional quality improvement.

Therapie von Herzrhythmusstörungen mit Antiarrhythmika: kein Ende einer Ära

Antiarrhythmika sind eine Medikamentengruppe, die vor mehr als 100 Jahren eingeführt wurde. Jahrzehntelang wurden sie relativ breit und großzügig eingesetzt. Die Erkenntnis, dass proarrhythmische Effekte relativ häufig sind, und die Entwicklung neuer nicht medikamentöser Behandlungsalternativen (z. B. die Katheterablation bei Vorhofflimmern) haben dazu geführt, dass sich ihr klinischer Stellenwert in den letzten Jahren geändert hat. Schon seit Längerem wird das Ende der Antiarrhythmikaära prophezeit. In der Realität ergibt sich allerdings ein anderes Bild. Registerdaten zeigen, dass fast die Hälfte der Patienten mit Vorhofflimmern, die sich einer Katheterablation unterziehen, im weiteren Verlauf ein Antiarrhythmikum erhält. Eine unverändert wichtige Rolle spielen Antiarrhythmika (insbesondere Amiodaron) auch im Notfall und bei Patienten mit häufigen malignen ventrikulären Arrhythmien. Einen zunehmend relevanter werdenden Anwendungsbereich stellen angeborene Arrhythmien (langes-QT-Syndrom, Brugada-Syndrom, katecholaminerge polymorphe Kammertachykardien) dar. Antiarrhythmika gehören damit weiterhin zum Armamentarium des rhythmologisch orientierten Arztes. Es darf gehofft werden, dass neue Formen des EKG- und Patienten-Monitorings (z. B. Smartphone-EKGs) dazu betragen werden, die Überprüfung der Therapiewirksamkeit zu vereinfachen und die Therapiesicherheit zu optimieren.

Use of Flecainide for the Treatment of Atrial Fibrillation

Atrial fibrillation (AF) is the most common sustained arrhythmia and is associated with substantial morbidity and impairment of quality of life. Restoration and maintenance of normal sinus rhythm is a desirable goal for many patients with AF; however, this strategy is limited by the relatively small number of antiarrhythmic drugs (AADs) available for AF rhythm control. Although it is recommended in current medical guidelines as first-line therapy for patients without structural heart disease, the use of flecainide has been curtailed since the completion of the Cardiac Arrhythmia Suppression Trial. In clinical trials and real-world use, flecainide has proven to be more effective than other AADs for the acute termination of recent onset AF. Flecainide is also moderately effective and, with the exception of amiodarone, equivalent to other AADs for the chronic suppression of paroxysmal and persistent AF. In patients without structural heart disease, flecainide has been demonstrated to be safe and well tolerated relative to other AADs. Despite this favorable profile, flecainide is underutilized, likely due to a perceived risk of ventricular proarrhythmia, a concern that has not been borne out in patients without underlying structural heart disease. Guidelines for administration and use of flecainide are summarized in this review.